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Anti-Lock Brake System - VN,VHD w

1. 31 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Troubleshooting Diagnostic Messages Diagnostic messages are provided as text descriptions The following is a list of the possible fault condition mes or SAE J1587 J1708 fault codes MID SID and FMI A sages for the Instrument Cluster graphic display Line 3 list of these fault codes for ABS follows and the corresponding SAE J1587 J1708 code All ABS fault codes in the Instrument Cluster graphic dis Fault Description FMI s Failure play have the following for line 1 Modes Fault Description MID Data valid but high 0 Message Date valid but low 1 Brakes 198 Data erratic 2 Far Voltage shorted high 3 The following is a list of the possible faulty component messages for the Instrument Cluster graphic display Voltage shorted low 4 Line 2 and the corresponding SAE J1587 J1708 code Current low or open C 5 Fault Description SID s Subsys Current high or short C 6 tem ID s Mech syst no respons 7 ABS Snsr axle 1 L 1 Abnormal freq or PW 8 ABS Snsr axle 1 R 2 Abnormal update rate 9 ABS Snsr axle 2 L 3 Abnormal change rate 10 ABS Snsr axle 2 R 4 Failure unknown 11 ABS Snsr axle 3 L 5 i Bad device 12 ABS Snsr axle 3 R 6 7 J Out of calibration 13 ABS valve axle 1 L 7 EU Special instructions 14 ABS valve axle 1 R 8 ABS valv
2. No ECU power ABS ECU power relay R7 bad e Check power and ground at relay R7 PR2 R9 R3 coil Measure voltage from circuits 196B to OR H pins 86 to 85 of the relay holder e Try replacing relay R7 PR2 R9 R7 with a known good relay Relay R3 bad or short circuit in harness e Unplug relay R3 PR2 R9 R7 ABS light should go out If not check circuit 779 for short to ground e Check power and ground at relay R3 PR2 R9 R7 coil Measure voltage from circuits 196B to 778 pins 86 to 85 of the relay holder e Check circuit 778 from the ABS ECU for a short to ground e Try replacing relay R3 PR2 R9 R7 with a known good relay 44 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Troubleshooting Component Troubleshooting Symptom Type of Failure Check Important The following mus t be performed with the ignition ON ABS warning lamp does not illuminate at key ON ABS warning bulb burned out Perform an instrument cluster bulb test from the cluster diagnostic menu screen CLUSTER SELF TEST BULB TEST Relay R3 is bad or short circuit in har ness Try replacing relay R3 PR2 R9 R7 with a known good relay Remove relay R3 and check for battery voltage at circuit 779 pin 87A of R3 PR2 R9 R7 relay holder Should read 12V Check connections in the harness Bad ground to relay R3 Check relay R3 PR2 R9 R7 ground wire cir cuit OR F f
3. 33 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Troubleshooting Example Blink Codes Active Fault 1 8 Flashes N 1 6 Flashes Pause Pause gt e9 155 X2 Ali 155 Leis os Zug 383 Xd 1 5 s 3692 693 Su Light ON 1st Digit 2nd Digit Repeat of Blink Code 2 3 2 3 Continues until ignition is turned off Example Blink Code 2 3 Fault in ABS modulator valve right rear drive axle Stored Faults Displays all stored faults once last fault Pause Pause OS A az endi fu y 55 EXE 2699 093 stored is displayed first Light ON 1st Digit 2nd Digit 1st Digit 2nd Digit 1st Stored Fault 2nd Stored Fault 5 2 3 4 Example Blink Code 5 2 Sensor signal erratic left front steer axle 3 4 Too much sensor gap left rear drive axle System O K Blink Code 1 1 System OK Light ON Mm m 34 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Troubleshooting Example Blink Codes Continued Note After faults are cleared and vehicle is started ABS lamp will stay Faults Cleared on until vehicle is driven over 4 mph 6 km h Continues until Pause a RT uz X Pause Pause RCM ignition is 1B Sen ond Lass OO Yede e TOROS 45 2099 Steg 259 Ge turned off Light ON 8 Quick Blinks Faults Cleared System ID System ID System ID System ID 2 2 2 2 System Confi
4. Ohisawnous H noa anis ANNOYS anis ANNOYS MOO HOIHALNI H ION3 JHL NIHLIM Q31V201 annoy 7M09 3018 ANIDNA MOI HOIH3INI TEN AIR oo SI HOLSIS3Y4 SNILYNINYIL i cana axy 3HL S3NION3 OATOA aX Ixy Twv an i HOSN3S HOSN3S HLIM GaddINOA S3T10IH3A 3LON HOSN3JS HOSN3S HOSN3JS HOSN3S i uvau y HV3H 1 uv3H Y HV3H 1 1NOH3 4 L1NOH4 1 1 I 1 3ATVA i Holvinaow jHO1V1ndON IO1V 100 HOIVInQOW TOULNOO uv3u uvau 1NOyW 1NOy4 i NOLLOVEL i LHOIU 1431 1H5ld 1331 1 I I I u N I I u 1 1 RN IL E I 1 I I I I i i i i I y e v E el e El I T 1 1 I noa sav i LT i F z e EE 2 a E 18 vol vol n Mo p t asn4 asn4 LL 1 B i n SON id i SOLLSONDVIO dav y H Bay UTTVEL quy ONINHYM SOL sav ER EN dalsn1o I HOLIMS IN3WNULSNI OHLNOO NOLLOVH L I i Il ____ SYO _ i AYI34 O S3710IH3A 3WOS NO AINO 3 IXv HO4 SHOSN3S diWv1 L SOL HLIA SATOIHJA NO AINO SLN3NOdWOO 3SIHL JLON ale ONINHVA A sav HOLSIS3H ONILVNIWYSL NId 8 NHHL SSVd SISSVHO SAA ZL no3an ona Z Nid 84 NUHL SSVd ANION 9 yor NMOUG HOLO3NNOO TINNVHO 9 noa s 38M xv N3349 HOLOANNOO uvau noa v 610v 18 HOLO3NNOO NOU NOF El AHOSSdODv AVuD HOLO3NNOO avo noa E NOLINOI e xm 27 28 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Troubleshooting Troubleshooting Anti Lock Brake System Troubleshooting 1 VCADS Pro
5. 8 Relay Location in Truck Electrical Center in center of dash Troubleshooting This initiates the blink code cycle The blink code cycle consists of light flashes and pauses At the beginning of each cycle the light is on briefly then there is a 1 5 second pause followed by a 1 8 flashes which identifies the first digit of the fault Af ter another 1 5 second pause the second set of 1 6 short flashes identifies the second digit of the fault Note the blink code s e For an existing fault the ABS warning lamp will repeatedly display one code with a 4 sec ond pause in between codes until the ignition has been cycled The system will not display another existing blink code until the fault for the one displayed has been corrected and erased from the ECU e Fora stored fault the lamp will display a code for each stored fault then stop blinking Faults will be displayed one time only Turn the vehicle ignition switch OFF Refer to the Blink Code Diagnostics table to deter mine the fault information Note Perform Steps 6 through 8 only if a blink code is received that is not listed in the Blink Code Diag nostics table Verify all ABS electrical connections are tight Check for corrosion and damaged wiring Attempt to clear the fault from the ECU see Clearing Fault Codes page 37 If the fault will not clear the problem may be in the ECU itself Contact ROCKWELL WABCO for addi tional instructions
6. J 38500 60A Diagnostic cable adapter Kent Moore J 38500 1100 MPSI Wabco ABS cartridge Kent Moore J 44012 Interface Adapter ProLink 501002 Power Data Cable current version MPSI 10 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Tools VCADS Pro Tools The following hardware is used to operate VCADS Pro The tools can be ordered from Volvo Trucks North America quoting the specified part number 1 PC tool package 2 9998555 Communication interface unit 3 9812331 Extension cable 4 J 43999 6 pin Diagnostic adapter for vehicles prior to 1999 J 43939 9 pin Diagnostic adapter for vehicles built from January 1999 9998496 Pressure gauge 9998495 Air Pressure Hose 12 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Design and Function Design and Function Anti Lock Brake System 4S AM ABS with Traction Control A Air Lines B Electrical Lines 1 Wheel Speed Sensors 2 ABS Modulator Valves 3 Relay Valve 4 E Version ECU System Description The ROCKWELL WABCO Anti Lock Braking System ABS is an electronically controlled system that continu ally monitors wheel speed and controls wheel braking during extreme braking situations The ABS works in conjunction with the standard vehicle braking system A typical ABS configuration uses 4 wheel speed sensors and 4 air modulator valves This is known as a 4S 4M configuration A 6S 4M 6 sensors
7. Sensor page 16 Modulator Valve page 17 Electronic Control Unit ECU page 20 Electrical page 21 Instrumentation page 22 Traction Control System page 23 Tractor ABS Fault Detection page 24 ABS Self Tests page 26 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Design and Function Sensor The sensor is a magnetic inductor that allows current to flow through it from the ECU when the tooth wheel is passing in front of it It continuously provides wheel speed information in the form of an AC signal to the ECU whenever the ignition is ON regardless of whether or not the vehicle is in motion The sensors are installed in brackets that are bolted to the brake spider Each sensor is held in place by a spring clip The sensor is installed by pushing it all the way into the spring clip until it touches the tooth wheel The ABS is available in a 4 or 6 sensor configuration The standard 4 sensor 4 modulator ABS has a sensor on each front wheel On a 4x2 vehicle each rear wheel also has a sensor On a 6x4 vehicle with 4 spring leaf suspension with center equalizer or dogbone the for ward drive axle has sensors On a 6x4 vehicle with all other suspensions the rear drive axle has sensors e g VOAS B ride T ride RT HN HAS460 On a 6x4 vehi cle with traction control both axles have sensors The 6 sensor configuration also utilizes 4 modulator valves and has a sensor
8. fault no longer exists Clear faults as follows 1 Ignition ON 2 Remove relay R3 R9 for 3 seconds and reinsert 3 The ABS warning lamp should quickly blink on and off about 8 times then after a 4 second delay will show the blink code for the system configuration 2 blinks for 4S 4M 4 blinks for 6S 4M The 4 second delay and system blink code will repeat until the ig nition is cycled Note If the 8 quick blinks are not displayed the fault has not been cleared Repeat the procedure Relay Location in Truck Electrical Center in center and check for existing faults if the fault will not clear of dash Note After faults are cleared and vehicle is started ABS lamp will stay Bl ne Stored Faults on until vehicle is driven over 4 mph 6 km h Continues until AAA O ET EEE gt uy ignition is E KIN A EN LEN 29595 X93 X693 turned off Light ON 8 Quick Blinks Faults Cleared System ID System ID System ID System ID 2 2 2 2 System Configuration Code 2 45 4M System Remove R3 R9 Faults Not Cleared Active Faults Still Exist for3S STO E Continues until qe xx KH X ignition is turned off Light ON System ID System ID System ID System ID 2 2 2 2 Note The System ID code is 2 blinks for 4S 4M 4 blinks for 6S 4M 38 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Troubleshooting Component Troubleshooting AN DANGER Before working on a vehicle set the parkin
9. 4 modulator valves configuration is also available The ABS monitors the wheel speed at all times and helps control braking dur ing hard braking or slippery road conditions The ABS improves the vehicle s stability and control by reducing wheel lock during braking If the ABS detects a problem in the system the ABS in the affected wheel s is disabled but that wheel still has normal brakes Signals from the wheel speed sensors are received and processed by the ABS Electronic Control Unit ECU When the ECU determines that a wheel is going to a locked condition the appropriate modulator valve is acti vated and pressure to the brake chamber is reduced When the wheel speed enters the stable region again the air pressure is increased Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Design and Function Traction Control System Some vehicles are equipped with a Traction Control Sys tem ATC or ATC ATC prevents the drive wheels from spinning when starting from a standing position on a slippery surface or when accelerating The ATC utilizes the ABS ECU for control but requires an additional con trol valve to automatically apply compressed air to the spinning wheels to increase traction Fig 3 ABS Modulator Valve Cable Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU The Anti Lock Brake System ABS is an important com ponent of the foundation brake system Its purpose is to preven
10. See VCADS Pro page 30 2 Instrument cluster diagnostic display see Diagnosing Faults using the Instrument Cluster page 31 3 ROCKWELL WABCO blink codes see Diagnosing Faults using Blink Codes page 33 4 Byremoving a relay see Clearing Fault Codes by Removing R3 R9 page 38 For additional troubleshooting information see e Component Troubleshooting page 39 e Other Component Troubleshooting page 43 All codes must be in a stored or inactive state before clearing Note You must use Multiple Protocol Cartridge MPC and Meritor WABCO application card version 2 0 or higher with E version ECUs The PLC functions of E version ABS cannot be tested with the Pro Link Note Tire size range For proper ABS ATC operation with the standard ECU front and rear tire size must be within 14 of each other Exceeding this size allowance with out electronically resetting the ECU may cause the warning lamp to illuminate and the system to deactivate If the difference between front and rear tire sizes will be greater than 14 contact ROCKWELL WABCO for instructions on how to reset the ECU Calculate the tire size with the following equation t Difference REM er is 100 RPM Drive RPM tire revolutions per mile 29 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Troubleshooting VCADS Pro VCADS Pro is a Windows based software tool used to perform tests and calibrations on ECUs o
11. be ordered from the vendor specified in the tool description Please use the corresponding tool number when ordering Kent Moore 1 800 328 6657 J 42942 ABS sensor adjustment tool Kent Moore J 35123 Metri Pack hand crimp tool Kent Moore ls J 38125 Metri Pack contact removal tool Kent Moore J 34182 Deutsche universal hand crimp tool Kent Moore J 37451 Deutsche heavy duty contact re d moval tool Kent Moore E J 42189 Air line release tool Kent Moore Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Tools Fluke 87 Digital Multimeter John Fluke Mfg Corp J 44399 Air System Tester uu 4 J 44775 Valve Assembly Fixture J 43143 NA J 43143 Tie Strap Tensioner J 44773 Airline Release Tool J 44769 Wheel Speed Sensor Extractor J 42883 Sensor pin out cable Kent Moore Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU J 44966 Wheel Speed Sensor Remover for Heavy Duty Steer Axle and Alu minum Hub Tools Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Tools Special Equipment The following special equipment may be required for troubleshooting the Anti Lock Brake System and can be ordered from the vendor specified in the equipment descrip tion J 38500 2 Power Data Cable earlier version Kent Moore 1 108004 Pro Link 9000 with cartridge 2 208040 MPC Cartridge 3 808014 Wabco Application Card J 38500 60A
12. on each front wheel and on each drive axle wheel Note On Heavy Duty Steer Axles and steer axles with Aluminum Hubs some sensors are installed without the use of a bracket bolted to the Brake Spider 16 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Design and Function Modulator Valve The ABS modulator valve is an air solenoid valve It has two solenoid coils One of the coils is energized to iso late the brake chamber from the brake system supply and vent the brake pressure from the brake chamber The other coil is energized to isolate the brake chamber from the brake system supply and hold the pressure that is in the brake chamber During normal braking compressed air for braking flows freely through the modulator valves to the brake cham bers When ABS function is required the modulator valve for the affected wheel is energized on and off in order to quickly but incrementally reduce the braking air pres sure to the point where the wheel begins to spin freely The modulator valves are located in the air supply path between the relay valve or quick release valve and the brake chambers They are physically attached to the frame rail near the front wheels which they supply and on the crossmember nearest the rear wheels Front ABS Valve Package Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU R 14 Relay Valve The relay valve in an air brake system functions as a re lay
13. station to speed up the application and release of the brakes The valve is normally mounted at the rear of the vehicle near the chambers it serves The valve operates as a remote controlled brake valve that delivers or re leases air to the chambers in response to the control air delivered to it from the foot brake valve The R 14 relay valve is designed for either reservoir or frame mounting The R 14 incorporates a quick release and anti compounding feature located above the hori zontal service port The R 14 anti compound feature allows it to be conveniently used as either a service or spring brake relay valve An exhaust cover is installed that protects the 3 mm 1 8 in balance port when the R 14 anti compound feature is not in use Operation Application Air pressure delivered to the service port enters the small cavity above the piston and moves the piston down The exhaust seat moves down with the piston and seats on the inner or exhaust portion of the inlet exhaust valve sealing off the exhaust passage At the same time the outer or inlet portion of the inlet exhaust valve moves off its seat permitting air supply flow from the reservoir past the open inlet valve and into the brake chambers Balance The air pressure being delivered by the open inlet valve also is effective on the bottom area of the relay piston When air pressure beneath the piston equals the service air pressure above the piston lifts slightly and the inl
14. the frame rail 4 Remove the wheel speed sensor har ness hold down from the top kingpin cap 5 Remove the wheel speed sensor from the housing in the spindle using tool J 44966 J 44966 6 Remove the wheel speed sensor har ness from the vehicle 7 Install the removed wheel speed sen sor hold down to the replacement wheel speed sensor harness and se cure Service Procedures 8 Replace the removed tie straps to se cure the replacement wheel speed sensor harness 5931 03 02 01 ABS ECU Replacement Before beginning this procedure read the General Work Practices section General Work Practices page 49 for further procedural information 1 AN DANGER Before working on a vehicle set the parking brakes place the transmission in neutral and block the wheels Failure to do so can result in unexpected vehicle movement and can cause serious personal in jury or death Park the vehicle on a level surface with the transmission in neutral and the front wheels chocked Disconnect the engine ECU ground wire if the vehicle is equipped with one Remove the battery box cover and dis connect the negative battery cables 3 Disconnect the three ABS ECU con nectors from the ECU 4 Cut the two tie straps securing the channeled wiring harnesses to the brackets supported by the ECU studs and nuts 57 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU 5 Remove the tw
15. 4 753 RF Modulator Hold 5 750 RF Sensor Signal Front Black ECU Connector 6 751 RF Sensor Return 7 730 LF Sensor Signal 8 731 LF Sensor Return 9 754 RF Modulator Common 10 732 LF Modulator Exhaust 11 734 LF Modulator Common 1 12 Not Used Rear Green ECU Connector Pin Circuit No Description 1 737 LR Sensor Signal 2 738 LR Sensor Return 3 757 RR Sensor Signal 4 758 RR Sensor Return 5 780 Traction Control Solenoid Source 6 781 Traction Control Solenoid Ground 7 759 RR Modulator Exhaust 8 761 RR Modulator Common 9 760 RR Modulator Hold 10 739 LR Modulator Exhaust 11 741 LR Modulator Common 12 740 LR Modulator Hold 6 Channel Brown ECU Connector Pin Circuit No Description 3 735 LR3 Sensor Signal 4 736 LR3 Sensor Return 5 755 RR3 Sensor Signal 6 756 RR3 Sensor Return 1 2 Not Used 7 12 Used for 6S 4M only 59 60 Feedback One of our objectives is that workshop personnel should have access to correct and appropriate service manuals where it concerns fault tracing repairs and maintenance of Volvo trucks In order to maintain the high standards of our literature your opinions and experience when using this manual would be greatly appreciated If you have any comments or suggestions make a copy of this page write down your comments and send them to u
16. AS lamp off 1 gt 05 l l l sec Single Trailer to Multiples message ON ON ON ON ON ON ON ON ON lamp on US CARLA ERU DU ME M lamp off are sec ABS lamp is on and stays on when a new trailer with new fault is added ABS fault was in exis tence before the new trailer was added The ignition was was not turned off before the trailer was added and the new trailer has an ABS fault Note ON Turn ON message to Trailer ABS lamp OFF Turn OFF message to Trailer ABS lamp 48 Removing a trailer with a fault causes the ABS lamp to turn off Repair a trailer with a fault as soon as possible and before returning to use Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Service Procedures Service Procedures General Work Practices Some older original equipment brake linings contain asbestos fibers a cancer and lung disease hazard which could result in serious illness or death Some brake linings contain non asbestos fibers the long term effects of which are unknown Caution should be exercised in handling non asbestos materials Most recently manufactured brake linings no longer con tain asbestos fibers In place of asbestos these linings contain a variety of ingredients including glass fibers mineral wool aramid fibers ceramic fibers and carbon fibers At present OSHA does not specifically regulate these non asbestos fibers except as maintenance dus
17. Service Manual Trucks Group 593 502 Anti Lock Brake System ABS MERITOR WABCO with E Version ECU VN VHD mE Emm rm PV776 TSP154520 VOLVO Foreword The descriptions and service procedures contained in this manual are based on de signs and methods studies carried out up to June 2001 The products are under continuous development Vehicles and components produced after the above date may therefore have different specifications and repair methods When this is believed to have a significant bearing on this manual supplementary ser vice bulletins will be issued to cover the changes The new edition of this manual will update the changes In service procedures where the title incorporates an operation number this is a refer ence to an S R T Standard Repair Time Service procedures which do not include an operation number in the title are for gen eral information and no reference is made to an S R T The following levels of observations cautions and warnings are used in this Service Documentation Note Indicates a procedure practice or condition that must be followed in order to have the vehicle or component function in the manner intended Caution Indicates an unsafe practice where damage to the product could occur Warning Indicates an unsafe practice where personal injury or severe damage to the product could occur Danger Indicates an unsafe practice where serious personal injury or death could o
18. action on soft surfaces like snow slush or mud by slightly increas ing the allowable wheel spin The ATC will resume normal operation when the ATC Switch is again pressed and the ATC lamp goes out or when the ignition is turned OFF ATC Switch Design and Function 23 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Tractor ABS Fault Detection During operation the ABS ECU continuously monitors the system for faulty conditions If the ABS detects that a fault has occurred as determined by the absence of cor rect signal from one of the ABS components the system illuminates the Tractor ABS warning lamp This lamp will stay on until the system has been repaired and the fault has been cleared from the ECU s memory When a fault is detected by the system it deactivates the anti lock braking function in the wheel that has the fault Normal braking ability is maintained in the wheel that has the fault however The ROCKWELL WABCO ABS ECU has the ability to store the details of faults that it detects within its own memory so that the technician can easily locate the problem The faults are placed into two categories exist ing and stored Note the instrument cluster graphic display shows these two categories as active and inac tive Existing or active faults are those present in the System such as a short circuited data link Stored or in active faults are faults which have been repaired or intermitten
19. ailer ABS Fault Detection Starting in March 2001 Federal Regulations required that each new vehicle have an in cab warning lamp that notify the operator of any faults with the Trailers ABS System Note If the vehicle is not equipped with a J560 connec tor or cable 7 way trailer connector either on the back of the cab or at the end of the frame then the vehicle is not considered Towing equipped According to Federal Regulations if the vehicle is not Towing equipped then it is not subject to the Trailer ABS Warning Lamp re quirements Control of the Trailer ABS Warning Lamp is performed by the Tractor ABS ECU The ECU works off of signals it receives from the ABS ECU s on the trailer s These signals exist in a Power Line Carrier PLC communica tion system The Trailer ABS ECU sends a message to the Tractor ABS ECU every 1 2 second relaying informa tion concerning any warnings and turning on or shutting off the warning lamp An example of a fault code for the Trailer ABS is if the Trailer ABS Warning Lamp stays on and no trailer is con nected If this occurs then there is a problem in the lamp circuit or Trailer ABS ECU Another fault code occurs if the Trailer ABS Warning Lamp remains on when a PLC compatible trailer is connected To remedy this fault dis connect the trailer cable and wait a minimum of 15 seconds before reconnecting If the lamp goes out upon reconnection then the fault is in the Trailer ABS System If th
20. al and block the wheels Failure to do so can result in unexpected vehicle movement and can cause serious personal in jury or death The graphic display of the instrument cluster can be used to display diagnostic messages from the ABS The system uses the SAE J1587 1708 data link and is in stalled in vehicles with electronically controlled engines Fault codes cannot be cleared using the instrument clus ter graphic display To see diagnostic messages 1 Stop the engine 2 Turn the ignition ON 3 Press the MODE button on the vehicle dash until the Diagnostics Menu is displayed Use the Up and Down buttons to display DIAGNOSTIC MESSAGES 4 Press the SET button to have the datalink retrieve data 5 Press the DOWN button until the brake screen is displayed The Set button can be pressed to toggle the display between the text description and the re ceived data If the display shows UNKNOWN in any line press the Set button to display the MID PID or SID and FMI a If the condition that caused the currently dis played fault still exists the cluster will display ACTIVE b If the condition that caused the currently dis played fault is no longer occurring the cluster will display INACTIVE c The number of times a fault has occurred will be displayed when available In some cases a short message may also be displayed 6 Record all codes displayed 7 To display the next stored fault press the Down but ton
21. amp does not come on within three sec onds of ignition No Bulb Check trailer added after initial power up system OK There was no trailer PLC message for at least three seconds fol lowing ignition ON Note ON Turn ON message to Trailer ABS lamp OFF z Turn OFF message to Trailer ABS lamp 46 Removing a trailer with a fault causes the ABS lamp to turn off Repair a trailer with a fault as soon as possible and before returning to use Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Troubleshooting Table B Dash mounted Trailer ABS Indicator Lamp Operation Bulb Check Information for Ser vice Technicians Status of Trailer ABS Signal from trailer to tractor ECU Lamp on Vehicle Dash Explanation Action Single or Multiple Trailers Trailer ABS lamp does Not using the PLC Use lamp on 9 P not come on within system no trailer con side of trailer ida three seconds of igni nected or trailer not to identify tion equipped with PLC or fault Make lampan fault in PLC system necessary lamp off 1 Sen 1 1___ repairs sec Single Trailer Trailer ABS lamp comes Trailer ABS fault s oc on curred during operation message OFF OFF OFF ON ON ON ON and still exists lamp on an lamp off __ 9 3 l I l sec Multiple Trailers Dollies message OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF ON ON ON ON lamp on ass aia lamp off __ 9 l l l sec Trailer ABS lamp comes Trailer ABS fau
22. ap plies to Trailer ABS only The lamp is controlled by a signal to the tractor ECU sent over the power line PLC function When a trailer ABS fault is detected an ON message is sent when no fault is detected the ECU re ceives an OFF message Table A illustrates trailer ABS lamp operation at power up or ignition on Table B de picts lamp responses that occur during operation Lamp Troubleshooting turn ON and OFF messages do not turn the lamp ON or OFF instantly The delay between the receipt of the mes sage and the lamp response time is intentional It prevents erratic lamp activity NOTE For doubles or triples the lamp does not distinguish between trailers A System fault in any of the trailers will activate the trailer ABS indicator lamp Table A Dash mounted Trailer ABS Indicator Lamp Operation Bulb Check Information for Drivers Signal from trailer to tractor ECU Status of Trailer ABS Lamp on vehicle dash Explanation Single or Multiple Trailers message OFF OFF OFF OFF OFF OFF OFF lamp on 0 5 sec lamp off __ Trailer ABS lamp comes on at ignition OFF message is onds of ignition Trailer ABS Bulb Check performed and Trailer ABS system is OK In theis case the lamp is ON for a Bulb Check only detected within three sec lamp goes out Single or Multiple Trailers message No ON or OFF messages lamp on OFFOFF lamp off AS 1 po sec ign on t 3 sec Trailer ABS l
23. aust left front axle se 11 to 10 Wiring between ECU and valve damaged ABS inlet right front axle 9to 4 ABS exhaust right front axle 9 to 3 4 0 to 8 0 Q ABS inlet left rear axle Rear green har 11 to 12 Ground lead to valve dis ness connector connected ABS exhaust left rear axle 11 to 10 ABS inlet right rear axle 8 to 9 Solenoid valve shorted ABS exhaust right rear axle 8 to 7 Traction Control valve 5 to 6 8 0 to 14 0 Q 40 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Sensors To check the resistance of a sensor perform the follow ing Verify that the vehicle ignition is OFF Disconnect the cable to the sensors at the ECU connector for front or rear sensors as appropriate Use the Sensor Pin out Cable Tool J 42883 and the Digital Multimeter Fluke 87 to check the Wheel Speed Sensor Coil Resistance Ground Resistance and Output Voltage on Rockwell Wabco ABS Brakes Measure the resistance across terminals listed on the table below Acceptable reading is between 700 and 3000 ohms SQ 9 Troubleshooting Note See tion page 59 for connector terminal loca If resistance in Step 3 was not within tolerance for the sensor perform Steps 5 through 7 Otherwise go to Step 8 Disconnect the connector for the sensor Measure the resistance across terminals 1 and 2 If resistance value is not within tolerance shown in the table the sensor must be replaced If the resis
24. bleshooting ABS Warning Lamp Trailer An amber ABS warning lamp is provided in the instru ment cluster Its function is to notify the operator that the ABS system has detected an unusual condition or fault in the system The lamp will illuminate under the follow ing conditions e To notify operator of a fault in one or more towed 22 Design and Function GIAGNOSTIC MESSAGES trailers e When the ignition switch is turned ON the lamp comes ON momentarily for a bulb check then goes out After servicing the ABS the lamp will stay ON until the vehicle speed reaches approximately 11 km h 7 mph then the lamp goes out ATC Lamp There is an amber ATC warning lamp on the instrument cluster The lamp has the following function e f the ATC switch is off in Mud Snow mode the ATC lamp will blink continuously to remind the driver that ATC is in Mud Snow mode The Mud Snow function increases available traction on soft surfaces like snow slush or mud by slightly increasing the al lowable wheel spin Diagnostic Display The graphic display is on the left side of the instrument cluster It can be used to display diagnostic messages from the ABS The system uses the SAE J1587 J1708 data link Refer to Anti Lock Brake System Troubleshooting page 29 for information on how to trou bleshoot ABS problems Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Traction Control System The ABS on a
25. c cur Volvo Trucks North America Inc Greensboro NC USA Order number PV776 TSP154520 2001 Volvo Trucks North America Inc Greensboro NC USA All rights reserved No part of this publication may be reproduced stored in retrieval system or transmitted in any forms by any means electronic me chanical photocopying recording or otherwise without the prior written permission of Volvo Trucks North America Inc Contents A AET A Kad AA AR REL a ELA 3 Anti Lock Brake System with the E Version ECU 3 Specifications aivnionaracaa arar 5 Electronic Control Unii sa 5 Dpor dece eres y BIER MOLES nee 7 Special Equipment ero usd 10 Design and Function eeen 13 Anti Lock Brake System nassen 13 System Describe cias 13 o cac ad re O FER E 15 DEBBIE cisco d e LED VER E EE S 16 Modulator VANE een 17 H 14 Relay Yale anne 18 Electronic Control Unit ECU ea 20 EIERN na iia 21 BTU ALIGN sp online iii 22 Traction Control System esses 23 Tractor ABS Fault Detection ee 24 Trailer ABS Fault Detection 25 ABS OIR A e T 26 Troubleshooting sesssssssseses 29 Anti Lock Brake System Troubleshooting 29 poer Rc lia 30 MPSI Pro Link 9000 with MPC Cartridge and Application SAN Mec m aa 30 Diagnosing Faults using the Instrument Cluster 31 Diagnosing Faults using Blink Codes 33 Clearing Fa
26. cket lo cated under the left side of the dash Turn the vehicle ignition ON Important Record all fault codes on the work order before they are cleared They cannot be retrieved after clearing Follow the Pro Link menus to select stored faults Existing faults cannot be cleared only stored faults TRACTOR ABS MENU SELECTIONS 1 STORED FAULTS Press the FUNC key To clear all stored faults use the and keys to place brackets around the Y in the last line of the display then press ENTER Troubleshooting Note For information on the proper use of VCADS Pro refer to the VCADS Pro User s Manual in group 03 6 CLEAR ALL STORED FAULT S CLEAR Y N When the faults have been cleared the Pro Link screen displays the following STORED FAULT S CLEARED ENTER TO CONTINUE 37 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Troubleshooting Clearing Fault Codes by Removing R3 R9 If a Pro Link is not available fault codes may be cleared 4 lgnition OFF as follows 5 Check faults to verify that there are no faults re Note R3 is the Power Relay and R9 acts as the Warn maining ing Lamp Relay Note An existing or active fault cannot be cleared until it has been repaired Clear each fault from the ECU after it has been recorded on the work order and repaired Faults are cleared when the ECU is powered up and the
27. e Note It is not necessary to remove the wheel or drum to adjust sensors using this method J 42942 Potential sensor damage DO NOT use a hammer to drive the sensor into position Hammering the sensor could cause the sensor to be inoperative Press the sensor toward the wheel hub until the sensor contacts the tooth wheel 3 Remove the ABS Sensor Adjustment Tool J 42942 Sensor will self adjust after wheel rotation J 42942 4 Verify proper sensor adjustment as specified in Sensor Adjustment Check page 42 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU 5635 03 02 01 ABS Modulator Valve Replace ment Before beginning this procedure read the General Work Practices section General Work Practices page 49 for further procedural information AN DANGER Before working on a vehicle set the parking brakes place the transmission in neutral and block the wheels Failure to do so can result in unexpected vehicle movement and can cause serious personal in jury or death Park the vehicle on a level surface with the transmission in neutral and the front wheels chocked 2 Remove all tie straps supporting the ABS modulator valve supply airline coming from the brake chamber Service Procedures Before beginning any service work on any part of the air system be certain that the air pressure has been released Failure to do so may cause a component to violently separate whic
28. e axle 2 L 9 ABS valve axle 2 R 10 ABS valve axle 3 L 11 ABS valve axle 3 R 12 ABS rtrdr ctrl relay 13 ABS relay diagonal 1 14 ABS relay diagonal 2 15 ABS dif 1 ASR valve 18 ABS dif 2 ASR valve 19 32 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Diagnosing Faults using Blink Codes AN DANGER Before working on a vehicle set the parking brakes place the transmission in neutral and block the wheels Failure to do so can result in unexpected vehicle movement and can cause serious personal in jury or death If a Pro Link tool is not available for troubleshooting 3 ROCKWELL WABCO blink codes may be used The ABS ECU has the ability to produce a series of light flashes called blink codes to display fault codes The ABS warning lamp on the instrument cluster is used to display blink codes When the diagnostic function is activated by removing and reinstalling relay R3 R9 any existing faults will be displayed If more than one fault is current the first fault must be repaired before another existing fault can be displayed After repairing an existing fault cycle the key switch and remove and reinstall the relay to request the next existing fault After all existing faults have been repaired they will be come stored faults and can be cleared from the ECU s memory To display blink codes 1 Turn the vehicle ignition ON 4 2 Remove relay R3 for 1 second and reinstall 3 6 7
29. e lamp stays on then the error is in the Tractor ECU Note The Tractor ABS ECU does not store fault codes from the Trailer ABS System Design and Function 25 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU ABS Self Tests The ROCKWELL WABCO ABS has a variety of self monitoring features When the ignition is turned ON the ABS warning lamp in the instrument cluster illuminates to tell the operator that the system is powered and that it is conducting self tests There are two tests performed by the system at this point The first test cycles the modulator valves to ensure the circuits and valves are functional This is an audible test The valves cycle in the following order 1 Right front 2 Leftrear 3 Left front 4 Right rear One additional self test is performed by the ABS This test occurs once the vehicle begins moving As the vehi cle starts to speed up from a standstill the ABS monitors the output from each of the wheel speed sen sors and verifies that they are reading correctly and within the correct range compared with the other wheels If the test is satisfactory the ABS warning goes out when the vehicle speed reaches approximately 6 km h 4 mph If the test is not satisfactory the warning lamp will remain illuminated 26 Design and Function Design and Function Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU
30. et spring returns the inlet valve to its seat The exhaust re mains closed as the service line pressure balances the delivery pressure As delivered air pressure is changed the valve reacts instantly to the change holding the appli cation at that level Exhaust or release When air pressure is released from the service port and air pressure in the cavity above the relay piston is ex hausted air pressure beneath the piston lifts the relay piston and the exhaust seat moves away from the ex haust valve opening the exhaust passage With the exhaust passage open the air pressure in the brake chambers is then permitted to exhaust through the ex haust port releasing the brakes 18 Design and Function Fig 4 R 14 Relay valve Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Anti compounding Simultaneous service and park application When the R 14 Relay valve is used to control the spring brake chambers use the anti compound feature With the anti compound feature of the R 14 connected a ser vice application made while the vehicle is parked is countered by a release of the parking brakes To use this feature the exhaust cover of the quick release portion of the R 14 is removed and a line is connected to the deliv ery of the service brake valve or brake application is made air from the service brake valve enters the ex haust port of the quick release of the R 14 and moves the diaphragm blocking the serv
31. for circuit information Relay Number Relay Function R3 Power Relay R9 Warning Lamp Relay PR2 Alternate Power Relay R7 Alternate Warning Lamp Relay Troubleshooting 43 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Troubleshooting The following table provides additional possible faults within the ABS not previously covered within the Troubleshooting section Component Troubleshooting Symptom Type of Failure Check Important The following mus t be performed with the ignition ON ABS light stays illuminated Diagnostic faults present Use Pro link or cluster diagnostic menu to check for stored fault codes Refer to previous troubleshooting information No ECU power Fuse blown e Check 5A 30A fuse fuse 10 in electrical center e Check 40A maxi fuse in electrical center e Check the two 10A in line fuses on the ABS ECU crossmember No ECU power Open or short circuit in cab or chassis harness power ground circuits e Check voltage at the gray ABS ECU Cab connector terminals 1 to 11 and 2 to 12 Should read battery voltage with the ignition switch ON Note terminals 1 777A 8 2 777B are power terminals 11 ABS A amp 12 ABS B are ground e Check ECU and Cab connections for cor rosion or loose terminals e Check relay R7 PR2 R9 R3 ground wire circuit OR H for continuity to the ground bus bar in the electrical center
32. g brakes place the transmission in neutral and block the wheels Failure to do so can result in unexpected vehicle movement and can cause serious personal in jury or death If diagnostics indicate that there is a problem with the ABS the following component tests may be used to determine whether the problem is in the component or the wiring Prior to performing any component tests make a visual in spection of the cables connectors and valves for loose connections corrosion and breakage The ABS modulator valves and TCS valves can be checked by measuring the resistance of the coils This measure ment can be made at the valve or at the ECU connector ABS Modulator Valve 2 To check resistance perform the following Turn on the ignition 3 Wait for the ABS indicator lamp to come on k NS geb o DR 4 Listen to the valves cycle consecutively as follows 4 Channel Valve Cycle Order 1 2 3 4 6 Channel Valve Cycle Order 1 2 3 4 5 6 2 Disconnect the cable to the modulator valves at the ECU connector for front or rear components as ap propriate Traction Control Valve 3 Measure the resistance across terminals listed on y f To check resistance perform the following the table below Acceptable reading is between 4 0 and 8 0 0 1 Verify that the vehicle ignition is OFF Note See page 59 for connector terminal loca 2 Disconnect the cable to the Traction Control valves tion at the ECU connector for rear com
33. guration Code 2 4S 4M System Faults Not Cleared Active Faults Still Exist Continues until ignition is turned off Light ON System ID System ID System ID System ID 2 2 2 2 35 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Blink Code Diagnostics Chart Rockwell WABCO Blink Codes First digit Second digit Specific location of fault 1 No faults 1 No faults 2 ABS modulator valve 1 Right front steer axle 3 Too much sensor gap 2 Left front steer axle 4 Sensor short or open 3 Right forward rear tandem drive axle 5 Sensor signal erratic 4 Left forward rear tandem drive axle 6 Tooth wheel 5 Right rear rear tandem drive axle 6 Left rear rear tandem drive axle 1 J1939 data link 2 ATC valve lcd 3 Retarder relay third brake 4 ABS warning lamp 5 ATC configuration 6 ATC prop dif lock stop valve 1 Low power supply 2 High power supply 8 ABS ECU 3 Internal fault 4 System configuration error 5 Ground 36 Troubleshooting Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Clearing Fault Codes Fault codes may be cleared with the Pro Link and ROCK WELL WABCO ABS cartridge or by removing relay R3 Clearing Fault Codes with the Pro Link Note Existing faults cannot be cleared until they have been repaired Clear faults from the ECU after the faults have been recorded on the work order and repaired 1 Connect the Pro link to the diagnostic so
34. h can result in serious per sonal injury Using the Airline release tool J 44773 disconnect the relay valve supply airline on the top of the modu lator valve J 44773 4 Using the Airline release tool J 44773 disconnect the modulator valve supply airline on the brake chamber J 44773 5 Disconnect the ABS modulator valve connector 6 Disconnect the supply line from the ABS Modulator Valve coming from the brake chamber 7 Remove the two mounting bolts from the ABS modulator valve 8 Using a wrench remove the two fit tings from the ABS modulator valve J 44775 9 Using a wrench install the two fittings into the replacement ABS modulator valve with the correct pipe sealant J 44775 10 Install the replacement ABS modulator valve onto the proper mounting bracket 11 Connect the supply air line into the ABS Modulator Valve coming from brake chamber 51 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Service Procedures 12 Connect the ABS modulator valve con nector 13 Connect the ABS modulator valve sup ply airline at the brake chamber and the relay valve supply airline on top of the ABS modulator valve 14 Replace the removed tie straps to sup port airlines and various harnesses 52 5631 03 02 25 ABS ATC Valve Replacement Before beginning this procedure read the General Work Practices section General Work Practices page 49 for further p
35. ice port Air then pro ceeds into the cavity above the relay piston The piston closes the exhaust and opens the inlet to deliver air to the spring brake cavity as described in R 14 Relay Valve page 18 Maintenance Every 160 000 km 100 000 miles 12 months or 3600 operating hours check the valve function using the pro cedure found in R 14 Relay Valve page 18 If the R 14 does not function properly replace it with a new or re manufactured valve Design and Function Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Electronic Control Unit ECU The ABS ECU controls the ABS ATC system It receives wheel speed information from the sensors and sends signals to the ABS modulator valves It is powered from the ignition bus via the ABS ECU power relay R7 for VN Power Relay PR3 for the VHD and two in line fuses mounted on the crossmember close to the ABS ECU The microprocessors in the ECU compare the speed of each wheel to the speed of the other wheels to deter mine if any one wheel is spinning This comparison is performed many times every second If any wheel is de termined to be locked not spinning or spinning very slowly in relation to the other wheels while the other wheels are spinning the ABS sends signals to the mod ulator valve for the locked wheel to reduce its braking force until it starts to spin again This series of events occurs many times each second giving the modulator valve the ap
36. ing from the Backing Plate Bracket 7 Remove the wheel speed sensor from the vehicle 8 Install the replacement wheel speed sensor in the bracket 9 Route the replacement wheel speed sensor harness through the backing plate and the framerail 10 Install the wheel speed sensor bracket 11 Connect the wheel speed sensor se cure the two removed tie downs and replace all the removed tie straps 12 Install the brake drum 13 Reinstall the removed tire and wheel and adjust the brakes 14 Insuring that the jack is in a safe loca tion lift the vehicle and remove the jackstand Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU 5939 03 02 03 Wheel Speed Sensor Replace ment Heavy Duty Axle and or Aluminum Hub Before beginning this procedure read the General Work Practices section General Work Practices page 49 for further procedural information 1 AN DANGER Before working on a vehicle set the parking brakes place the transmission in neutral and block the wheels Failure to do so can result in unexpected vehicle movement and can cause serious personal in jury or death Park the vehicle on a level surface with the transmission in neutral and the front wheels chocked 2 Cut and remove the six tie straps securing the wheel speed sensor har ness to the air brake chamber and inside the frame rail 3 Disconnect the wheel speed sensor from the chassis harness in side
37. lows brakes to be automatically applied to Tooth Wheel The tooth wheel is an alloy ring that resembles a gear It usually has 100 teeth cut into its surface The purpose of the teeth are to cause a pulsating current flow in the sensor circuit As the high side of each tooth passes near the sensor it causes a small current to flow in the sensor When the area between two teeth is in front of the sensor the current flow stops As the tooth wheel rotates the starting and stopping of the current flow is seen by the ECU as pulses The greater the speed of the tooth wheel past the sensor the more pulses are registered per second which is a direct indication of wheel speed The tooth wheel is manufactured either as a ring that is pressed onto the wheel hub or is machined as an inte gral part of the hub itself Design and Function the spinning wheels The ROCKWELL WABCO ABS System consists of the following components Tooth Wheel 4 or 6 Magnetic Sensor 4 or 6 Sensor Brackets and Locks 4 or 6 Modulator Valve 4 One of the following Electronic Control Units ECUs ECU 4S 4M ABS Only ECU 4S 4M ABS with ATC ECU 6S 4M ABS with ATC Fuses and Relays Tractor ABS Warning Lamp Trailer ABS Warning Lamp ATC Indicator Lamp Connectors ATC Switch if ATC is installed ATC Valve if ATC is installed For design and function information about specific ABS components see the following Tooth Wheel page 15
38. lt oc None Single Trailer message ON ON OFF OFF OFF OFF OFF OFF lamp on Z7 lamp off er 40014 Lives 25 sec Muttiple Trailers Dollies OFF OFF OFF OFF OFF OFF OFF ON ON OFF OFF OFF OFF OFF OFF lamp on 2 _ lamp off 95 re I Lives sec message on but goes out 2 5 seconds after fault is detected curred during operation and the fault was cor rected 47 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Troubleshooting Status of Trailer ABS Signal from trailer to tractor ECU Lamp on Vehicle Dash Explanation Action Single Trailer ABS lamp is off comes ABS fault existed then Use lamp on on then goes off 10 signal was lost because side of trailer message seconds after the loss trailer disconnected or to identify Bee A S balls of messages PLC fault fault Make x necessary lamp off Ter d 1 PO repairs Muttiple Trailers Dollies OFF OFF OFF OFF OFF OFF OFF ON ON lamp on DLL lamp off ar 01 Lives sec message ABS fault existed then trailer with fault Isot sig nal because trailer was disconnected or PLC fault Single Trailer to Multiples ABS lamp is on and stays on when a new trailer with no new fault is added There was a fault in ex istence before the new trailer was added and the ignition was not turned off before the trailer was added message OFF OFF OFF ON ON ON ON ON ON lamp on eae qM FE
39. lve Pull on the air line to be sure that it is locked into the fitting 3 Install the valve to the mounting bracket using the two mounting bolts Torque the bolts to 24 Nm 18 ft Ib Service Procedures 24 Nm 18 ft Ib Traction valve mounted on LH frame rail at rear crossmember Connect the supply and delivery lines to the valve Pull on the air lines to be sure that they are locked into the fit tings 5 Connect the valve electrical connector and tighten the fastening ring 6 Build air pressure in the systems to operating pressure approx 827 kPa 120 psi Check for leaks and opera tion of the traction valve Operation of the valve can be checked with the Pro link tool J 38500 1 and ROCKWELL WABCO cartridge J 38500 404 Refer to Component Tests in the cartridge manual J 38500 1 J 38500 404 53 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU 5635 03 02 04 ABS Relay Valve Replacement Before beginning this procedure read the General Work Practices section General Work Practices page 49 for further procedural information AN DANGER Before working on a vehicle set the parking brakes place the transmission in neutral and block the wheels Failure to do so can result in unexpected vehicle movement and can cause serious personal in jury or death 1 Park the vehicle on a level surface with the transmission in neutral and the front wheels chocked Bef
40. n lift the vehicle and remove the jackstand 55 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU 5939 03 02 01 Wheel Speed Sensor Replace ment Steer Axle Before beginning this procedure read the General Work Practices section General Work Practices page 49 for further procedural information 1 AN DANGER Before working on a vehicle set the parking brakes place the transmission in neutral and block the wheels Failure to do so can result in unexpected vehicle movement and can cause serious personal in jury or death Park the vehicle on a level surface with the transmission in neutral and the front wheels chocked AN DANGER Do not work under a vehicle supported only by jacks Jacks can slip out from under the truck or fall over causing personal injury or death Always use jack stands under the truck Lift and stabilize the portion of the ve hicle to be worked on with the proper jack and jackstand 3 Remove the tire and wheel from the side to be replaced 56 Service Procedures 4 Back the brakes off on this side by us ing a small screwdriver to pry out the spring loaded pawl while releasing the brakes and then remove the brake drum 5 Remove the two wheel speed sensor harness tie downs on the spindle it self Then remove all of the securing tie straps and disconnect the sensor harness from inside the framerail 6 Remove the wheel speed sensor hous
41. n the vehicle A PC tool with VCADS Pro software is connected to the vehicle s diagnostic connector using adapters and a communication interface unit VCADS Pro Test and Calibration applications makes it possible to test and to calibrate the ECUs The applica tions consist of standard graphical interfaces displaying graph presentations and continuous reading of parame ters The Test and Calibration applications are organized according to function group Wabco ABS units installed on Volvo VN and VHD trucks are tested using the VCADS Pro tool This tool conducts troubleshooting and diagnostics for the ABS unit Note For further information on VCADS Pro refer to the VCADS Pro User s Manual in group 03 MPSI Pro Link 9000 with MPC Cartridge and Application Card The MPSI Pro Link 9000 is a hand held electronic diag nostic instrument When used with the MPC cartridge and Wabco ABS application card or with the Wabco ABS cartridge the Pro Link tool provides easy diagnosis of faults within the ABS including e afaulty input e a faulty command or e a faulty reaction to a command In addition the Pro Link 9000 provides the ability to run a series of component tests on the ABS ATC system 30 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Troubleshooting Diagnosing Faults using the Instrument Cluster AN DANGER Before working on a vehicle set the parking brakes place the transmission in neutr
42. ng on a vehicle set the parking brakes place the transmission in neutral and block the wheels Failure to do so can result in unexpected vehicle movement and can cause serious personal in jury or death Park the vehicle on a level surface with the transmission in neutral and the front wheels chocked AN DANGER Do not work under a vehicle supported only by jacks Jacks can slip out from under the truck or fall over causing personal injury or death Always use jack stands under the truck Lift and stabilize the portion of the ve hicle to be worked on with the proper jack and jackstand 3 Remove the tires and wheels on the side of the axle to be worked on 4 With the parking brake released back off the brakes on this side and then re move the brake drum Service Procedures 5 Disconnect the wheel speed sensor harness from the truck harness and remove any securing tie straps and then use special tool J 44769 to re move the sensor from the vehicle J 44769 6 Install the replacement wheel speed sensor using special tool J 44769 and route the replacement harness connect and secure with tie straps J 44769 J 42942 Note Special tool J 42942 can be used to adjust the sensor without the removal of the wheels or brake drum 7 Install the brake drum 8 Reinstall the removed wheels and tires and using a small screwdriver adjust the brakes 9 Assuring that the jack is in a safe loca tio
43. o ABS ECU stud nuts and remove the ABS ECU from the vehicle 6 Remove the three mounting bracket bolts from the ABS ECU 7 Install the mounting bracket on the re placement ABS ECU 8 Install the replacement ABS ECU on the vehicle 9 Secure the channeled wiring har nesses to the support bracket with tie straps 10 Connect the three ABS ECU connec tors 11 Always connect the main battery ground first If there are other ground cables connected to the battery such as engine ECU satellite system etc connect those grounds last Electronic modules may be damaged when additional grounds are con nected disconnected without the main battery ground connected Reconnect the engine ECU ground wire Connect the negative battery ca bles and install the battery box cover 58 Service Procedures Group 593 ABS ECU Connectors Appendix ABS ECU Connectors Cab Gray ECU Connector Pin Circuit No Description 1 777A 12V Supply 2 777B 12V Supply 3 774 Traction Control System TCS Lamp 4 400 J1587 1708 Data Link 5 772 Engine Brake Disable not used with J1939 6 407 J1939 L 7 406 J1939 H 8 779A Trailer ABS Warning Lamp 9 401 J1587 1708 Data Link 10 778 ABS Warning Lamp Enable 11 ABS A Ground 12 ABS B Ground Front Black ECU Connector Pin Circuit No Description 2 733 LF Modulator Hold 3 752 RF Modulator Exhaust
44. or continuity to the ground bus bar in the electrical center TCS light flashing TCS switch pressed once Normal operation Traction control in Mud snow mode Press switch a second time to disengage mud snow mode or cycle ignition off and on TCS light stays illuminated Short circuit in TCS switch Disconnect TCS switch and cycle ignition off and on Short circuit in harness Disconnect the instrument cluster RH connector green 22 way for the TCS lamp Check circuits 774 774 A and 774 B for short to ground ABS Indicator Light Troubleshooting the ABS indicator lamp works as follows Ignition ON Normal Operation ABS lamp comes on at igni tion momentarily for a bulb check then goes out System is O K After servicing ABS ABS lamp does not go out at ignition When vehicle is driven at speeds above 4 mph 6 km h lamp goes out System is O K Off road ABS opera tion Refer to Off Road ABS in this section ABS lamp flashes during ve hicle operation The vehicle s normal ABS function is being modified due to road conditions Existing Fault ABS lamp does not go out at ignition Lamp does not go out at speeds above 4 mph 6 km h a fault exists in the ABS sys tem 45 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Trailer ABS Indicator Lamp The trailer ABS indicator lamp on the vehicle dash
45. or the VHD is powered through the same ignition circuit 196B as R7 PR3 with the 40A maxi fuse and 5A fuse The relay coil is controlled by the 778 circuit from the ABS ECU which is a ground signal R3 provides a ground from the bus bar to the 779 circuit in the instru ment cluster to turn the warning lamp off Relay R3 R9 can also be used to request blink codes and clear fault codes See Diagnosing Faults using Blink Codes page 33 and Clearing Fault Codes by Removing R3 R9 page 38 Relay location in TEC in center dash Wiring The wiring for the ABS is incorporated in the main cab and chassis wiring harnesses Refer to VN VHD Series Electrical Schematics for more information on routing and location of ABS wiring 21 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Instrumentation ABS Warning Lamp Tractor An amber ABS warning lamp is provided in the instru ment cluster Its function is to notify the operator that the ABS system has detected an unusual condition or fault in the system The lamp will illuminate under the follow ing conditions e When the ignition switch is turned ON the lamp comes ON momentarily for a bulb check then goes out After servicing the ABS the lamp will stay ON until the vehicle speed reaches approximately 11 km h 7 mph then the lamp goes out e f the ABS self monitoring circuits detect a fault in the system e To display ROCKWELL WABCO blink codes for trou
46. ore beginning any service work on any part of the air system be certain that the air pressure has been released Failure to do so may cause a component to violently separate which can result in serious per sonal injury Drain the complete air system 3 Remove any tie straps securing the airlines plumbed to this relay valve 54 Service Procedures 4 Disconnect the six airlines with the push lock fittings using special airline release tools J 44773 and J 42189 J 44773 J 42189 5 Remove the two torque bolts that mount the brake relay valve mount bracket 6 Snug the brake relay valve in a vice and remove all six airline fittings J 44775 7 Snug the replacement relay valve in a vice and install the six airline fittings using pipe sealant J 44775 8 Install the replacement relay valve onto the vehicle 9 Connect the six airlines Note Push airline in completely and remove to insure proper seal 10 Replace all removed tie straps to se cure the airlines plumbed to the relay valve 11 Start the engine to build the air sys tem in order to check for leaks and proper operation Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU 5939 03 02 02 Wheel Speed Sensor Replace ment Rear Axle Before beginning this procedure read the General Work Practices section General Work Practices page 49 for further procedural information 1 AN DANGER Before worki
47. pearance of having a pulsating action In addition to the outputs provided to the modulator valves the ABS ECU supplies inputs to the engine ECU for Traction Control and to the J1587 1708 Data Link for the instrument cluster lights and diagnostics The ECU is housed in a sealed enclosure that protects the electronic circuits from the environment The stresses on the cables resulting from vehicle operation are taken up by the ECU housing which supports each cable as it exits the housing The ECU housing is mounted to the rear of the intermediate crossmember 20 Design and Function Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Design and Function Electrical Fuses The two power inputs to the ABS ECU are fused through individual 10 amp in line fuses These fuses are located on the crossmember near the ECU The power to the in line fuses 1 comes from the ignition circuit via the Ig nition power relay PR3 for the VHD Also attached is a Terminating Resistor 2 For more information refer to page 27 In line fuses and Terminating Resistor Relays Relays are mounted in the Truck Electrical Center TEC in the center dash The ABS ECU Power Relay R7 and PR3 are battery powered through a 30A maxi fuse Re lay R7 PR3 is energized by the ignition circuit 196B through a 40A maxi fuse and a 5A fuse R7 PR3 is grounded to the bus bar The ABS Warning Lamp Relay R3 for the VN and R9 f
48. ponents 4 If resistance in Step 3 was not within tolerance for 3 Measure the resistance across terminals listed on any valve perform Steps 5 through 6 Otherwise go to Step 7 Disconnect the connector on that valve Measure the resistance across terminals 1 1 and 2 and across terminals 1 and 3 the table below Acceptable reading is between 8 0 and 14 0 Q Note See tion page 59 for connector terminal loca 1 r 4 If resistance in Step 3 was not within tolerance for If both resistance values are outside tol either valve perform Steps 5 through 7 Otherwise erance the modulator valve must be i go to Step 8 replaced If the resistance values are AS correct the problem is in the cable 2 3 5 Disconnect the connector on that valve 7 Reconnect the connector 6 Measure the resistance across terminals 1 and 2 7 If resistance value is not within tolerance the To check that the ABS valves are operating properly per Traction Control valve must be replaced If the resis form the following tance value is correct the problem is in the cable 1 Apply the brakes 8 Reconnect the connector 39 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Troubleshooting ABS Traction Valve Resistance Component ABS ECU Con Terminals Satisfactory Possible Faults nector Resistance ABS inlet left front axle Front black har 11 to 2 t ABS exh
49. rocedural information AN DANGER Before working on a vehicle set the parking brakes place the transmission in neutral and block the wheels Failure to do so can result in unexpected vehicle movement and can cause serious personal in jury or death Removal 1 Park the vehicle on a level surface ap ply the parking brake and block the wheels Ensure vehicle ignition is OFF 2 Bleed the air pressure from systems A and B 3 Disconnect the electrical connector from the valve Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Traction valve mounted on LH frame rail at rear crossmember Disconnect the air supply and dis J 42189 charge lines from the valve fittings by pushing in on the air line and fitting collar with release tool J 42189 and pulling on the air line If air pressure is still in the system it is difficult to re lease the air line Be sure to drain all air before starting procedure 5 Remove the 2 valve mounting bolts 6 Release the exhaust air line from the valve using release tool J 42189 and remove the valve 7 Remove the air line fittings from the ATC ATO valve Note the position of the fittings for correct installation and alignment of air lines Installation 1 Apply sealant to the fitting threads In stall the fittings in the original position for connecting the air lines 2 Connect the air line for the exhaust port on the ATC va
50. s either via telefax or mailing directly to the address listed below To From Volvo Trucks North America INC eesssssee IIIImmemeeeennnehhhenehyennn Dept 516 Service Publications 2222526 7900 National Service Road 1 1 222mm RO Box20115b aaa eaa raare fiir Greensboro NC 27402 6115 1 22221 nnenenrnn nennen nnne USA Fax 336 393 3170 Comments proposals 5631 03 02 25 5635 03 02 01 5635 03 02 04 5931 03 02 01 5932 05 03 01 5939 03 02 01 5939 03 02 02 5939 03 02 03 Operation Numbers ABS ATC Valve Replacement nn on nn 52 ABS Modulator Valve Replacement 222258 51 ABS Relay Valve Replacement 2200522250 54 ABS ECU Replacement 4 54x ok 000 ae ska daa SRL AO eR ca 57 ABS Sensor Adjustment 2 2 2 22 nn socor m aea 50 Wheel Speed Sensor Replacement Steer Axle 56 Wheel Speed Sensor Replacement Rear Axle 55 Wheel Speed Sensor Replacement Heavy Duty Axle and or Aluminum Hub 57 VOLVO Volvo Trucks North America Inc P O Box 26115 Greensboro NC 27402 6115 Volvo Trucks Canada Ltd 6490 Vipond Drive Mississauga Ontario L5T 1W8 http www volvotrucks volvo com PV776 TSP154520 1000 6 2001 O Volvo Trucks North America Inc 2001
51. t Medical experts do not agree about potential long term risks from working with and inhaling non asbestos fibers Some experts think that long term exposure to certain non asbestos fibers could cause diseases of the lung including pneumoconiosis fibrosis and cancer There fore it is recommended that workers use caution to avoid creating and breathing dust when working on brakes that contain non asbestos fibers Before beginning any service work on any part of the air system be certain that the air pressure has been released Failure to do so may cause a component to violently separate which can result in serious per sonal injury Observe the following precautions when working with brakes and brake lining material 1 Whenever possible work on brakes in an area sep arate from other operations 2 Always wear a respirator approved by NIOSH or MSHA during all brake service procedures Wear the respirator from removal of the wheels through assembly 3 Never use compressed air or dry brushing to clean brake parts or assemblies OSHA recommends that brake enclosures be used These enclosures have vacuums with High Efficiency Particulate Air HEPA filter and worker arm sleeves If such equipment is not available carefully clean brake parts and as semblies in the open air 4 Clean brake parts and assemblies in the open air During disassembly carefully place all parts on the floor to avoid getting dust into the air Use an ind
52. t faults Intermittent faults are those that oc curred in the system and have not been repaired but are no longer present such as a temporary open sensor circuit that might be caused by a loose connector If the fault is existing the details of the fault will be stored in the ABS ECU memory and will remain there until the fault has been repaired and the technician clears the fault memory If the fault was intermittent the System stores the details of the fault but the fault may be cleared from memory without repair Following detection of any fault the ABS warning lamp will come ON and stay on until the ignition is switched OFF The warning lamp will remain ON when the ignition is on until the fault is repaired and cleared The ABS ECU can store the details of several faults al though they are not necessarily stored in the order they are received If using the blink codes for display of faults the faults must be repaired and cleared from memory one at a time in order to display additional faults The ABS warning lamp will not go out when driving until all faults have been corrected and cleared Note Proper ABS ATC operation requires that front and rear tire size be within 1496 of one another Exceeding this range without electronically resetting the ECU may cause the ABS warning lamp to illuminate and the sys tem to deactivate 24 Design and Function Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Tr
53. t wheels from locking up when the brakes are ap plied with great intensity under normal road conditions or when applied normally on slippery road surfaces The ABS electronically monitors the rotational speed of both front wheels and the wheels on the rear axle The wheel rotation signals are sent to an Electronic Control Unit ECU which sends signals to the ABS modulator valves if it detects that a wheel has locked up or is about to lock up The modulator valves control the pressure to the service brake chambers Wheel rotation is determined by an electronic sensor mounted on the brake spider by a bracket A signal is generated by the sensor as teeth on a tooth wheel which is mounted on the wheel hub pass by the sensor When the ECU senses that a wheel or set of wheels is about to lock during braking a signal is sent to the ap propriate modulator valve solenoid to intermittently open and close it This opening and closing occurs very rapidly several times per second to reduce brake pres sure and ensure that the wheel returns to rotating while still maintaining most of the brake capacity Some vehicles have a Traction Control System ATC in cluded with the ABS The ATC functions to stop a set of drive wheels from spinning when the driver attempts to accelerate the vehicle from a stand still or when a wheel is spinning due to road conditions such as ice or loose gravel under the wheel The ATC requires an additional valve that al
54. tance value is correct the problem is in the cable Reconnect the connector ABS Sensor Resistance Sensor ABS ECU Connector Terminals Satisfactory Possible Faults Location Resistance Left Front Axle 1 Front black harness 7t08 connector Right Front Axle 1 5 to 6 Wiring between ECU and sensor damaged Left Rear Axle 2 Rear green harness 1102 700 to 3000 2 Damaged sensor con connector nector Right Rear Axle 2 3104 Defective sensor Left Rear Axle 3 6 channel brown har 3 to 4 ness connector Right Rear Axle 3 5 to 6 Only used in 6S 4M setup 41 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Troubleshooting Sensor Adjustment Check To check the proper adjustment of a sensor perform the 4 Measure the AC voltage across terminals listed on following the table below Acceptable reading is greater than 0 200 VAC and steady 1 Verify that the vehicle ignition is OFF Note See page 59 for connector terminal loca tion 2 Disconnect the cable to the sensors at the ECU connector for front or rear sensors as appropriate 5 If voltage in Step 4 was not acceptable perform Step 5 through 7 Otherwise go to Step 8 6 Refer to the table below for possible causes AN DANGER 7 Adjust or replace the sensor as required If placing a vehicle with Traction Control System ATC 8 Recheck sensor adjustment on jacks when servicing the ATC m
55. tem ROCKWELL WABCO with E Version ECU Specifications Specifications Electronic Control Unit Make Model 2 c ecce ee Fre edel Rockwell WABCO Series E Power requirement 2 32 34 3 eee tege ite lid 12 VDC two 10 amp fuses in line ABS ECU power relay nnne nne Relay R7 VN Power Relay PR3 VHD Inputs Wheel speed information unneesssnessnnesnnnnnsnnnnnnnnnnnnnnnnnnn nennen nnnnn nn 100 pulses per wheel revolution variable voltage Traction control 5 3 2 utet ER Dee RR e t RD dte di tees lad ee linie mode selection via dash switch Outputs ABS Modulator valve signal er lila pulsating on off Traction control solenoid licita iode te on off Engine EG cuca reduces engine torque Traction Control System Engine ECU via SAE J1939 see note reduces engine torque Traction Control System Data Link uta Edere prece dee cre Red SAE J1587 J1708 diagnostic information to instrument cluster D ta Lirik 22 ian feeling egets SAE J1939 retarder interrupt and traction control functions Dash Lights u 2 2 2 28 en Tractor ABS warning light via relay R3 TCS warning light VN li Tractor ABS warning light via relay R9 TCS warning light VHD OOO AN Trailer ABS Warning light Available with Volvo engines from 1 1998 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Tools Special Tools The following special tools may be required for work on the Anti Lock Braking System The tools can
56. to it Voltage and current spikes associated with welding could damage the ve hicle electrical system If welding must be performed on any structure on or in contact with the vehicle fol low the recommendations below e Disconnect both negative and positive battery cables Ensure the cables remain separated and are not in contact with the vehicle chassis e Disconnect wiring harnesses from all Electronic Control Units ECUs on the vehicle e Disconnect the main wiring harnesses at the LH and RH pass throughs to the cab 49 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU 5932 05 03 01 ABS Sensor Adjustment Before beginning this procedure read the General Work Practices section General Work Practices page 49 for further procedural information AN DANGER Before working on a vehicle set the parking brakes place the transmission in neutral and block the wheels Failure to do so can result in unexpected vehicle movement and can cause serious personal in jury or death ES D 50 Service Procedures Potential sensor damage DO NOT use a screwdriver or sharp instrument to adjust sensor Use of sharp in strument could cause sensor damage Slide the open end of a blunt instru ment such as a dowel rod through the sensor opening in the brake spider un til it rests against the sensor the ABS Sensor Adjustment Tool J 42942 will go in the hole at a slight angl
57. ulk Codes anne 37 Component Troubleshooting 39 Other Component Troubleshooting 43 ABS Indicator IgE ana 45 Trailer ABS Indicator Lamp 46 Service Procedures nu 49 General Work Practices _ 22200u0444nsnnn nennen 49 ABS Sensor Adjustment eiii 50 ABS Modulator Valve Replacement 51 ABS ATC Valve Replacement 52 ABS Relay Valve Replacement 54 Wheel Speed Sensor Replacement Rear Axle 55 Wheel Speed Sensor Replacement Steer Axle 56 Wheel Speed Sensor Replacement Heavy Duty Axle and or Aluminum Hub 57 ABS ECU Replacement aan 57 o A O Deere 59 A 59 ABS ECU Gonnetlers our 59 Feedback Operation Numbers Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU General General Anti Lock Brake System with the E Version ECU This manual contains service information for the E version Meritor WABCO Anti Lock Braking System ABS and ABS with Automatic Traction Control ATC for trucks tractors and buses The E version ABS incorporates the Power Line Carrier Communi cation PLC an optional feature that allows tractor trailer communication For the driver this means that a trailer ABS indicator lamp located on the vehicle dash will come on if a fault occurs in the trailer ABS Group 59 Anti Lock Brake Sys
58. us trial vacuum cleaner with a HEPA filter system to clean dust from the brake drums torque plate spi der and other brake parts After using the vacuum remove any remaining dust with a rag soaked in wa ter and wrung until nearly dry 5 Avoid grinding or machining brake linings 6 Properly clean the work area Never use com pressed air or dry sweeping to clean the work area Use an industrial vacuum with a HEPA filter and rags soaked in water and wrung until nearly dry Dispose of rags with care to avoid getting dust into the air Use an approved respirator when emptying vacuum cleaners and handling rags 7 After working on brakes workers should wash their hands before eating drinking or smoking Clothes worn during brake maintenance should not be worn home Vacuum work clothes after use and launder them separately without shaking to prevent fiber dust from getting into the air 8 Material Safety Data Sheets MSDS on this prod uct as required by OSHA are available from the brake lining manufacturer Note Before servicing the vehicle disable the ATC by disconnecting the harness at the ATC control valve Before beginning any service work on any part of the air system be certain that the air pressure has been released Failure to do so may cause a component to violently separate which can result in serious per sonal injury It is preferable to avoid welding on a truck or tractor or on components attached
59. ust be disabled If the ATC is not disabled and one of the wheels starts to spin the ATC will compensate and the vehicle may come off the jack and may cause serious personal in jury or death Note Before servicing the vehicle disable the ATC by disconnecting the harness at the ATC control valve Spin the wheel for the sensor to be checked by using the Sensor pin out tool J 42883 at approxi mately 30 RPM ABS Sensor Adjustment Check Sensor ABS ECU Connector Terminals Satisfactory Possible Faults Location Condition Left Front Axle 1 Front black harness 7108 No voltage connector e sensor wire broken Right Front Axle 1 5 to 6 gt 0 200 VAC sensor wire shorted Left Rear Axle 2 Rear green harness 1102 e sensor gap too large connector Large variations Right Rear Axle 2 3 to 4 e excessive tooth wheel F runout Left Rear Axle 3 6 channel a har 3 to 4 e tooth wheel damaged Right Rear Axle 3 NESS OST 5106 e excessive wheel bearing end play Only used in 6S 4M setup 42 Group 59 Anti Lock Brake System ROCKWELL WABCO with E Version ECU Other Component Troubleshooting AN DANGER Before working on a vehicle set the parking brakes place the transmission in neutral and block the wheels Failure to do so can result in unexpected vehicle movement and can cause serious personal in jury or death Note Refer to the system schematics
60. vehicle may also include traction control The Traction Control System ATC uses the same wheel sensors as the ABS to determine if one drive wheel is spinning much more rapidly than the others If the ATC determines that a wheel is spinning and the vehicle Speed is below 40 km h 25 mph it opens the relay valve to apply some braking force to stop the wheels from spinning If all drive wheels are spinning the system sends a sig nal to the engine ECU to reduce the engine torque to provide improved traction This action helps reduce the amount of wheel spin and gives the driver greater vehi cle control To prevent the wheel brake from overheating the differ ential brake threshold is increased linearly at vehicle speeds exceeding 35 km h 22 mph Slip is controlled by engine reduction Also when the vehicle speed exceeds 50 km h 31 mph the differential brake control doesn t start but relies on the already existing brake control The traction control system includes an extra relay valve mounted on the left hand frame rail close to the rear crossmember ATC Mud Snow Function The ATC includes a ATC mud snow option switch la beled as shown It is a momentary switch In the normal position the ATC operates normally to increase traction to the spinning wheels When the switch is pressed once the ATC lamp on the dash will blink continuously to indicate that the ATC is in mud snow mode The mud snow function increases available tr

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