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I. Non-Resume Type Cruise Control - 73

1. Road Test Step 1 Step 2 Step 3 Step 4 Step 5 Step 6 Step 7 Put dash switch in OFF position Drive car to 50 mph Push engagement switch button on turn signal lever and release System should remain inoperative Put dash switch in CRUISE center position on 1977 79 models Amber light should come on On 1980 and later models put dash switch in ON AUTO position and Amber light should come on Engage system by momentarily pushing the turn signal engagement switch button and releasing at 50 mph remove foot from ac celerator Green light should come on when button is released and system is engaged Vehicle should maintain speed of 50 mph Note amount if any by which car speed dif fers from the 50 mph speed when engaged This is called lock in error and can cor rected by the adjustment procedure Put dash switch in AUTO position on a 1977 thru 1979 model The vehicle speed should not change Push engagement switch button in to the de tent position and hold on a 1977 thru 1980 model or push slide switch and hold on a 1981 or later model Vehicle should acceler ate at a controlled rate Release slide or but ton to engage system at cruise speed or ap proximately 55 mph System should now be set at a new speed and vehicle should main tain that speed Depress brake pedal an estimated 1 2 inch green light should go out confirming action of electric brake release switch an
2. 71 424 21 9 e1n514 CRUISE CONTROL CRUISE CONTROL I P SWITCH ENGAGEMENT SWITCH SPEED ORN ECM SENSOR CRUISE ENGAGE REEN IND VISE ON mann IND 961 2 SPEED SENSOR 919 8 BRAKE K WHT 1 243 J DRIVE iz Bag 0 8 BLK W BUFFER HEADLAMP AMPLIFIER SWITCH TI EX ED CRUISE CONTROL l d CONNECTOR SWITCH T 0 5 BLU LGT BLK ES P2 N C T 0 5 GRN DRK CRUISE q er BODY TTE THE CRUISE CONTROL E FUSE FUSE gt VACUUM VALVE 3 20 2 Q TO AD TO 1 101 CRUISE VALVE DR a 2 IGNITION V SWITCH IGNITION 4 4 hdi ap Bg SWITCH CLOSED SWITCH IGNITION IN FUSE ENGINE an DRIVE 10 AMP GROUND GE MINI FUSE PANEL CRUISE CONTROL Pel POWER VALVE k m ECM JINODUJID JOJUODJ BSINJD SU 10 ayi SI 21 9 aINbIy 9515 jang 3 G sisouDei 2 21u04129 3 VI Electronic Cruise Control Code 60 Cruise Control Circuit Transmission Not In Drive Code 60 figure 6 13 indicates that the transmission was not in drive when the Cruise Control was engaged Whenever the condition which set Code 60 is present the Cruise Control will disengage To begin the diagnosis perfo
3. check for pinched or disconnected vacuum hoses and loose or binding throttle linkage see figure 1 21a 1 21b Check the servo rod figure 1 23a bead chain figure 1 23b or Bowden wire combination Bowden cable bead chain figure 1 23c for excess slack This con nection should have a minimum slack but not be so tight as to affect hot curb idle BOWDEN WIRE Figure 23c Bowden Wire Combination Bowden Cable Bead Chain 42 lar AL a tat LENGTE _ 7 24 LLLA O is ees amp fter YO f vor A PIRE btn nn Gid r yad a 4 yo 7 e an ce 1 Non Resume Type Cruise Control epp 27 Kotd Gem en ee Non Resume Type Cruise Control jaf 2 Step 3 Make sure the vehicle is equipped with the correct transducer and servo check out the part number figure 1 24 gem ama uma anana Step 4 If surging remains the most probable cause is a restricted vacuum hose or fit 0 ting to PORT on the TRANSDUCER IMOMENTARY MOMENTARY CRUISE CONTROL I Step 5 If no defect is found replace the trans ENGAGEMENT SWITCH OFF ON ducer and road test the vehicle SHOWN IN AT REST POSITION EU 0 N i DARK BLUE D CRUISE LAMP Fo RESISTANCE WIRE PNE ds 40n ENGAGE TERMINAL LIGHT IGNITION BRAKE RELEASE TERMINAL E SWITCH
4. lated to the proper operation of the aspirator system ASPIRATOR For example a plugged hose at POINT C figure 3 3 can cause the cruise system to become inoperative a plugged hose at POINT A causes cruise problems only when the engine is under heavy load The following steps describe aspirator system diagnostics and service Step 1 Insure that all hoses and connections are se curely in place Make sure the check valve position arrow shaped is correct uM J VACU 30 a Step 2 Connect a vacuum gauge to the AS PIRATOR output POINT A figure 3 2 Then start and run the engine at 2500 RPM in a closed loop operation Check with a dwell meter The vacuum gauge should read Figure 3 2 Connect a Vacuum Gauge to the at least 5 inches Hg If eua u is lower Aspirator Output remove and clean the aspirator with mineral spirits and re check Step 3 Check the AIR PUMP for output If there is no output service the air pump If no defect is found proceed to Step 4 Step4 Disconnect the vacuum gauge at POINT A gt Plug the 72 CHECK VALVE at POINT B Then blow air into the RESUME VALVE HOSE at POINT C Do not use compressed air A proper free flow condition is indicated if air exits at POINT A Step 5 Remove the plug from the ENGINE MAN IFOLD VACUUM HOSE at the manifold side of the 72 CHECK VALVE POINT B Plug the hose at POINT A Blow air into the RESUME VALVE HOSE POINT C
5. Air should exit at POINT B This completes a sys tem check in one direction Proceed to Step 6 Step 6 Check system air flow in the opposite direc tion Plug POINT B and blow air in at POINT A Then plug POINT A and blow air in at POINT B In either condition air should not exit at POINT C 3 2 e Ill Aspirator Assisted Vacuum System NOTES 3 3 Ill Aspirator Assisted Vacuum System AIR PUMP PIPE HOSE ASPIRATOR C ASPIRAT n AIR MANAGEMENT 2 PORT VARYE ATMOSPHERE CHECK VALVE A A TO MANIFOLD a gt VACUUM 3 PORT CHECK VALVE HOSE TO CRUISE TRANSDUCER RESUME VALVE Figure 3 3 Aspirator Assisted Vacuum System Schematic 4 car W END SET 3 4 Aspirator Assisted Vacuum System Ill Aspirator Assisted Vacuum System NOTES 3 5 3 6 IV Vacuum Assisted Systems General Operation and Applications Thg 1981 ick LeSabre Buick Electra and Oldsmobile 88 and 98 with a 4 1 liter V6 engine 4 speed transmission and liter engine with 4 speed transmission require vacuum assist for heavy load cruise operation Refer to figure 4 1 During the normal vacuum conditions of light to moderate load air flows from PORT A to PORT to the INTAKE MANIFOLD The single arrows in figure 4 1 show this air flow A small amount of air also flows from PORT A to PORT through the C
6. Electrical and Vacuum Operation Electrical Operation Vacuum Operation System Diagnostics and Service 1 Cruise System Inoperative 2 Cruises Over Under Set Speed 3 Surging Electrical System Schematic Vacuum System Schematic Combined Electrical Vacuum System SCOhemati0 data ea ak ai Resume Type Cruise Control General Operation Cruise System Components System Diagnostics and Service 1 Cruise System Inoperative 2 Cruises Over Under Set Speed 3 Surging Electro pneumatic System 5 VI Page Aspirator Assisted Vacuum System Horno u E 3 1 General Operation 3 1 System Diagnostics 3 2 Vacuum System Schematic 3 4 Vacuum Assisted Systems 4 1 General Operation and Applications 4 1 System Diagnostics 4 2 Diesel Transducer Non Resume and Resume Systems 5 1 Identification 5 1 System Diagnostics 5 1 Electronic Cruise Control 6 1 Non D F l and Computer Integrated DEL Cadillab 60400449264 decent vedas eed ns 6 1 General Description 6 1 Co
7. 2 terminal black wire Step 2 above Also two peaks should occur within six feet of car travel This check requires a high quality voltmeter 20 000 ohms per volt or greater Vacuum System Inspection Engine Operational Step 1 Prior to starting the engine disconnect the bead chain cable or actuating rod at the servo unit Step2 Disconnect the electrical connectors at the vacuum control and servo unit solenoid valves Step 3 Actuate both the vacuum control and servo unit solenoid valve with jumper wires This is done by connecting jumper wires from the battery positive terminal to one terminal on each valve and grounding the remaining terminal on each valve with another set of jumper wires Step 4 Step 5 Start the engine and let idle With brake pedal in free position diaphragm should pull in to full stroke Have a helper depress the brake pedal down about 172 inches and the diaphragm should relax to its free position proving that the vacuum release valve is working and its hose unobstructed Step 6 If system will not hold vacuum remove brake release vent valve hose at servo unit and plug servo unit hole manifold vacuum should be open Step 7 Ifservounit draws down then problem condi tion exists in brake release vacuum vent system Step 8 If servo unit will draw down inspect dia phragm and connectors at valves for leaks 6 17 gt 04405
8. BRAKE PEDAL A Pa 4 DEPRESSED L 5 YEL 904 L6 C103 5 PNK BLK 919 j PONE ET 5 YEL 904 C290 904 B 5 YEL BLK i 5 PNK BLK e CRUISE CONTROL SWITCH I o AUTO CRUISE PANEL CRUISE 5 YEL LIGHT ENGAGE BLK CRUISE ON SEE INSTRUMENT INDICATOR 5 PNK BLK INDICATOR PANEL LIGHTS GREEN AMBER Z C223 ENGAGE SWITCH ASSEMBLY RESUME ACCEL SET COAST CRUISE CONTROL ENGAGE SWITCH ASSEMBLY HARNESS CONNECTOR VIEW CRUISE A INDICATOR 8 RESUME ACCEL E POWER cits CRUISE SOLENOID ET INPUT CONTROLLER GROUND INPUT von POWER GROUND ENABLE OUTPUT servoouteut 6 C C226 DIESEL DIGITAL DIESEL MECHANICAL 2 C226 PERATED SPEEDOMETER SPEEDOMETER 5 DK BLU 403 5LTBLU 402 BY BRAKE 5 151 td ae C290 0 we 5230 x COMPUTER 5 WHT 994 FROMS32 278 POWER 5 OK BLU WHT 403 35 LT GRN 402 VACUUM NTROL V6 t Q RELEASE 9 Ob 101 l VALVE LT GRN M 995 PAGES 52 65 EX lt LIVE VALVE 5BLK 151 SENSORS BLK 931 Y w 5 BLU WHT 403 SLTBLU 402 CRUISE SERVO F pire ll WITH BRAKE RED 962 A TOS CRUISE PEDAL VACUUM DEPRESSED 5 BLK B 151 TTI BUFFER SOLENOID AMPLI
9. Electronic Cruise Control RESUME ACCEL SPEED SENSE INPUT C714 5 TAN 961 Je c CRUISE CONTROL ENGAGE SWITCH ASSEMBLY HARNESS CONNECTOR VIEW ASSEMBLY ELECTRONIC FUEL INJECTION DRIVE ADL SWITCH C223 8 BLK 243 WHT ELECTRONIC 714 CONTROL MODULE C J SET COAST INPUT DRIVE e vory RETURNS 20 5 1 B C716 w C715 LT GRN 431 PNK M 476 BUFFER BLK AMP LIFIER DFI ENGINE DATA 5 476 SENSORS BLK i 5 BLK PNK 476 5618 x 5 BLK PNK 996 Typical Circuit Operation D F l Refer to the D F I cruise schematic diagram on the fold out page figure 6 11 With the IGNITION SWITCH in Run voltage is applied through the C C FUSE to the CRUISE CON TROL SWITCH and the CRUISE CONTROL RELEASE SWITCH With the control switch in On Auto cur rent flows through the amber indicator bulb to ground Current also flows through terminal D on the control switch and follows 2 paths 1 to the ELEC TRONIC CONTROL MODULE as the Cruise Control Enable signal and 2 to the ENGAGE SWITCH ASSEMBLY Current flow from the CRUISE CONTROL RELEASE SWITCH follows 2 paths 1 to the ECM as the Brake Input signal and 2 to the VACUUM CONTROL VALVE SOLENOID The VEHICLE SPEED SENSOR sends low voltage sig nal pulses which represents car speed to the BUFFER AMPLIFIER The Amplifier modifies the pulses to put them in the right form for t
10. Must be less than 1 0 volt D C Momentarily increase idle speed for several seconds Voltmeter must indicate less than 1 0 volt D C Any indications above 1 0 volt D C replace controller Step 3 Step 4 e Instrument Panel Switch Amber Lamp Inoperative or Maifunctioning Engine Off Step 1 Turn ignition switch ON Step 2 Place instrument panel switch in AUTO or CRUISE v VI Electronic Cruise Control Step3 If amber ON lamp is not illuminated check for burned out lamp open ground wire open connector inoperative switch blown fuse or printed circuit Step 4 Place instrument panel switch in OFF position Step 5 If amber ON lamp is illuminated check for shorted leads or inoperative switch or blown fuse f Instrument Panel Switch Green Cruise Lamp Circuit Step 1 If road test shows system controls speed and green indicator light is inoperative check for burned out lamp or open in wiring be tween switch connector and controller con nector pink wire and inoperative controller With I P switch in ON AUTO ignition on ground cavity in controller connector green lamp should light If it does but not during road test replace controller Step2 If green indicator remains when system is not controlling speed check for short in harness between switch and controller con nector pink wire If OK replace controller or ECM A
11. On V 6 equipped cars with the speed sensor circuit is similar to DFI except the speed signal is sent to an electronic controller or control module for cruise control purposes figure 6 3 On diesel equipped cars with digital speedometer clusters the cruise control circuit is the same as used on V 6 however diesel equipped cars with mechanical speedometer clusters do not use a buffer amplifier in their speed sensor circuit Vacuum Control Valve The vacuum control valve figure 6 4 opens when the system is engaged and the green light on the instru ment panel switch is illuminated The valve operates in response to a signal from the ECM or the electronic controller When the vacuum control valve is open vacuum is available at the servo unit solenoid valve for control of the servo unit as described below The vac uum control valve is closed when the system is off Servo Unit Solenoid Valve The solenoid valve constantly modulates vacuum to the servo unit in response to commands from the electronic controller or ECM so that the throttle is in the proper position for the desired cruise speed fig ure 6 4 Servo Unit The Servo Unit figure 6 4 is a vacuum actuated vari able position diaphragm assembly that positions the throttle when the system is in operation It operates the throttle linkage via a bead chain actuator 4 1 liter V 6 car combination chain and cable actuator 4 1 liter V 8 car or rod actua
12. RELEASE VALVE J C ya a us THROTTLE Figure 1 26 AC Cruisemaster System Non resume Type Vacuum System Schematic 1 18 7919 Non Resume Type Cruise Control IGNITION SWITCH FUSE 12 VOLT BATTERY BEAD CHAIN 92 9 9 9 9 2 9 9 2 9 9 THROTTLE Figure 1 27 Combined Electrical Vacuum System Schematic MOMENTARY MOMENTARY CRUISE CONTROL ENGAGEMENT SWITCH OFF ON SHOWN IN AT REST POSITION BRAKE RELEASE I Non Resume Type Cruise Control ua um um G G un r I I I 1 L I f i li I I I I I R CRUISE LAMP RESISTANCE WIRE A 2 a 40 n 6 LIGHT TERMINAL q ENGAGE TERMINAL Idi 772 v1 ROTATION WITH E SPEED INCREASE 2 i s HOLD TERMINAL SWITCH i b f 4 po pou 27 VARIABLE Y li PORT C CLUTCH ORIFICE 2 lt pe T NS i SPEED i I SWITCH i IFILTERED AIR 0 VACUUM RELEASE VALVE i PORT A VACUUM SHUT OFF VALVE 1 CRUISE 4 4 LAMP 1 CIRCUIT w 1 SOLENOID 55 1 ENERGIZED SERVO X AIR FILTER 1 f a ats Fs a um G mm
13. cruise control switch and transducer are similar to the components discussed in of this service manual Figure 2 2 is a resume type cruise control transducer Unlike the non resume transducer it features a re sume solenoid valve and a special clutch arrangement Figure 2 1 Resume Cruise Control Lever ON OFE tA Bel Leck SPEEDOMETER CABLE DRIVE CABLE ENGAGE VACUUM SOURCE RESUME SOLENOID VALVE PP P Figure 2 2 Resume Cruise Control Transducer 2 1 pn s s Resume Type Cruise Control Open the fold out page 2 6 figure 2 9 Cruisemaster System with Resume Electro Pneumatic Schematic The electro pneumatic operation of the resume type system figure 2 9 can be compared to the non resume system for similarity figure 1 27 However the resume system components operate differently e When the brake pedal is depressed the clutch solenoid within the transducer remains energized The resume solenoid coil is not energized which shuts off vacuum to the transducer e The transducer features a resume spindle assembly which allows it to retain a mechanical memory of the vehicle speed when the brake pedal was depressed figure 2 3a When the slider switch is moved to the resume
14. electrically good and the resistance re mains high replace the transducer Also check the 40 Ohm resistance wire from point D to point E If the electrical circuits have no defects check the vacuum system First place the transmission in Park set the hand brake and start the engine Step 9 Step 10 Check for vacuum at PORT B fold out figure 1 26 Repair as necessary After required repairs or adjustments re connect all electrical connectors and vac uum hoses Then road test the vehicle If the system remains inoperative replace the transducer B Cruises Over Under Set Speed Step 1 Perform a general inspection of the cruise control system Check for pinched or dis connected vacuum hoses and a loose or binding or tight throttle linkage figure 1 21a and b If the vehicle cruises consis tently under the set speed first look for a vacuum leak 2 Adjusting the Orifice Tube Changes Cruise Speed If defect is found during Step 1 adjust the orifice tube figure 1 22 If the vehicle cruises below the set speed screw the orifice tube outward If the vehicle cruises above the set speed screw the orifice tube inward Each inch turn of the orifice tube changes cruise speed about 1 mph After adjustment make sure the lock nut is snug Road test and check cruise control tion at 50 mph Perform a general inspection of the cruise control system
15. figure 1 7 The servo unit is connected to the carburetor by a rod or linkage a bead chain or a Bowden cable or combination Bowden cable bead chain linkage The servo unit maintains desired vehicle speed by receiving a controlled amount of vacuum from the transducer This vacuum adjusts the tension on the rod bead chain or other connection to the car buretor which controls throttle sek Are cones hakanan ALAA arel 24 0706 i A 4 Combination Cruise Release Electric Switch and Vacuum Release Valve figure 1 8 Whenever the brake pedal is depressed the electric cruise release switch disengages the system As an additional feature the vacuum release valve also disengages the system when the brake pedal is pressed Both of these controls are mounted on the brake pedal bracket l Non Resume Type Cruise Control x SPEEDOMETER CABLE ENGAGE PORT A Figure 1 6 AC Cruisemaster non resume type Transducer Figure 1 7 Servo unit VACUUM RELEASE VALVE BRAKE PEDAL BRACKET gn SWITCH Figure 1 8 Brake Activated Electric and Vacuum Cruise Release Controls I Non Resume Type Cruise Control VACUUM CONNECTOR ELECTRICAL CONNECTION Figure 1 9 Valve and Switch Assembly on 1981 and Later Models Equipped with Lock up Torque Converter Transmission 5 Combination Vacuum Release Valve and Trans mission Lock up Torque Converter Clut
16. from bottom to top A thru H on switch assembly Step3 checks should indicate this following Instrument Panel Switch Off Car Test 1977 to 1979 Instrument Indication Panel Between Terminals Switch Position open o Instrument Panel Switch a On Car Check Switch Engine Off 1980 and Later Step 1 Turn ignition ON Step2 Connect test light or voltmeter to ground Step 3 Disconnect the 3 wire connector from the turn signal lever engage switch harness to the cruise harness connector Step4 Probe the three terminals of the cruise har ness connector first with the instrument panel switch in OFF then in the AUTO position In OFF position there should be no power to any of the three ter minals In the position center cavity B pink black wire test lamp should light 12 volts on meter and outer cavities A yellow wire and C red wire should NOT light In the On Auto switch position the amber indicator should light Engage Switch and Harness On or Off Car 1977 to 1979 The engage switch can be checked after disconnect ing it from the harness and performing the following tests with an ohmmeter Engage Switch On or Off Car Test 1970 to 1979 Indication Between Terminals 1 to 2 Yellow R 15 VI Electronic Cruise Control Engage Switch and Harness On or Off Car 1
17. on CODE 67 CRUISE CONTROL SHORTED SET OR RESUME CIRCUIT PERFORM SWITCH TEST CODE 76 AND CODE 76 OR CODE 77 PASS CODE 77 SET REFER TO THE APPROPRIATE CHART REFER TO CRUISE CONTROL CIRCUIT WHEN ALL DIAGNOSIS AND REPAIRS ARE COMPLETED CLEAR STORED CODES AND VERIFY PROPER OPERATION Figure 6 15 D F I Code 67 6 22 VI Electronic Cruise Control Code 71 Cruise Control Brake Circuit The Cruise Control brake circuit sends a 12 volt signal to the ECM except when the brake is depressed When the brake is depressed the switch is opened and the brake signal drops to 0 volts see figure 6 16 CRUISE VACUUM CPU GREEN IND ORN E CONNECTOR P CRUISE ON AMBER IND CRUISE E FUSE TO 0 5 YEL 3 0 ORN IGN 0 5 BLU DRK _ DZ CENTER BULKHEAD CONNECTOR Figure 6 16 Cruise Control Brake Circuit a Code 71 figure 6 17 indicates the brake signal doesn t switch from 12 volts to 0 volts when the brake is applied With the ignition on backprobe the Cruise Control brake switch connector circuits 904 and 919 with a test light connected to ground on each circuit If the test light lights on only one side of the switch then the Cruise Control brake switch does not have continuity and should be replaced if it is properly adjusted b If there is a light on both sides of the Cruise Control brake switch then the switch has continuity With the ignition on depress the brake pedal an
18. position the resume solenoid energizes and allows vacuum to enter the transducer The mechanical memory then adjusts the clutch orifice tube and valve assembly figure 2 3b to a position that re establishes vehicle speed when the brake was depressed above the low speed switch setting pheri hh pum Figure 2 3a Resume Type Transducer Spindle 2 3b Orifice Tube and Valve Assembly Assembly with Split Clutch System Diagnostics and Service System problems such as surging and cruise over under set speed are diagnosed and serviced in the same way as the non resume type system see Part An inoperative system requires a different service technique The following highlights the diagnostic and service procedure for an inoperative system Step 1 Disconnect the two terminal connectors at the transducer and re connect it so that the ENGAGE connector contacts the HOLD terminal figure 2 4 Figure 2 4 Reverse Two Terminal Connection 2 2 Resume Type Cruise Control Step 2 V Step 3 Step 4 Step 5 Turn ignition switch ON Do not start the engine Move the slider to the RESUME position hold momentarily and release If an engage thunk and release thunk are heard this portion of the electrical system is good Go to Step 4 Start the engine and check for vacuum at the hose connected to the manifold side of the RESUME VALVE If vacuum is present g
19. position toggle switch which controls power to the cruise control system When the switch is in the OFF position the system cannot be en CRU ISE CONTROL gaged When the switch is in the posi tion the amber light next to the words CRUISE CONTROL is lit and the system may be engaged with the switch located in the turn signal lever at any speed above approximately 25 mph When the system is en O N AUTO gaged a green light is illuminated adjacent to the word AUTO OFF Figure 6 7 Instrument Panel Switch 1980 to 1983 VI Electronic Cruise Control Cruise Engagement Switch 1979 1980 The engagement switch located within the turn signal lever has various modes of operation and is dependent upon the position of the instrument panel switch figure 6 8 With the instrument panel switch in the OFF position the system will not operate With the instrument panel switch in the CRUISE position the engagement switch operates as follows a Switch in Fully Released Position 1 System not engaged No function of the system will occur 2 System has been previously engaged Control voltage is being supplied to the servo unit solenoid valve from the electronic controller The unit solenoid valve regulates vacuum to the servo unit which maintains throttle position for desired speed b Switch Partially Depressed Detent Position The electronic controller is activated and a control voltage is su
20. wet pavement 6 21 VI Electronic Cruise Control Code 65 Cruise Control Circuit Coolant Temperature Exceeds a Maximum Limit Code 65 indicates that the Cruise Control was engaged and the coolant went overtemperature If the condition which set Code 65 is present then the Cruise Control will disengage See Section 6B in the Service Manual if the overtemperature condition persists Code 66 Cruise Control Circuit Engine RPM Exceeds a Maximum Limit Code 66 indicates that the Cruise Control was engaged and the engine speed exceeded a maximum allowable limit Whenever the condition which set Code 66 is present the Cruise Control will disengage Code 66 can be caused by removing the engine load placing the gear selector in neutral when the cruise control is engaged and operating Code 67 Cruise Control Circuit Shorted Set or Resume Circuit Figure 6 18 Code 67 indicates that the set coast or resume acceleration switches were improperly set when Cruise Control was engaged Whenever the condition which set Code 67 is present the Cruise Control will not operate during that ignition cycle To diagnose the system perform the switch tests If codes 76 or 77 set refer to the appropriate diagnostic chart If codes 76 and 77 of the switch tests pass then the system is OK Code 67 was caused by a failure in the set coast or resume acceleration circuits which was present when the cruise instrument panel switch was turned
21. 4 Gn TRAUS CRUISE SYSTEMS OME BE PUN RESUME 5 POR NAT E CRUISE CONTROL SYSTEMS Service Training 19006 00 4A CRUISE CONTROL SYSTEMS This booklet is supplied by GM Product Service Training to GM dealer service personnel upon their completion of the subject course conducted at GM Training Centers While this booklet will serve as an excellent review of the extensive program presented in the training center session it is not intended to substitute for the various service manuals normally used on the job The range of specifications and variation in procedures between carlines and models requires that the division service publica tions be referred to as necessary when performing these operations All information contained in this booklet has been furnished by AC Spark Plug Division and Cadillac Motor Car Division General Motors Corporation The information is based on the latest data available at the time of publication approval The right is reserved to make product or publication changes at any time without notice This booklet or any portion thereof may not be reproduced without written consent of GM Product Service Training General Motors Corporation Table of Contents Non resume Type Cruise Control General Operation Cruise System Components Component Functions
22. 980 and Later The turn lever engage switch can be checked after disconnecting it from the harness and performing the following tests with an ohmmeter Engage Switch On or Off Car Test 1980 and Later Indication Between Terminals Slide Depressed Pushbutton Depressed Eod ld If incorrect indications occur replace engagement switch and harness With one lead of ohmmeter connected to steering column mounting bracket check each terminal should show open If any indicate continuity a short exists and lever and harness must be replaced Move shift lever through full range when checking each wire Vacuum Control and Servo Unit Solenoid Valves a Resistance Test Engine Off Step 1 Disconnect electrical connector at solenoid valve being tested Step 2 Connect ohmmeter to solenoid valve terminals Step 3 Measure resistance it should be between 37 and 48 ohms on servo unit valve and between 23 5 and 27 5 ohms on vacuum control valve Step 4 f reading is outside of limits replace appli cable valve b Functional Test Engine Off Step 1 Disconnect electrical connector at valve being tested Step 2 Connect a jumper wire from the positive ter minal of the battery to one terminal of the valve being tested Step 3 Step 4 Connect another jumper wire to ground Brush the other end of the grounded jumper wire across the remaining terminal of the valve You must hear the vacuum control valve or servo u
23. E IF O K REPLACE CRUISE BRAKE PEDAL BACKPROBE CONTROL BRAKE SWITCH THE CRUISE CONTROL BRAKE RELEASE SWITCH CONNECTOR CIRCUIT 919 WITH A TEST LIGHT TO GROUND CHECK FOR A SHORT TO GROUND IN CIRCUIT 904 919 903 917 916 REPAIR OPEN IN CIR CUIT 904 NO LIGHT CHECK FOR AN OPEN IN CIR CUIT 919 REPLACE CRUISE OK NOT OK CONTROL BRAKE RELEASE REPLACE FUSE REPAIR SWITCH IF FUSE BLOWS AGAIN REPLACE ECM WHEN ALL DIAGNOSIS AND REPAIRS ARE COMPLETED CLEAR STORED CODES AND VERIFY Nap PROPER OPERATION CHECK FOR FAULTY ECM CONNECTOR OF FAULTY ECM REFER TO CRUISE CONTROL BRAKE CIRCUIT Figure 6 17 D F I Code 71 6 25 VI Electronic Cruise Control o 26 RR GENERAL MOTORS CORPORATION Product Service Training va e LITHO IN U S A
24. FIER VENT LRN 7 SOLID STATE T 5 PNK BLK eer man GROUND POWER CRUISE SERVO SOLENOID SEE GROUND m 5471 p ISPEEDSIGNAL 8 VOLT I CONTROLS VACUUM TO DISTRIBUTION INPUT REFERENCE crouno CRUISE SERVO key LT GRN 995 VACUUM TO THROTTLE 3 BLK 151 Y ios LT GRN M 995 BLK B 931 962 SUPPLY 8BLK 151 8 BLK B 151 LINKAGE 5 151 6 711 C711 UN LI DIESEL 225 un GRN 435 3 BLK 151 SOLID STATE SPEED SPEED a COMMAND CONTROL V6 2 SENSOR SENSOR e W di CHECK ENGINE 2 3 NE 55 c2 LIGHT Figure 6 10 Cruise Schematic Diagram VI Electronic Cruise Control HOT IN RUN CRUISE CONTROL CRUISE RELEASE SWITCH OPENS WITH CONTROL BRAKE PEDAL SWITCH DEPRESSED 5 LT BLU BLK 5 GRN CRUISE CRUISE ON ENGAGE INDICATOR INDICATOR 5 BLK 151 5 LT BLU SEE GROUND 8 DK GAN 5222 BLK 3 BLK 151 5 DK GAN 6113 919 02 C1018 5 DK BLU 403 8 WHT BRAKE INPUT CRUISE CONTROL 5 DK GRN 919 CRUISE ENGAGE POWER UNIT SOLID STATE ENABLE OUTPUT SOLENOID VALVE OUTPUT 7 10 VACUUM 3 C715 CONTROL VALVE 403 SOLENOID 35 LT GRN 402 VEHICLE C1018 SPEED SENSOR 5 LT GRN 402 CZ 5 DK BLU WHT POWER UNIT 403 SOLENOID VALVE 8 BLK 151 G132 6 11 6 12 Figure 6 11 D F I Cruise Schematic Diagram VI
25. FUSE SWITCH p HOLD 4 TERMINAL l Figure 1 24 Check the Part Number for Vehicle a amp Application gs E LOW SPEED SWITCH TRANSDUCER PORT p di A CRUISE LAMP CIRCUIT PORT B SOLENOID NOT ENERGIZED 3 lg 3 90000000 If transducer repair is required it must be per 3 formed by an authorized transducer repair facility as listed in the applicable AC Delco repair bulletins TO VACUUM SOURCE Figure 1 25 AC Cruisemaster system Non resume Type Electrical System Schematic KEY HOLDIN Non Resume Type Cruise Control Non Resume Type Cruise Control NOTES Non Resume Type Cruise Control l Non Resume Type Cruise Control ROTATION WITH SPEED INCREASE m a ue ro o i I I P d i 2277 VARIABLE T PORT C Z 29 CLUTCH gt Kt LOW pese SPEED IFILTERED AIR S sWITCH I d 0 Le aM L BA AG 56 i IEN l 5 gt Sa pw VACUUM SHUT OFF VALVE Fon MESE EPE ALL 4 H PORT A Nt NOT im feet lo decur NANG Li a X PORT B AIR FILTER N TO VACUUM T SOURCE TRANSDUCER BRAKE 9 en PEDAL VACUUM
26. INSERT VALVE ASSEMBLY INTO TUBULAR CRUISE CONTROL UNTIL VALVE BODY SEATS TUBULAR RELEASE SWITCH PULL BRAKE PEDAL REARWARD AGAINST VACUUM RELEASE VALVE AND INTERNAL PEDAL STOP VALVE ASSEMBLY TORQUE CONVERTER CLUTCH WILL BE MOVED IN TUBULAR CLIP PROVIDING RELEASE SWITCH PROPER ADJUSTMENT Figure 6 5A Cruise Control Brake Valve and Figure 6 5B Cruise Control Brake Valve and Release Switch E and K Release Switch Except E and K VI Electronic Cruise Control Instrument Panel Switch 1977 to 1979 This switch is located on the instrument panel to the left of the steering column adjacent to the headlamp switch The three position toggle switch figure 6 6 controls the electrical power to the cruise control system When the switch is in the position the system cannot be engaged When the switch is in either CRUISE or AUTO the amber light to the right of the words CRUISE CONTROL is lit and the system may be engaged with the switch located in the turn signal lever at any speed above approximately 25 mph When the system is engaged a green light is illuminated adjacent to the words AUTO and CRUISE Available Function CRUISE CONTROL Switch Position bas AUTO AMBER nw GREEN OFF FILTER Cruise Cruise Memory Resume Advance Cruise System Off Cancel Memory Figure 6 6 Instrument Panel Switch 1977 to 1979 Instrument Panel Switch 1980 to 1983 This is a two
27. ONNECTOR and to the VACUUM PUMP The 035 inch restriction in the hose connector between PORT and the VACUUM PUMP keeps the volume of air relatively small Whenever manifold vacuum at PORT C dropstoa level lower than the vacuum at PORT pump output the 3 PORT CHECK VALVE closes PORT The change in vacuum level and closing of PORT is caused by heavy load operation Under heavy load the system will now operate off the vacuum pump Air flow is shown by the double arrows in figure 4 1 VACUUM _ TO INTAKE PUMP MANIFOLD Avec 035 RESTRICTION CONNECTOR ena EGR PORT P N lt 3 PORT TO BRAKE CHECK VALVE BOOSTER pf PORT ei 2 PORT A TO TRANSDUCER RESUME VALVE Figure 4 1 Vacuum Assisted System for Heavy Load Cruise Operation 4 1 sas w IV Vacuum Assisted Systems System Diagnostics The vacuum assisted system does not require periodic maintenance However the following diag nostic and service procedures are applicable e If the 3 port check valve is blocked closed or blocked open the system will cruise below en gagement speed or system surging will occur e f the 3 port check valve is incorrectly connected the cruise system will either be inoperative or will cruise below engagement speed To correct cruise engagement or cruise operation below engagement speed complaints clean the check valve and connection
28. OR AN OPEN A SHORT SOLENOID A SHORT TO GROUND TO GROUND CHECK FOR FAULTY ECM CONNECTOR OR FAULTY ECM CHECK FOR FAULTY ECM CONNECTOR OR FAULTY ECM REFER TO CRUISE CONTROL CIRCUIT Li WHEN ALL DIAGNOSIS AND REPAIRS ARE COMPLETED CLEAR STORED CODES AND VERIFY PROPER OPERATION Figure 6 14 D F I Code 63 6 20 VI Electronic Cruise Control Code 63 Cruise Control Circuit Car and Set Speed Tolerance Exceeded Figure 6 14 Code 63 indicates that the Cruise Control was engaged at a certain set speed and the vehicle speed was more than 20 miles per hour above or below this set speed Whenever the condition which set Code 63 is present the Cruise Control will disengage a Code 63 may result from operator error or a system malfunction To diagnose a system malfunction pro ceed as follows Step1 Start engine momentarily disconnect 6 pin weatherpack connector at the rear of the fuel tank engine will stall Step2 Turn cruise enable on Step 3 Enter diagnostics and display 9 6 for output cycling Check the cruise control vacuum and power valves to determine if they cycle click on and off If the vacuum and power valves are OK check for binding linkage If the linkage is not binding check for vacuum leaks or blockages If there are no vacuum problems then the system is OK b If the vacuum valve does not cycle disconnect the vacuum valve connector and connect a test light be tween the harness
29. RAKE gt HERE ZIN RESISTANCE IRE BATTERY tin TO THROTTLE ENGAGE FAIR CONTROL gt VACUUM RELEASE VALVE e Fg 9m SPEED rs SWITCH VACUUM SOLENOID VALVE lt iium TRANSDUCER L BRAKE LIGHT SWITCH CIRCUIT lt y on RESUME SOLENOID kon COIL FROM MANIFOLD VACUUM pon PLUNGER RESUME VALVE Figure 2 9 Schematic RESUME OPEMATIO a lt lt LZ A A gt o fadt le C Cet DAAAM LAZA yon PLE tot gu Eg Ta ota e LEA 5 Me x EA ae LX et Lig dans Se A ata c vo la SAK ME ALA Anyen A AE Il Resume Type Cruise Control Resume Type Cruise Control YEAR ONLY The 1982 General Motors J cars feature an aspirator assisted vacuum system for cruise control operation is designed to supplement engine vacuum when the engine is under load such as traveling up a steep grade The aspirator assisted vacuum system consists of an ASPIRATOR a 3 PORT CHECK VALVE a 2 PORT CHECK VALVE an AIR PUMP and an AIR MANAGEMENT VALVE Note that air for the ASPIRATOR is connected to the same air line that connects the AIR PUMP to the AIR MANAGEMENT VALVE Also note that the bottom of the 3 PORT CHECK VALVE leads to the cruise
30. RT A and PORT VIEW A PORT BLOCKED CRUISE NOT ENGAGED CUP SHAPED VACUUM PORT A w VALVE TRANSDUCER HOUSING PORT A CUP EA m SHAPED VACUUM EE VALVE PORT VIEW B PORT A AND PORT COMMON VACUUM CRUISE ENGAGED Figure 1 12 Cup Shaped Vacuum Valve Positioning 1 7 Type Cruise Control When the solenoid is energized engine vacuum ap pears at the SERVO and the VACUUM BRAKE RE LEASE VALVE However the amount of vacuum present must be precisely controlled PORT isa variable orifice and is the control mechanism that maintains or adjusts vacuum level in the system in cluding the SERVO The variable orifice PORT consists of an orifice tube and valve assembly It is essentially an air meter ing valve that consists of a sliding valve orifice tube and a wishbone type clutch spring figure 1 13 A rubber clutch is secured to a spindle shaft figure 1 13 When the system is not in use a solenoid oper ated mechanism fold out figure 1 26 spreads the wishbone shaped clutch spring which allows the rubber clutch to rotate within the clutch spring When cruise control operation is engaged the CAM allows the wishbone shaped clutch spring to close and hold the rubber clutch Essentially the rubber clutch works similar to a speedometer pointer It ro tates clockwise or counterclockwise in p
31. SDUCERS The electrical and pneumatic circuits of diesel and gasoline transducers are similar The diagnostic and service techniques presented in Part and Part should be followed However there are some special considerations in servicing diesel cruise control systems 1 The diesel vacuum source is an engine driven vacudm pump figure 5 2a xcontrolled by vacuum regulator figure 5 2b Regulated vacuum output is a GOHBIA 2 7 inches Hg FU t vac CAC Su ERRATIC OFT TION VACUUM PUMP REGULATOR a Typical V 8 Diesel System Vacuum Vacuum Regulator Pump 5 1 V Diesel Transducer Non resume and Resume Systems 2 diesel transducers have an orifice cup in PORT of the transducer clutch housing assembly figure 5 3 Figure 5 3 Orifice Cup in Diesel Transducer at PORT A NOTE If transducer repair is required it must be per formed by an authorized transducer repair facility as listed in the applicable AC Delco repair bulletins 5 2 1977 CAP fer a a VI Electronic Cruise Control P Can 99 929 9 Le dcc PR D Non D F l Digital Fuel Injection and Computer Integrated Cadillac General Description Figure 6 1 illustrates Electronic Cruise Control system components Cruise Control is a speed control system that uses manifold vacuum or vacuum from a vacuum pump to actuate the throttle pow
32. TCH SPEED SENSOR amp P ELECTRONIC CONTROLLER VACUUM CONTROL VALVE P SWITCH VACUUM RELEASE SERVO POWER UNIT amp VACUUM VACUUM SOLENOID VALVE BRAKE SWITCH CONTROL VALVE RELAY Figure 6 1 AC Electronic Cruise Control Components zlte co 4 gt IR 7 ri 7 A dat o poe a m Me 2 THS SECTION ONLY s VI Electronic Cruise Control Component Operation Electronic Controller D F I Digital Fuel Injection Only Cruise Control operation is one of the many functions which the ECM controls The ECM receives input signals from the Cruise Control engagement switches the instrument panel switch the brake release switch the drive switch and the speed sensor The ECM processes these Cruise Control inputs together with the engine control information and transmits command signals to the vacuum control solenoid valve to provide vacuum to the system and servo unit solenoid valve to control vehicle speed The electronic control module receives signals from the cruise engagement switch instrument panel switch electric brake release switch and speed sensor It processes this information and transmits command signals to the vacuum control valve to provide vacuum to the system and servo unit solenoid valve to control vehi
33. UE 1 1 Altick NT Non Resume Type Cruise Control The cruise control function is disengaged whenever the brake pedal is depressed figure 1 3a To re engage the cruise function the driver merely accelerates to a speed above 30 mph and then fully depresses and slowly releases the control switch button To cruise at a higher speed after cruise control has been engaged the driver accelerates to the higher speed and then fully depresses and slowly releases the control switch button To cruise at a lower speed fully depress the control switch button and hold it until the vehicle has decelerated to the desired lower speed Slowly releasing the control switch button re engages the cruise function When the cruise function is engaged depressing the accelerator will override the system allowing vehicle speed to increase figure 1 3b Releasing the accelerator pedal allows speed to decrease until it reaches the previously selected lower cruise speed The cruise system will then automatically maintain the previously selected speed Figure 1 3a The Brake Disengages the System Figure 1 3b The Accelerator Overrides the System Tr 9 l Non Resume Type Cruise Control Cruise System Components The major components of the AC Cruisemaster System are the engage switch transducer assembly servo and linkage vacuum and electric cruise rel
34. a physical inspection of the en gine compartment Look for disconnected or pinched vacuum hoses figure 1 17 hoses that could be pinched closed when the hood is down cracked or spongy hoses especially in high heat areas leaky servo missing or disconnected components sure check manifold fitting check brake pedal vacuum re lease valve for proper operation Figure 1 17 Physical Inspection of the Vacuum System Step 2 Check the servo for leaks a Shut off the engine b Disconnect the vacuum line at the servo c Push the servo diaphragm fully inward and hold figure 1 18a d Use a finger or thumb to tightly cover the servo vacuum fitting and release the diaphragm figure 1 18b The diaphragm should remain depressed If it expands a leak is present replace the servo unit Figure 1 18a Depress Servo Diaphragm Figure 1 18b Cover Vacuum Port and Release Finger Pressure on Diaphragm Type Cruise Control Step 3 Step 4 Figure 1 19 Reverse Electrical Connector Harness to Bypass Low Speed Switch Step 5 Step 6 Figure 1 20 Pressing the Cruise Control Switch Button should Engage the Solenoid Check for a blown fuse If the fuse is good go to Step 4 the electrical connection at the transducer figure 1 19 Reconnect so that the ENGAGE wire in the harness mates with the HOLD terminal on the transducer This byp
35. asses the low speed Switch Turn ignition switch Do not start the engine Slowly depress and slowly re lease the cruise control switch Listen for a solenoid engagement thunk thunk sound figure 1 20 If the thunk is heard on engagement and release the solenoid coil and related circuits are electrically good If the thunk is erratic or not heard go to Step 6 Check the brake activated electric release switch A misadjustment could be the cause of the problem De press brake switch in increments At each point attempt system engagement with the cruise control switch until en gagement 15 no longer possible travel for the engagement interval should be about Adjust the brake switch as required Note that the brake pedal can hang up This must be considered whenever brake switch adjustment is performed If the transducer does not engage per form the following basic electrical checks 6a Check to make sure all electrical connectors and terminals are free of grime and corrosion 6b See fold out figure 1 25 Disconnect the harness at POINT A Connect a voltmeter to the hot side at POINT A Type Cruise Control Step 7 Step 8 6c With the ignition on battery voltage should be indicated on the voltmeter If voltage is not shown go to 6d voltage is present go to 6e 6d Usethe voltmeter t
36. bead chain or linkage This increases the car buretor throttle opening to maintain the desired cruise speed SERVO C VACUUM UC 760 SPRING FULLY THROTTLE COMPRESSED ORIFICE WINDOWS COMPLETELY CLOSED Figure 1 15 Orifice Window Closes to Compensate for Speed Reduction If vehicle speed tends to increase such as on a downgrade the valve moves to increase the size of the window openings in the orifice tube figure 1 16 A larger volume of bleed air is admitted at the servo which reduces the vacuum level The servo dia phragm relaxes the tension on the bead chain or link age to reduce the carburetor throttle opening In this Way cruise speed is maintained on a downgrade SERVO NN zi THROTTLE VACUUM lt gt SPRING RELAXED ORIFICE WINDOWS COMPLETELY OPEN Figure 1 16 Orifice Window Opens to Compensate for Speed Increase Non Resume Type Cruise Control System Diagnostics and Service The symptoms requiring diagnosis and service are A CRUISE SYSTEM INOPERATIVE B CRUISES OVER or UNDER SET SPEED and C SURGING The proper diagnosis and correction procedure for each of the three symptoms is described in the following paragraphs However reference to the vehicle model service manual procedure is also necessary The proper diagnosis and correction procedure for each of the three symptoms is described in the following paragraphs A Cruise System inoperative Step 1 Perform
37. ch Switch Resume System Only figure 1 9 1981 and later model vehicles equipped with a lock up torque converter locking clutch trans mission use a combination vacuum release valve and cruise release electric switch assembly When the brake pedal is depressed the vacuum release valve disengages the cruise function At the same time the contacts in the electric switch open which disengages the locking clutch mechanism in the transmission The locking clutch system will remain disengaged after the brake pedal is re leased The system remains disengaged until the electronic control module signals re engagement See figure 1 9 Whenever the vacuum release valve is adjusted it also adjusts the position of the lock up torque converter clutch switch 6 Upper and Lower Cable and Casing Assemblies figure 1 10 The upper cable and casing assembly connects the transducer to the speedometer The lower cable and casing assembly connects the transmission driven gear to the transducer UPPER CABLE amp CASING ASSEMBLY TRANSDUCER SPEEDOMETER LOWER CABLE amp CASING ASSEMBLY Figure 1 10 Upper and Lower Cable and Casing Assemblies 1 5 ee gt _ gt gt gt _____ ____ Non Resume Type Cruise Control Electrical and Vacuum Operation Figure 1 27 is combined electrical vacuum system schematic of the non resume type cruise control system Figures 1 25 and 1 26 show the electrica
38. cle speed Speed Sensor Circuit Only The speed sensor consists of a light emitting diode and a photo transistor enclosed in one connector which attaches to the back of the speedometer cluster adjacent to the speedometer cable figure 6 2 The photo transistor generates an electrical signal corre sponding to vehicle speed when it is exposed to re flected light from the light emitting diode The photo transistor is activated by reflected light from each VEHICLE SPEPD SENSOR passing bar of the rotating speedometer drive mag L E D AND PHOTO CELL net The surface of the drive magnet is highly reflec tive to enhance the reflection of light to the photo transistor and the surface of the speed cup has a dull finish which inhibits erroneous reflections The light from the light emitting diode is not visible to the human eye because it is part of the infrared spectrum of light The speed sensor produces a weak voltage signal and Figure 6 2 Vehicle Speed Sensor Buffer must be used for several speed inputs Therefore the Amplifier D F I buffer amplifier is placed between the speed sensor and the ECM to and distribute the speed sig nal The buffer amplifier also inverts this speed signal so the signal will be in a format which is understood by the ECM On DFI the speed sensor is on all cars for ECM usage cruise control uses buffer amplifier output 6 2 VI Electronic Cruise Control
39. connector pins while performing the output cycling tests If there is no light check circuit 919 or 403 for an open If the wiring is OK check for a faulty ECM connector or faulty ECM c If there is a steady light check circuit 403 for a short to ground If the circuit is OK check for a faulty ECM connector or faulty ECM d If the light is on for 3 seconds and off for 3 sec onds then the ECM and wiring harness are OK re place the vacuum valve solenoid e If the power valve does not cycle disconnect the power valve connector and connect a test light be tween the harness connector pins while performing the output cycling tests If there is no light check circuits 402 and 151 for an open or circuit 402 for a short to ground If the circuits 4402 and 151 are OK check for a faulty ECM connector or faulty ECM f If there is a steady light check circuit 402 for a short to voltage If circuit 402 is OK check for a faulty ECM connector or faulty ECM g If the light flashes continuously then the ECM and the harness are working properly replace the power valve solenoid Code 64 Cruise Control Circuit Vehicle Acceleration Exceeds Maximum Limit Code 64 indicates that the Cruise Control was en gaged and the vehicle acceleration exceeded the pre set rate which was programmed into the ECM If the condition which set Code 64 is present then the Cruise Control will disengage Code 64 could be caused by icy or
40. d backprobe the Cruise Control brake switch circuit 919 with test light to ground If the test light continues to glow replace the Cruise Control brake switch because it is shorted VI Electronic Cruise Control c If the test light does glow then the switch is functioning properly Check circuit 919 for open If circuit 919 is OK check for a faulty connector or faulty because it is not processing a good brake release signal d Check the 3 amp cruise fuse If it is OK then repair an open in circuit 904 e If the Cruise Control fuse is not OK then there is a short circuit to ground in the wiring harness or the ECM Check circuits 904 and 919 for a short to ground Engaging the cruise instrument panel switch the set resume Switch or the resume acceleration switch can blow the cruise fuse This situation would occur if circuits 903 916 or 917 have a short to ground on them If the wiring harness is OK and the fuse blows again check for a faulty ECM connector or faulty ECM because it is internally shorted VI Electronic Cruise Control CODE 71 CRUISE CONTROL BRAKE CIRCUIT RETEST SWITCH FUNCTION WITH IGNITION ON BACKPROBE THE CRUISE CONTROL BRAKE SWITCH CONNECTOR CIRCUITS 4904 AND 4919 WITH A TEST LIGHT TO GROUND LIGHT ON BOTH SIDES NO LIGHT LIGHT ON ONE SIDE CHECK FOR PROPER ADJUSTMENT IGNITION ON CHECK 3 AMP 4 WHILE DEPRESSING THE CRUISE FUS
41. d vehicle should start to slow down Allow vehicle to slow to approximately 45 mph using brakes if desired Momentarily depress slide switch on 1981 and later or on 1977 1980 units depress en gagement switch button to detent position and release Vehicle should accelerate at a controlled rate and resume previously set speed of 55 mph and maintain that speed Green light should come on when slide or button is released Step 8 Push engagement switch button all the way in and hold Green light should go out Coast to 50 mph Release button to engage system at 50 mph green light should come on and vehicle should maintain that speed Step 9 Preliminary Inspection Make sure all test equipment such as test lights and voltmeters are in good working order prior to using them a Electrical and Vacuum Inspection Fuse Inspect Cruise Control fuse and replace as necessary b Electric Brake Release Switch Engine Off On Car Check Step 1 Turn ignition ON and instrument panel switch to or CRUISE position Step 2 Connect test light or voltmeter to ground Step 3 Probe Feed wire at connector lamp should light 12 volts on meter indicating proper feed Check switch adjustment with probe still at Feed wire depressing brake pedal V2 should turn out light no voltage on meter If lamp in 3 did not light probe wire in adja cent connector cavity If probe lights 12 volts on m
42. ease switches the upper and lower cable and casing assemblies wiring harness and vacuum lines figure 1 4 UPPER CABLE amp CASING ASSEMBLY M aswaa M VACUUM RELEASE SERVO VALVE PUSH BUTTON CONTROL SWITCH a d ELECTRIC RELEASE SWITCH LOWER CABLE amp CASING ASSEMBLY Figure 1 5 Cruise Control Lever with Engage Switch Button 1 3 Component Functions 1 Cruise Control Switch figure 1 5 This driver operated control is conveniently mounted on the end of the turn signal handle or the gear shift selector lever The driver operated functions of the cruise control switch have been previously described in detail on page 1 1 RUNG r n s n E Los Ae by rototire ES dd MO ped jwen P 2 Transducer figure 1 6 The transducer is a combination speed sensing device and control unit It contains a low speed Switch that prohibits cruise control operation at low speeds This switch is calibrated at approxi mately 30 mph When the cruise control function is engaged the transducer senses vehicle speed and controls the vacuum level to the servo to maintain the cruise speed selected 2 7 2 a lie Mas dic di ae dv cid L v Amas peek lt fi UZ Pref ar pea 7 l s BAS anochs A Pn 3 Servo
43. ed through the C C FUSE to the CRUISE CON SWITCH With the control switch in Auto Cruise current flows through the amber CRUISE ON INDICATOR to ground Voltage is now available through terminal D on the control switch and the BRAKE SWITCH and applied 1 through the green CRUISE ENGAGE INDICATOR to terminal B of the CRUISE CONTROLLER 2 to terminal H of the CRUISE CONTROLLER and 3 through the ENGAGE SWITCH ASSEMBLY to terminal E or D of the CRUISE CONTROLLER The CRUISE SERVO SOLENOID controls the amount of vacuum applied to the CRUISE SERVO This sole noid has no effect on the CRUISE SERVO however until the CRUISE VACUUM SOLENOID is open The CRUISE VACUUM SOLENOID is open to let vacuum pass through only when the system is engaged The VEHICLE SPEED SENSOR sends a variable signal to the CRUISE CONTROLLER based on car speed When car speed is over about 25 mph the CRUISE CONTROL system can be engaged With the CRUISE CONTROL SWITCH in Auto Cruise the system is engaged by briefly pressing the Set Coast lock in button The CRUISE CONTROL LER then lets current flow through terminal C and the CRUISE VACUUM SOLENOID to ground This opens the CRUISE VACUUM SOLENOID and vacuum is supplied to the CRUISE SERVO SOLENOID The CRUISE SERVO SOLENOID is operated by current through CRUISE CONTROLLER terminal F Signals from the VEHICLE SPEED SENSOR vary that current when car speed changes These variations
44. eed switch contacts are closed the cruise system can now be engaged The coil engages with a distinct thunk sound Refer to the electrical schematic figure 1 25 When the engagement switch button is released current A flow through the 40 OHM RESISTANCE WIRE is suf Figure 1 11 Low Speed Switch Operating ficient to hold the SOLENOID in the engaged Circuit position Cruise Lamp Some models of the cruise system feature a CRUISE figure 1 25 When the SOLENOID is en gaged it provides a ground for the cruise lamp There fore when cruise control is engaged the cruise lamp will illuminate Non Resume Type Cruise Control Vacuum Operation Open the fold out page Vacuum System Schematic figure 1 26 page 1 18 The following paragraphs describe the vacuum operation of the AC Cruisemaster system Trace and follow the circuit operating description on the schematic drawing Assume the vehicle is operating at 50 MPH and the cruise control is not engaged Vacuum from the engine manifold is blocked off at PORT B of the TRANSDUCER figure 1 12 VIEW A cup shaped valve which is part of the SOLENOID assembly is positioned to block PORT also see figure 1 11 When the cruise control is engaged the solenoid energizes moving the cup shaped valve upward to also cover PORT figure 1 12 VIEW With both ports covered common vacuum is developed across PO
45. ep 8 Switch Condition Terminal End Connections Buon so ra 24 Off Released Off Resume Released Resume C Cruise IReleased O O Coast Half Depressed Coast Fully Depressed Set Releasing Open Continuity Use an Ohmmeter and check the resistance wire and transducer solenoid coil figure 2 8 e The resistance wire should be between 20 25 Ohms e The transducer solenoid should be ap proximately 6 Ohms Make sure the trans ducer has a good ground to the vehicle chassis e f no defect is found replace the transducer NOTE If transducer repair is required it must be performed by an authorized trans ducer repair facility as listed in the ap plicable AC Delco repair bulletins ALY en Il Resume Type Cruise Control it ns ag tr RESUME ue 2c e pum iar i e Sra Le AND IM VAC UP RANS GAI 2 5 a fin AA 7 E 4 2 2 Bunt 2 de 52 7740 tem L4 E gt xxx s La A Dey PE f Ot Resume Type Cruise Control ENGAGE SWITCH iie gt PUSH BUTTON IN NORMAL 1 i POSITION SLIDER IN SET POSITION SLIDER SHUTTLE ad 4 PUSH BUTTON F IGNITION SWITCH FUSE Em NOTE B
46. er unit or servo The servo unit moves the throttle when its diaphragm is subjected to varying amounts of vacuum The amount of vacuum to the servo unit is controlled by a solenoid valve which constantly modulates vacuum to the servo unit in response to commands from the electronic controller or fuel ECM The controller receives signals from the engagement and instrument panel switches electric brake release switch and speed sensor The speed sensor is located on the back of the speedometer cluster and provides signals representative of car speed to the control system wire harness connects the speed sensor to the electronic controller Input signals received from the sensor by the controller or ECM are used to control the servo unit solenoid valve which regulates the amount of vacuum to the servo unit to control the speed of the car two or three position off on auto or cruise switch located on the instrument panel and an engagement switch located at the end of the turn signal lever control the operation of the system Two systems for brake release are provided 1 electric switch mounted on the brake pedal support cancels the controller signal by shutting off the system and venting the servo unit to atmosphere through the servo unit solenoid valve 2 vacuum release valve also is mounted on the brake pedal bracket and vents the servo diaphragm to atmosphere as a second disengagement system TURN SIGNAL LEVER ENGAGEMENT SWI
47. eter adjust or replace switch as necessary If no light or 12 volts wiring to switch is faulty refer to wiring diagrams in this section c Off Car Check Step 1 Use ohmmeter or self powered test light Step 2 Step 4 Step 5 With switch plunger extended meter should read infinity open circuit Test light OFF Step 3 With switch plunger fully depressed meter should indicate continuity Test light ON Instrument Panel Switch 1977 to 1979 a On Car Check Switch Engine Off Step 1 Turn ignition ON Step 2 Step 3 Connect test light on voltmeter to ground Disconnect the 3 wire connector from the turn signal lever engage switch harness to the cruise harness connector gt VI Electronic Cruise Control Step4 Probe the three terminals of the cruise har ness connector first with the instrument panel switch in OFF then CRUISE and finally in the AUTO position In either Cruise or Auto switch positions the amber indicator should light The checks should indicate the following Instrument Panel Switch On Car Test 1977 to 1979 Test Light Instrument Indication at Terminal Panel Switch Position Instrument Panel Switch Off Car 1977 Ww to 1979 Step 1 Refer to Service Manual for removal and in stallation of the switches Use ohmmeter or self powered test light Step2 Identify printed circuit terminals from letters A thru H on harness connector Letters read
48. he ECM One of the ECM Functions is to combine the Cruise Control input sig nals and the DIGITAL FUEL INJECTION engine control information It then sends command signals to the VACUUM CONTROL VALVE SOLENOID and POWER UNIT SOLENOID VALVE The CRUISE SERVO SOLENOID VALVE controls the amount of vacuum applied to the CRUISE SERVO This has no effect on the CRUISE SERVO however until the VACUUM CONTROL VALVE is open The VACUUM CONTROL VALVE is open to let vacuum pass through to the power unit only when the system is engaged When the control switch is in Auto On and the vehi cle speed is above 25 mph the system can be en gaged by depressing the Set Coast button in the En gage Switch Assembly Current will flow through the switch to the ECM as the Set Coast Input signal When the button is released the ECM sends a Cruise Engage signal to operate the VACUUM CONTROL VI Electronic Cruise Control VALVE SOLENOID and CRUISE ENGAGE INDICATOR The ECM will operate the CRUISE SERVO SOLENOID VALVE with the Power Unit Solenoid Valve input sig nal to maintain the selected speed Once the speed has been set depressing the gas pedal will increase car speed Releasing the gas pedal lets the car coast back down to the set speed The Cruise Control set speed does not change by speed ing up unless the Set Coast button is depressed If the driver depresses the Set Coast button and releases the gas pedal at the same time then the thr
49. in current change the amount of vacuum the CRUISE SERVO SOLENOID applies to the CRUISE SERVO The CRUISE SERVO keeps the set speed The CRUISE CONTROLLER also applies ground to the green CRUISE ENGAGE INDICATOR through terminal B The indicator goes on Once the speed has been set depressing the gas pedal will increase car speed Releasing the gas pedal lets the car coast back down to the set speed The Cruise Control set speed is not changed by speeding up unless the Set Coast lock in button is pressed Set speed can be reduced by pressing and holding the Set Coast button This breaks the circuit through controller terminal C The CRUISE VACUUM SOLE NOID closes and the CRUISE SERVO no longer gets any vacuum The car coasts to a lower speed This speed becomes the new set speed when the button is released If the Resume Accel slide switch is moved and held the car will speed up When it is released a new set speed is established If after braking the slide switch is moved and released the car will resume the previ ously set speed memory speed The BRAKE SWITCH will disengage the set speed but not the memory speed setting You must turn off the control switch or the IGNITION SWITCH or set another cruise speed using the Resume Accel slide switch to erase the memory speed setting VI Electronic Cruise Control VI Electronic Cruise Control rf ky f BRAKE SWITCH E CT l i OPEN WITH 4 EM
50. ion it will dis engage the cruise control function It will remain dis 1 DEPRESS FULLY TO DISENGAGE engaged as long as held depressed When the button 2 PARTIAL RELEASE TO ENGAGE 3 FULL RELEASE CRUISE REMAINS ENGAGED is partially released it engages cruise control When the button is released the cruise control function re mains engaged Some GM vehicles feature an ON OFF switch On these models the cruise control function may be dis engaged by placing the switch in the position Figure 1 2 Operation Control Positions mA dedi OH OFF Aro TS AT At n di Li E ef CO ecc gt bouk f CH MAL _ o Hare pen EL P Rei Sasa Od ac M CEA A aad dd gt gt ie LA ut lo 724 a l A C2 E aper yi A gt Q f re gt Eee P B PE A VA tao pliz eap gt L x P MVOM om AIRE 3 C hace AL aa lt Lez lt n za E TA 2 te leya Z MTM MC pf LOMA ALMAY LA es Lee tse Tag 2 A 4 lan gt 42 lt f fte Sa P A ie MA ray AE a E 7 c vw jiee AGE Qe X HET RS vg gt tere tas ALE LE ELLE ipaa s PECOLATOR VAL
51. l and vacuum systems separately Electrical Operation Open the fold out page Electrical System Schematic figure 1 25 page 1 15 The following paragraphs de scribe the electrical operation of the system Trace and follow circuit operation on the schematic drawing Current from the positive side of the BATTERY B flows through the IGNITION SWITCH FUSE closed BRAKE RELEASE SWITCH to the CRUISE CONTROL SWITCH When the CRUISE CONTROL SWITCH is in the AT REST position current flows through the switch the 40 OHM RESISTANCE WIRE and to the HOLD terminal on the TRANSDUCER The voltage at the HOLD terminal is now quite low due to the voltage drop across the 40 Ohm resistance This voltage is also applied to the SOLENOID COIL in the transducer but it is not sufficient to energize this coil Low Speed Switch Operation figure 1 11 The transducer contains a rubber clutch with an operating arm The clutch and arm rotate similar to a speedometer pointer needle At speeds below approx imately 30 MPH the clutch arm holds the low speed AE switch contacts open ET is cc EA If the cruise control switch is depressed at speeds under 30 MPH the low speed switch contacts are held open by the clutch arm cruise can not be engaged At speeds above about 30 MPH the rubber clutch arm rotates which allows the low speed switch contacts to close see dotted line figure 1 11 When the low sp
52. mber light should be on to confirm power supply Step 3 Controller There should be no attempt made to repair the elec tronic cruise controller Check to make sure connec tors are fully seated Red 8 way and red 3 way speed sensor If all other components have been checked and found to be functioning properly then replace the controller Speed Sensor Check On Engine Off Step 1 Turn ignition on and Cruise dash switch to ON AUTO position Step 2 Refer to Service Manual for partial removal of the speedometer cluster for access to the speed sensor 3 way connector located on the electronic controller Connect voltmeter between ground and No 2 black terminal Note and record this voltage reading Should read voltage between 9 and 11 volts This is less than full battery voltage because of the internal circuitry of the electronic controller If voltage is outside of limits replace the controller Step 3 Connect voltmeter between ground and No 3 red terminal Voltage should be 1 to 2 volts less than value in terminal No 2 This is the voltage drop through the light emitting diode If voltage is outside of limits replace the speed sensor Step 4 Connect voltmeter between ground and No 1 terminal green wire Roll car forward while checking voltage Voltage should fluc tuate at least 5 volts from low points to peaks output of photo transistor and each peak should be within 1 volt of reading at No
53. mponent Operation 6 2 Typical Circuit Operation Non D F l 6 8 Typical Circuit Operation D F l 6 13 Diagnosis Non D F l 6 14 Cruise Diagnosis D F I 6 18 ory Non Resume Type Cruise Control 1968 1980 models General Operation The AC Cruisemaster System allows the driver to maintain a constant highway speed without having to apply continual foot pressure to the accelerator pedal Selected cruise speeds are easily maintained Speed changes may be accomplished at will and override features allow the vehicle to be accelerated slowed or stopped To engage cruise control the driver merely acceler ates to the desired cruise speed above 30 mph and then fully depresses and slowly releases the control switch button For ease of operation the control switch button is located in the end of the turn signal lever or gear shift lever figure 1 1 Figure 1 1 Non Resume Type Cruise Control Turn Signal Handle and Switch When engaged the cruise system controls throttle po sition Vehicle speed is maintained regardless of ter rain changes However extremely steep hills heavily loaded vehicles and significant changes in altitude may cause some variation in selected cruise speed J 2 1 gt amp 390915 Refer to figure 1 2 When the control switch button is pow held in the completely depressed posit
54. nit solenoid valve open and close as you make and break contact with the terminal Both valves will click twice indi cating that each respective valve is function ing properly c Functional Test Engine Operational Step 1 Prior to starting the engine disconnect the bead chain cable or rod actuator at the servo unit Disconnect the electrical connectors at the vacuum control and servo unit valves Step 2 Step 3 Start engine and let idle Install jumper wires from battery positive terminal to one terminal on both vacuum control valve and servo unit solenoid valve Ground second terminal on each valve Servo diaphragm should fully re tract indicating both solenoid valves are functional Remove battery jumper from servo solenoid the diaphragm should return to full exten sion proving that no vacuum is reaching it If it does not fully return the servo unit sol enoid valve is leaking and must be replaced Step 4 Step 5 Reinstall battery jumper wire to servo sol enoid and remove battery jumper from vac uum control valve Diaphragm should return to full extension If it does not the vacuum control valve is leaking and must be replaced d Controller Current Leakage Test at Servo Unit Solenoid Valve Connector Engine Operational Step 1 Disconnect electrical connector at servo sol enoid valve switch in position Step 2 With car running at idle check D C voltage between connector terminals
55. o measure the vol tage at both sides of the BRAKE RE LEASE SWITCH e f the voltage reading is the same the switch is closed and requires no adjustment e no voltage is measured on either side of the switch an open circuit exists between the switch and bat tery Perform repairs as necessary e f battery voltage is present on one side of the switch and not the other the switch requires adjustment 6e Reconnectthe connector at POINT A Connect a voltmeter to the hot side of POINT B with a small probe to 61 6f Depress the engagement switch half way Voltage should be present If voltage is not shown replace the en gagement switch with a known good switch and re check If no defect is found go to 6g 69 Disconnect the harness connector at the TRANSDUCER Connect a volt meter to the hot side of POINT C at the harness Depress the engage ment switch half way Battery voltage should be present If no voltage is shown repair the harness between POINT B and POINT C If no defect is found go to Step 7 If the solenoid wil not engage and voltage is present at point disconnect the connector at the TRANSDUCER and measure for continuity between point E and ground with an Ohmmeter resist ance should read 5 to 6 Ohms A lower resistance reading requires replacement of the transducer If the resistance is higher than 6 Ohms check the transducer casting to ground resistance If the ground is
56. o to Step 5 Check the brake switch circuit e Disconnect the electrical connectors at the transducer and resume solenoid valve figure 2 5 Connect a voltmeter to the side of harness connector at the RESUME SOL ENOID VALVE figure 2 6 With the igni tion the voltmeter should indicate voltage reading e Depress the brake pedal in incre ments to 14 inch The voltage reading should drop to 0 If necessary adjust the brake release switch If no defect is found proceed to Step 6 Figure 2 5 Disconnect Electrical Connectors at Transducer and Resume Solenoid Valve CYLINDERS Figure 2 6 Check Resume Solenoid Valve Connector with Voltmeter 2 3 Resume Type Cruise Control ENGAGE COAST BUTTON OFF ON RESUME SWITCH Figure 2 7 Typical Resume Engage Switch Wiring Figure 2 8 Check Resistor Wire and Transducer Solenoid Coil with an Ohmmeter 2 4 Step 6 Step 7 Check the resume solenoid valve by applying 12 volts dc to the hot side of the valve ob serving polarity The energized solenoid coil should emit an audible click and the valve should conduct vacuum If no defect is found proceed to Step 7 Check the electrical operation of the en gagement switch figure 2 7 Use the Switch Function Table or replace the engagement switch with a known good switch If no de fect is found proceed to Step 8 Switch Function Table St
57. ottle re turns to an idle position and the car s speed de creases The car will cruise at the speed of the car when the button is released The system can be disengaged four ways 1 by De pressing the brake pedal this opens the CRUISE CONTROL RELEASE SWITCH by removing the Brake Input signal to the ECM and vents the POWER UNIT vacuum to the atmosphere 2 by Moving the shift lever out of the Drive range this removes the Drive Input from the ECM 3 by turning the CRUISE CON TROL SWITCH to off 4 when the ECM sets any diagnostic code Turning the system off erases the speed in memory To again use the system it must be turned back and repeat the procedures for setting a desired speed If the system has been disengaged by any method other than turning the system off the system will resume operation when the cause of disengagement has been removed To re engage the system place the ENGAGE SWITCH in the Resume Acceleration po sition and release it The ECM receives the Resume Accel input signal and operates the CRUISE SERVO SOLENOID VALVE to accelerate the vehicle at a con trolled rate until the previous set speed is reached again If the driver wishes to advance the speed from the initial set speed keeping the switch depressed will accelerate the car at a controlled rate until the switch is released The car will not cruise at the new speed 6 13 VI Electronic Cruise Control Diagnosis
58. pplied to the servo unit solenoid valve In turn the servo unit solenoid valve regulates the vacuum supplied to the servo to initially set or reset the speed c Fully Depressed The electronic controller signals the power unit solenoid valve to vent the servo unit to atmosphere This position is used by the driver when a decrease in speed is desired The driver may fully press the button with no pressure on the accelerator pedal In this case the throttle returns to idle and the car slows When the button is released the vehicle will cruise at the new lower speed With the instrument panel switch in the AUTO position the engagement switch operates as follows a Switch in Fully Released Position Operation is the same as when the instrument panel switch is in the CRUISE position b Switch Partially Depressed Detent Position This position allows the driver to engage the system at ALL THE WAY IN a given speed resume that speed after braking and accelerate from a previously set speed After obtain Moli ing the desired speed using the accelerator pedal the RELEASE driver can partially depress the engagement switch and the electronic controller will provide a control vol tage to the servo unit solenoid valve and regulate the required vacuum to the servo unit to maintain the set speed If the driver momentarily applies the brakes and wishes to resume the previously set speed par tially depressing and releasing the engagement swi
59. rm the switch tests If Code 73 sets refer to diagnostic chart 73 If Code 73 passes then the DFI system is OK Code 60 was caused by operator error by an improperly adjusted transmis sion lever CODE 60 CRUISE CONTROL CIRCUIT TRANSMISSION NOT IN DRIVE PERFORM SWITCH TESTS CODE 73 CODE 73 PASSES SETS CHECK FOR PROPER ADJUSTMENT OF REFER TO ADL SWITCH CODE 73 REFER TO CRUISE CONTROL CIRCUIT Figure 6 13 D F I Code 60 6 19 VI Electronic Cruise Control DFI CODE 63 CRUISE CONTROL CIRCUIT e START ENGINE AND CRUISE ENABLE ON MOMENTARILY DISCONNECT ENTER OUTPUT CYCLING TESTS THE SIX PIN FUEL SERIES 9 6 PUMP WEATHER PACK e CHECK THE CRUISE CONTROL CONNECTOR AT THE REAR OF VACUUM AND POWER VALVES THE FUEL TANK ENGINE WILL TO HEAR IF THEY CYCLE CLICK STALL ON AND OFF DOES VACUUM DOES POWER VALVE VALVE CYCLE CYCLE YES DISCONNECT POWER VALVE CONNECT A TEST LIGHT BETWEEN THE HARNESS CONNECTOR PINS DISCONNECT VACUUM VALVE 2 CONNECT A TEST LIGHT BETWEEN THE HARNESS CHECK FOR CONNECTOR PINS BINDING LINKAGE CHECK FOR VACUUM HOSE LEAKS OR BLOCKAGES CHECK CHECK REPLACE CIRCUITS CIRCUIT POWER 402 OR 402 FOR VALVE 151 FOR A SHORT SOLENOID AN OPEN TO VOLTAGE LIGHT GOES ON AND OFF EVERY 3 SECS CHECK CIR CHECK REPLACE CHECK CHECK FOR FAULTY ECM CUITS 919 CIRCUIT VACUUM CIRCUIT CONNECTOR OR FAULTY ECM OR 4403 FOR 403 FOR VALVE 4402 F
60. roportion to the speed of the rotating magnet The rubber clutch controls the motion of the SLIDING VALVE figure 1 13 which changes the size of the opening in the ORIFICE When the cruise control function is engaged engine vacuum is applied to the SERVO through PORTA and PORT of the TRANSDUCER figure 1 26 Air entering through the transducer AIR FILTER is metered through the preset window openings in the orifice tube The resulting vacuum level establishes initial throttle positioning During initial engagement the orifice tube windows are about half open figure 1 14 This opening has been adjusted at the factory or by a repair station serv ice technician SLIDING VALVE ORIFICE WINDOWS CLUTCH Figure 1 13 Variable Orifice Orifice Tube and Valve Assembly VACUUM SPRING 777777777 THROTTLE ORIFICE WINDOWS HALF OPEN Figure 1 14 Initial Engagement Orifice Window Position 72 Open 1 8 po x Non Resume Type Cruise Control When vehicle speed drops the valve moves and makes the orifice tube windows smaller or completely closes the windows figure 1 15 This reduces or shuts off the amount of bleed air to the servo which increases the vacuum level in the servo Increased vacuum draws in the servo diaphragm which pulls the rod
61. s the pushbutton switch and the electronic controller will provide a control voltage to the servo unit so lenoid valve and regulate the required vacuum to maintain the set speed When a decrease in speed is desired the driver may depress and hold the button with no pressure on the accelerator pedal The elec tronic controller signals the servo unit solenoid valve to vent the servo unit to atmosphere In this case the throttle returns to idle and the car slows When the button is released the vehicle will cruise at the new lower speed c Slide Lever Actuation This switch allows the driver to resume a previously set cruise speed after braking and accelerate from a previously set speed If the driver momentarily applies the brakes and wishes to resume the previously set speed depressing and releasing the slide switch above approx 25 mph will accelerate the car at a controlled rate until the previously set speed is reached If the driver wishes to advance the speed of the car from an initial set speed actuating and hold ing the slide switch will accelerate the car at a con trolled rate until the slide switch is released The car will now cruise at the new speed Figure 6 9 Cruise Engagement Switch 1980 and Later 6 7 VI Electronic Cruise Control Typical Circuit Operation Non D F l Refer to the Non DFI schematic diagram on the fold out page figure 6 10 With the IGNITION SWITCH in Run voltage is appli
62. s with mineral spirits See figure 4 2 Recheck by blowing low pressure air into PORT A while PORT B is plugged and then into PORT while PORT is plugged In both cases air should exit out of PORT C To check flow in the other direction blow air into PORT no air should exit out of PORT B or PORT Check the 3 port valve for proper installation Notice that the arrowhead shaped portion of the 3 port check valve must always point to the intake manifold fig ure 4 2 port c 4 2 TO INTAKE MANIFOLD lt PORT A PORT Figure 4 2 3 Port Check Valve 4 2 ERM imACS ERI CAL TER Va GASOLINE LNE HAD fot T ERMIMAE gt AC diesel transducers for cruise control produced be fore 1980 72 are the non resume type Transducers produced for later models are the resume type The diesel transducer is similar in physical appear ance to the gasoline transducer To identify the units the transducer clutch housing assembly of the diesel transducer is either blue or black in color figure 5 1 Another difference is the electrical blade terminal ar rangement Starting in 1979 the HOLD and EN GAGE blade terminals were changed from a de sign to a parallel design Diesel Transducers have a Blue or Black Colored Housing CAUTION DIESEL TRANSDUCERS ARE NOT TO BE INTERCHANGED WITH GASOLINE TYPE TRAN
63. tch above approx 25 mph will accelerate the car GOTHOS D at a controlled rate until the previously set speed is pe reached If the driver wishes to advance the speed of the car from an initial set speed partially depressing and holding the engagement switch will accelerate the car at a controlled rate until the push button is released The car will now cruise at the new speed c Fully Depressed Operation is the same as when the instrument panel switch is the CRUISE position Figure 6 8 Cruise Engagement Switch 1979 1980 6 6 VI Electronic Cruise Control Cruise Engagement Switch 1980 and Later The engagement switch located within the turn signal lever has various modes of operation figure 6 9 With the instrument panel switch the posi tion the system will not operate With the instrument panel switch in the position the en gagement switch operates as follows a Switches in Fully Released Position 1 System not engaged No function of the system will occur 2 System has been previously engaged Control vol tage is being supplied to the servo unit solenoid valve from the electronic controller The servo unit solenoid valve regulates vacuum to the servo unit which main tains throttle position for desired speed b Pushbutton Depressed and Held After obtaining the desired speed by using the ac celerator pedal the driver can momentarily depres
64. tor all other mod els When controlled vacuum is applied to evacuate the servo atmospheric pressure applies a force to the diaphragm and moves the diaphragm inward pulling on the actuator to open the throttle SPEEDO FRAME ELECTRONIC CONTROLLER Figure 6 3 Vehicle Speed Sensor POWER UNIT VACUUM SOLENOID VALVE TO VACUUM SOURCE POWER UNIT VACUUM CONTROL VALVE Figure 6 4 Vacuum Control Valve and Servo Power Unit 6 3 VI Electronic Cruise Control Brake Release Switches One electrical brake release switch and one vacuum release valve are employed in the Cruise Control system figures 6 5A and 6 5B When the brake pedal is depressed the electric release switch cuts off the voltage supplied through the instru ment panel switch to the electronic controller Engagement switch operation is required to return the electronic controller to operation The vacuum release valve operates after the electric release switch disengages whenever the brake pedal is depressed This switch serves as a backup release system and opens a port that vents the servo unit to atmospheric pressure thereby allowing the throttle to return to the idle position BRAKE PEDAL MOUNTING BRACKET BRAKE PEDAL SPEEDOMETER SHAFT VACUUM RELEASE VALVE AND TORQUE CONVERTER CLUTCH RELEASE SWITCH BRAKE PEDAL STOP LAMPS AND CRUISE CONTROL RELEASE SWITCH VALVE ASSEMBLY ADJUSTMENT PROCEDURE STOP LAMPS AND 1
65. transducer RESUME VALVE Figure 3 1 shows an air pump and air management valve as installed in a typical J car Typical Air Pump and Air Management Valve Installation Under normal vacuum conditions air bleeds into the system in the direction shown by a single arrow fig ure 3 3 It flows from the transducer RESUME VALVE to the of the 3 CHECK to the 2 CHECK VALVE to the intake manifold As the AIR PUMP supplies air to the AIR MAN AGEMENT VALVE a small amount of air is diverted through the ASPIRATOR to the atmosphere Ven turi action within the ASPIRATOR develops vac uum It is this vacuum that provides the assistance needed under high load cruise conditions If manifold vacuum falls below ASPIRATOR vac uum the 2 PORT CHECK closes and the 3 PORT CHECK VALVE opens When the 3 CHECK VALVE opens a higher vacuum is available to the cruise system This provides the vacuum needed to maintain the cruise function The Double Arrows figure 3 3 show direction of air flow during aspirator assist To eliminate possible installation errors note that the check valves are arrow shaped and point in the direc tion of air flow figure 3 3 3 1 Aspirator Assisted Vacuum System System Diagnostics The cruise control function in 7 is directly re
66. umm WS mm um UD ND UR 74 TRANSDUCER TO VACUUM SOURCE tt ditryyt As peliat a ef c pot Lema CAT LE eerta a 2 Qe uet eaa ora Lose aac m vi A Mt Q gt 11 Resume Type Cruise Control General Operation The AC Cruisemaster resume system with RESUME operates somewhat similarily to the non resume type system The major difference is that with the resume feature the driver may resume a pre set speed after the system has been disengaged by braking This is done by moving a slide switch on the cruise control lever handle momentarily to the Resume position figure 2 1 Note that the Off On Resume slider switch has three positions The switch turns the cruise control system on and off It also returns cruise control operation to the last speed setting when placed in the Resume position When the slider switch is in the Off posi tion set speed memory is canceled The cruise switch button located in the end of the multifunction lever has three functions 1 engage the cruise mode 2 a coast position which allows the driver to decrease speed and 3 the normal or the fully released position NOTE Low speed switch engagement ranges from 30 to 40 mph Refer to applicable service manual or bulletins Cruise System Components Cruise system components with the exception of the resume

I. Non-Resume Type Cruise Control - 73

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