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OPERATING INSTRUCTIONS

1. To measure Duty Cycle see Fig 14 1 Insert BLACK test lead into COM test lead jack 2 Insert RED test lead into V gt tQQ test lead jack 3 Connect RED test lead to ON OFF switching side of device 4 Connect BLACK test lead to a good vehicle ground 5 Turn multimeter rotary switch to DUTY CYCLE position 6 View reading on display Section 2 Using your digital Engine Analyser for Automotive Testing The digital multimeter is a very useful tool for trouble shooting automotive electrical sys tems This section describes how to use the digital multimeter to test the starting and charging system ignition system fuel system and engine sensors The digital multimeter can also be used for general testing of fuses switches solenoids and relays General Testing The digital multimeter can be used to test tuses switches solenoids and relays Testing Fuses This test checks to see if a fuse is blown You can use this test to check both the internal fuses inside this digital multimeter To test Fuses see Fig 15 1 Insert BLACK test lead into COM test lead jack 2 Insert RED test lead into J V gt 0C test lead jack 3 Turn multimeter rotary switch to 200 function 4 Touch RED and BLACK test leads to gether to test continuity Listen for tone to verify proper operation 5 Connect RED and BLACK test leads to opposite ends of fuse Listen for tone 13 If you
2. Make sure boot bonnet and interior lights are all OFF See Fig 19 2 Insert BLACK test lead into COM test lead jack 3 Insert RED test lead into 15A test lead jack 4 Disconnect positive battery cable 5 Connect RED test lead to positive battery terminal Connect BLACK test lead to positive battery cable NOTE Do not start vehicle during this test because multimeter damage may result Turn multimeter rotary switch to 15A DC position or try 200mA range View reading on display e Typical current draw is 100mA 1mA 0 001A e Referto vehicle service manual for manu facturers specific Engine Off Battery Cur rent Draw NOTE Radio station presets and clocks are accounted for in the 100mA typical current draw Test Results Normal Current Draw Display reading in Step 8 is within manufacturers specifica tions Excessive Current Draw Display reading in Step 8 is well outside manufacturers specifications Remove Fuses from fuse box one at a time until source of excessive current draw is located Non Fused circuits such as headlights relays and solenoids should also be checked as possible current drains on battery When source of excessive current drain is found service as necessary Cranking Voltage Battery Load Test This test checks the battery to see if it is delivering enough voltage to the starter mo tor under cranking conditio
3. Start engine and let idle e Display reading should increase in voltage from Key On En gine OFF for DC type MAF sensors increase in RPM from Key On Engine OFF for Low Frequency type MAF sen sors e Rev Engine Display reading should increase in voltage from Idle for DC type MAF sensors increase in RPM from Idle for Low Frequency type MAF sensors e Refer to vehicle service manual for charts relating MAF sensor voltage or frequency RPM to increasing air flow Use equation above for Frequency and RPM conversions Test Results Good Sensor e Sensor output voltage or frequency RPM are within manufacturers specifi cations at Key ON Engine OFF e Sensor output voltage or frequency RPM increase with increasing air flow Bad Sensor Sensor output voltage or frequency RPM are not within manufacturers specifications at Key ON Engine OFF Sensor output voltage or frequency RPM do not change with increasing air flow 35 SPECIFICATIONS Accuracy is of reading number of digit at 23 5 C lt 5 RH 0 10000 RPM 2 1 DC Voltage Overload protection 250VDC AC RMS 200mV 2V 20V 200V 0 8 1 Impedance 10MQ Dwell 1 5 1 4 Cyl 0 90 0 Resistance 5 Cyl 0 72 0 2009 2kQ 20k 200kQ 6 Cyl 0 60 0 1 0 3 8 Cyl 0 45 0 20mQ 1 2 5 Overload protection 250V DC AC Overload protection 250V DC AC RMS RMS DC Current Diode Test 200mA
4. A 1 will appear indicating the multim eter is overranged 7 Switch RED and BLACK test leads and repeat Step 6 8 Test Results If the display showed A voltage drop of 0 volts in both direc tions then the diode is shorted and needs to be replaced A 1 appears in both directions then the diode is an open circuit and needs to be replaced The diode is good if the display reads around 0 5V 0 7V in one direction anda 1 appears in the other direction indi cating the multimeter is overranged Measuring Engine RPM TACH RPM refers to revolutions per minute When using TACH you must multiply the display reading by 10 to get actual RPM if using the X10 range If display reads 200 and the multimeter is set to 4 cylinder TACH the actual engine RPM is 10 times 200 or 2000 RPM If the X1 range is used the reading is actual Fig 12 Typical RPM To measure Engine RPM TACH see Fig 12 1 Insert BLACK test lead into COM test lead jack 2 Insert RED test lead into V gt O test lead jack Connect RED test lead to TACH signal wire If vehicle is DIS Distributorless Ignition System then connect RED test lead to the TACH signal wire going from the DIS module to the vehicle engine computer refer to vehicle service manual for loca tion of this wire Turn Mutimeter rotary switch to DIS Measure RPM TACH while running or cranking For all vehicles with distributors
5. Ignition System Wires 0ccceeeeeee 22 Hall Effect Sensors Switches 23 Magnetic Pick Up Coils ccceceeeeee 24 Reluctance Sensors Ignition Coil Switching Action 25 Fuel System Testing 2 ccecceceseeseeeeeeees 27 Measuring Fuel Injector Resistance 27 Testing Engine Sensors eceecseese 28 Oxygen O Type Sensors sesse 28 Temperature Type Sensors 30 Position Type Sensors Throttle and EGR Valve Position Vane Air FIOW essesesssssseissesrossssssrerissos 31 Manifold Absolute Pressure MAP and Barometric Pressure BARO Sensors 32 Mass Air Flow MAF Sensors 34 SAFETY GUIDELINES TO PREVENT ACCIDENTS THAT COULD RESULT IN SERIOUS INJURY AND OR DAMAGE TO YOUR VEHICLE OR TEST EQUIPMENT CAREFULLY FOLLOW THESE SAFETY RULES AND TEST PROCEDURES Always wear approved eye protection Always operate the vehicle in a well ventilated area Do not inhale exhaust gases they are very poisonous Always keep yourself tools and test equipment away from all moving or hot engine parts Always make sure the vehicle is in park Automatic transmission or neutral manual transmission and that the parking brake is firmly set Block the drive wheels Never lay tools on vehicle battery You may short the terminals together causing harm to yourself the tools or the battery Never smoke or have open flames near vehicle V
6. con nect RED test lead to negative side of primary ignition coil refer to vehicle service manual for location of ignition coil Connect BLACK test lead to a good vehicle ground Turn multimeter rotary switch to cor rect CYLINDER selection Measure engine RPM TACH while en gine is cranking or running View reading on display e If using X1 range display reading is actual RPM Remember to multiply display reading by 10 to get actual RPM if using X10 range If display reads 200 then actual engine RPM is 10 times 200 or 2000 RPM Voltage Drops This test measures the voltage drop across wires switches cables solenoids and con nections With this test you can find excessive resistance in the starter system This resis tance restricts the amount of current that reaches the starter motor resulting in low battery load voltage and a slow cranking engine ai starting Test Procedure see Fig 21 1 Disable ignition system so vehicle won t start Refer to vehicle service manual for disabling procedure Normally this will involve disconnecting the primary of the ignition coil or the distributor pick up coil or the cam crank sensor 2 Insert BLACK test lead into COM test lead jack 3 Insert RED test lead into V gt OQ test lead jack 4 Connect test leads Refer to Typical Cranking Voltage Loss Circuit Fig 21 e Connect RED and BLACK test leads alternately between 1 amp
7. must be at 660 F to operate Completely surround sensor tip with flame to deplete sensor of oxygen Rich Condition 29 e Multimeter display should read 0 6V or greater for Zirconia Type Sen sors an Ohmic Resistance value for Tita nia Type Sensors Reading will vary with flame temperature While still applying heat to sensor move flame such that oxygen can reach sen sor tip Lean Condition Multimeter display should read 0 4V or less for Zirconia Type Sensors an overrange condition for Titania Type Sensors See Setting the Range on page 6 Repeat Step 8 a few times to verify results 10 Extinguish Flame let sensor cool and 1 pn remove test leads Test Results Good Sensor Heater Circuit resistance is within manufacturer s specification Oxygen Sensor output signal changed when exposed to a rich and lean condi tion Bad Sensor e Heater Circuit resistance is not within manufacturer s specification e Oxygen Sensor output signal did not change when exposed to a rich and lean condition Oxygen sensor output voltage takes tonger than 3 seconds to switch from a rich to a lean condition Temperature Type Sensors A temperature sensor is a thermistor or a resistor whose resistance changes with tem perature The hotter the sensor gets the lower the resistance becomes Typical ther mistor applications are engine coolant sen sors intake air
8. that the breaker points remained closed while the camshaft was rotating Today s vehicles use electronic ignition and dwell is no longer ad justable Another application for dwell is in testing the mixture control solenoid on GM feedback carburetors Fig 13 Typical Ignition Coil To measure Dwell see Fig 13 1 Insert BLACK test lead into COM test lead jack 2 Insert RED test lead into V gt t O test lead jack 3 Connect RED test lead to DWELL signal wire If measuring DWELL on breaker point ignition systems connect RED test lead to negative side of primary ignition coil refer to vehicle service manual for loca tion of ignition coil e If measuring DWELL on GM mixture control solenoids connect RED testlead to ground side or computer driven side of solenoid refer to vehicle service manual for solenoid location If measuring DWELL on any arbitrary ON OFF device connect RED test lead to side of device that is being switched ON OFF 4 Connect BLACK test lead to a good vehicle ground 5 Turn multimeter rotary switch to cor rect DWELL CYLINDER position 6 View reading on display Measuring Duty Cycle Duty Cycle refers to the percentage of time a signal is ON verses OFF A signal that is ON half the time has a 50 Duty Cycle Duty Cycle is useful for checking solenoids relays switches fuel injectors and any other component that is switched ON and OFF
9. 1 2 2 Test current 2 1 15A 2 0 5 Test voltage Approx 2 4V Overload protection Fast 0 2A 250V ee fuse Continuity Test foot 20A 250V fuse Audible indication Less than 50Q approx Tachometer GENERAL WARNINGS This equipment has been designed to opearate in the harsh environment close to spark ignition engines but the user should be aware of the following 1 Spark ignition engines and related elecronics can emit hgh levels of interference which could affect electrical items such as radio or televison receivers computers etc 2 Interference emitted from the engine area could be increased by a opening the engine compartment cover b Making an elecrical connectionto the vehice wiring loom or the vehicle battery c Any faulty components particularly those associated with the ignition system The user is therefore advised due to the potential emitting of interference that vehicle maintenance and testing should be undertaken with due care and not in an area close to sensitive electonic equpment 3 If this test equipment behaves in an erratic nature the user is advised t orefer to the advice given in the detailed instrucitons to minimise the possibilityof interference In cases of difficulty the user is advised to check for the followng a A faulty vehicle battery or poor connections to it b Poor ground connection to engine other electrical equipment or this device c Faulty ignition components particularl
10. Fig 4 If we change the mul timeter to the 20KQ range See Fig 5 the display shows a value of 3 87KQ The actual value of resis tance is 3 87KQ and not 4KQ that was measured in the 200KQ range This is very important be cause if the manu facturer specifica tions say that the sensor should read 3 8 3 9KQ at 70 F then on the 200KQ range the sensor would be defective but at the 20KQ range it would test good Now set the multimeter to the 2KQ range See Fig 6 The dis play will indicate an overrange condition because 3 87KQ is larger than 2KQ This example shows that by decreasing the range you in crease the accuracy of your measure ment When you change the range you change the loca tion of the decimal point This changes the accuracy of the measurement by either increasing or decreas ing the number of digits after the decimal point Battery and Fuse Replacement Important A 9 Volt battery must be installed before using the digital multimeter see pro cedure below for installation Battery Replacement 1 Turn multimeter rotary switch to OFF position 2 Remove test leads from multimeter 3 Remove the top screw from back of multimeter 4 Remove back cover 5 Install a new 9 Voli battery 6 Re assemble multimeter Fuse Replacement 1 Turn multimeter rotary switch to OFF position 2 Remove test leads from multimeter 3 Remove the top screw from back of mult
11. bad connections are found replace test leads 5 Connect RED and BLACK test leads across component where you want to measure resistance When making resistance measurements polarity is not important The test leads just have to be connected across the component 6 Turn multimeter rotary switch to de sired OHM range If the approximate resistance is unknown start at the Jargest OHM range and de crease to the appropriate range as re quired See Setting the Range on page 6 7 View reading on display Note range setting for correct units NOTE 2KQ 2 0000 2MQ 2 000 000Q If you want to make precise resistance measurements then subtract the test lead resistance found in Step 4 above from the display reading in Step 7 It is a good idea to do this for resistance measurements less than 10Q Measuring DC Current This multimeter can be used to measure DC current in the range from 0 to 15A and 0 200mA If the current you are measuring exceeds 15A the internal fuse will blow see Fuse Replacement on page 7 Unlike voltage and resistance measurements where the mul timeter is connected across the component Fig 9 Electrical Voltage Source you are testing current measurements must be made with the multimeter in series with the component Isolating current drains and short circuits are some DC Current applications To measure DC Current see Fig 9 1 Insert BLACK test lead into COM test lead jac
12. switched ON and OFF via the ignition module and camshaft crankshaft position sensors This switching action is where the RPM or tach signal originates This test is primarily used for a no start condition Fig 28 Typical Ignition Coil 3 Ground Test Procedure see Fig 28 1 Insert BLACK test lead into COM test lead jack 2 Insert RED test lead into V gt QO test lead jack 3 Connect RED test lead to TACH signal wire If vehicle is DIS Distributorless Ignition System then connect RED test lead to the TACH signal wire going from the DIS 25 module to the vehicle engine computer refer to vehicle service manual for loca tion of this wire e For all vehicles with distributors con nect RED test lead to negative side of primary ignition coil refer to vehicle service manual for location of ignition coil Connect BLACK test lead to a good vehicle ground Turn multimeter rotary switch to cor rect CYLINDER selection in LO TACH View reading on display while engine is cranking Typical cranking RPM range is 150 300 RPM depending on temperature size of engine and battery condition e Refer to vehicle service manual for spe cific vehicle cranking RPM range Test Results Good Coil Switching Action Display read ing indicated a value consistent with manu facturers specifications Less than 150rpm may cause starting problems Bad Coil Switching Action Di
13. tery to sensor POWER pin Connect negative terminal of 9V bat tery to sensor GROUND pin Refer to illustrations for POWER and GROUND pin locations For sensors not illustrated refer to ve hicle service manual for pin locations 3 Insert BLACK test lead into COM test lead jack 23 4 Insert RED test lead into SV gt 0C test lead jack 5 Connect RED test lead to sensor SIG NAL pin 6 Connect BLACK test lead to 9V battery negative pin 7 Turn multimeter rotary switch to 200 function Multimeter should sound a tone 8 Slide a flat blade of iron or magnetic steel between sensor and magnet Use a scrap of sheet metal knife blade steel ruler etc e Multimeter tone should stop and display should overrange e Remove steel blade and multimeter should again sound a tone e It is O K if display changes erratically after metal blade is removed e Repeat several times to verify results 9 Test Results Good Sensor Multimeter toggles from tone to overrange as steel blade is in serted and removed Bad Sensor No change in multimeter as steel blade is inserted and removed 7 Chrysler Distributor Hall Effect POWER GROUND SIGNAL Iron or Steel Blade 4 Ford Distributor O Hall Effect l POWER GROUND SIGNAL Typical Hall Etlect Sensor Magnetic Pick Up Coils Reluctance Sensors Reluctance sensors are used whenever th
14. 2 2 amp 3 4 amp 5 5 amp 6 6 amp 7 7 amp 8 8 amp 9 and 8 amp 10 Fig 21 Typical Cranking Voltage Loss Circuit This is a representative sample of one type of cranking circuit Your vehicle may use a different circuit with different components or locations Consult your vehicle service manual Starter 5 Turn multimeter rotary switch to 200mV DC range If multimeter overranges turn multimeter rotary switch to the 2V DC range See Setting the Range on page 6 6 Crank engine until steady reading is on display Record results at each point as displayed on multimeter Repeat Step 4 amp 5 until all points are checked 7 Test Results Estimated Voliage Drop of Starter Circuit Components Component Voltage Switches 300mV Wire or Cable 200mV Ground 100mV Battery Cable Connectors 50mV Connections 0 0V e Compare voltage readings in Step 6 with above chart If any voltages read high inspect component and connection for defects Ifdefects are found service as necessary Solenoid Charging System Voltage Test This test checks the charging system to see if it charges the battery and provides power to the rest of the vehicles electrical systems lights fan radio etc Test Procedure see Fig 22 1 Insert BLACK test lead into COM test lead jack 2 Insert RED test lead into V QO test lead jack 3 Connect RED test lead to positive terminal of battery 4 C
15. 36 Digital Engine Analyser OPERATING INSTRUCTIONS Index Safety Precautions cccsscssseeeeennereeeees 2 For Vehicle Service Information 004 3 Visual INSP CtION cccecsceesseeeseeeceeeeeeseesees 3 Warranty ymer 36 1 Multimeter Basic Functions Controls and Display cccccceeseeeeeees 4 Setting the Range scsccsceceeseeeeneeeees 6 Battery and Fuse Replacement MA d Measuring DC Voltage 2 cecceseeeeeesee 8 Measuring Resistance cessseeeees 8 Measuring DC Current 2 1csscceeeneees 9 Testing for Continuity 10 Testing Diodes eccesseeseterenseneeeeeee 10 Measuring Engine RPM TACH 11 Measuring Dwell s s ssssssrsresrsresssrsrsesnnnssse 12 Measuring Duty Cycle cceeeeeeeeees 12 2 Automotive Testing with the 4142 General Testing sssesesssesseecceserseeeseres 13 Testing Fuses 13 Testing Switches 13 Testing Solenoids and Relays 14 AUTO POWER OFF i IZ Gunson Digital Engine Analyser ara Part No 4142 Starting Charging System Testing 15 No Load Battery Test 2 ccc 15 Engine Off Battery Current Draw 16 Cranking Voltage Battery Load Test 17 Voltage Drops oo cccecceeeeeeceeeeeeeeee 18 Charging System Voltage Test 19 Ignition System Testing cseceeeeeeeee 20 Ignition Coil Testing 2 0 20
16. Insert BLACK test lead into COM test lead jack see Fig 25 3 Insert RED test lead into V gt tOQ test lead jack 22 Spark Plug Wire Connect RED test lead to one end of ignition wire and BLACK test lead to other end Turn multimeter rotary switch to 200K range View reading on display while flexing ignition wire and boot in several places e Refer to vehicle service manual for your vehicles resistance range As you flex ignition wire the display should remain steady Test Results Good ignition Wire Display reading is within manufacturers specification and remains steady while wire is flexed Bad Ignition Wire Display reading erratically changes as ignition wire is flexed or display reading is not within manufacturers specification Hall Effect Sensors Switches Hall Effect sensors are used whenever the vehicle computer needs to know speed and position of a rotating object Hall Effect sen sors are commonly used in ignition systems to determine camshaft and crankshaft posi tion so the vehicle computer knows the opti mum time to fire the ignition coil s and turn on the fuel injectors This test checks for proper operation of the Hall Effect sensor switch Test Procedure see Fig 26 1 Remove Hall Effect Sensor from ve hicle Refer to vehicle service manual for proce dure 2 Connect 9V battery to sensor POWER and GROUND pins e Connect positive terminal of 9V bat
17. K test lead to sensor GROUND pin e Refer to vehicle service manual for loca tion of sensor POWER and GROUND pins 5 Turn multimeter rotary switch to 20KQ range 6 View and record reading on display e Display should read some resistance value e If multimeter is overranging adjust the range accordingly See Setting the Range on page 6 31 e If multimeter overranges on largest range then sensor is an open circuit and is defective 7 Move RED test lead to sensor SIG NAL pin e Refer to vehicle service manual for location of sensor SIGNAL pin 8 Operate Sensor Throttle Position Sensor e Slowly move throttle linkage from closed to wide open position Depending on hook up the display reading will either increase or de crease in resistance The display reading shouldeither start at or end at the approximate resis tance value measured in Step 6 e Some throttle position sensors have an Idle or Wide Open Throttle WOT switch in addition to a potentiometer e To test these switches follow the Test ing Switches test procedure on page 13 e When you are told to operate switch then move throttle linkage Vane Air Flow Sensor e Slowly open vane door from closed to open by pushing on it with a pencil or similar object This will not harm sensor Depending on hook up the display read ing will either increase or decrease in resistance The display reading should e
18. V DC range then the highest voltage the multimeter can measure is 20V in that range EXAMPLE Measuring Vehicle Battery Volt age See Fig 1 Let s assume the multimeter is connected to the battery and set to the 20V range The display reads 12 56 This means there is 12 56V across the battery terminals Now assume we set the multimeter to the 2V range See Fig 2 The multimeter display now shows a 1 and nothing else This means the multimeter is being overranged or in other words the value being measured is larger than the selected range The range should be increased until a value is shown on the display If you are in the highest range and the multimeter is still show ing that it is overranging then the value being measured is too large for the multimeter to measure How do know what Range the multimeter should be set to The multimeter should be set in the lowest possible range without overranging EXAMPLE Measuring an unknown resis tance Let s assume the multimeter is connected to an engine coolant sensor with unknown re sistance See Fig 3 Start by setting the multimeter to the largest OHM range The display reads 0 09 or a short circuit This sensor can t be shorted so reduce the range setting until you get a value of resis tance At the 200KQ range the multimeter measured a value of 4 0 This means there is 4KQ of resistance across the engine coolant sensor terminals See
19. age range If the approximate voltage is unknown start at the largest voltage range and decrease to the appropriate range as re quired See Setting the Range on page 6 6 View reading on display Note range setting for correct units NOTE 200mV 0 2V Measuring Resistance Resistance is measured in electrical units called ohms Q The digital multimeter can measure resistance from 0 19 to 20MOQ or 20 000 000 ohms Infinite resistance is shown with a 1 on the left side of display See Setting the Range on page 6 You can use this multimeter to do any resistance mea surement called out in the vehicle service manual Testing ignition coils spark plug wires and some engine sensors are common uses for the OHMS Q function Fig 8 Unknown Resistance To measure Resistance see Fig 8 1 Turn circuit power OFF To get an accurate resistance measure ment and avoid possible damage to the digital multimeter and electrical circuit un der test turn off all electrical power in the circuit where the resistance measurement is being taken 2 Insert BLACK test lead into COM test lead jack 3 Insert RED test lead into VOC test lead jack 4 Turn multimeter rotary switch to 20MQ range Touch RED and BLACK multimeter leads together and view reading on display Display should read typically 0 20 to 1 59 If display reading was greater than 1 50 check both ends of test leads for bad connections lf
20. apors from gasoline and charging battery are highly flammable and explosive Never leave vehicle unattended while running tests Always keep a fire extinguisher suitable for gasoline electrical chemical fires handy Always use extreme caution when working around the ignition coil distributor cap ignition wires and spark plugs These components contain High Voltage when the engine is running Always turn ignition key OFF when connecting or disconnecting electrical components unless otherwise instructed Always follow vehicle manufacturers warnings cautions and service procedures CAUTION Some vehicles are equipped with safety air bags You must follow vehicle service manual cautions when working around the air bag components or wiring If the cautions are not followed the air bag may open up unexpectedly resulting in personal injury Note that the air bag can still open up several minutes after the ignition key is off or even if the vehicle battery is disconnected because of a special energy reserve module All information illustrations and specifications contained in this manual are based on the latest information available from industry sources at the time of publication No warranty expressed or implied can be made for its accuracy or completeness nor is any responsibility assumed by Gunson Ltd or anyone connected with it for loss or damages suffered through reliance on any information contained in this manual or misuse o
21. ay reading by 10 to get actual RPM e To convert RPM to Frequency or vice versa use equation below RPM 30 Equation Only Valid for Multimeter in 4 Cylinder X1TACH Position 13 Operate Sensor Frequency e Display reading should decrease in volt age or RPM as vacuum to MAP sensor is increased e Reter to vehicle service manual for charts relating voltage and frequency drop to increasing engine vacuum e Use equation above for Frequency and RPM conversions 14 Test Results Good Sensor Sensor output voltage or frequency RPM are within manufactur ers specifications at 0 in of vacuum e Sensor output voltage or frequency RPM decrease with increasing vacuum Bad Sensor e Sensor output voltage or frequency RPM are not within manufacturers specifications at 0 in of vacuum e Sensor output voltage or frequency RPM do not change with increasing vacuum Mass Air Flow MAF Sensors This sensor sends a signal to the computer indicating the amount of air entering the en gine Depending on the sensor design the signal may be a dc voltage low frequency or high frequency type The CP7678 can only test the dc voltage and low frequency type of MAF sensors The high frequency type sensors output a frequency that is too high for the Digital Engine Analyser to measure Refer to vehicle service manual for the type of MAF sensor your vehicle uses Test Procedure see Fig 34 1 Insert BLACK test lea
22. d into COM test lead jack 2 Insert RED test lead into V tQO test lead jack for DC type or low frequency type MAF sensors 3 Connect BLACK test lead to good ve hicle ground Fig 34 Typical GM 1988 amp older Low Frequency type MAF Sensor 34 Connect RED test lead to MAF signal wire Refer to vehicle service manual for loca tion of MAF signal wire You may have to backprobe or pierce MAF signal wire in order to make con nection e Refer to vehicle service manual for best way to connect to MAF signal wire Turn Ignition Key ON but do not start engine Turn multimeter rotary switch to 20V range for DC type MAF sensors 4 Cylinder TACH position for Low Fre quency type MAF sensors View reading on display DC Volts Type Sensor Display reading should be approximately 1V or less depending on MAF sensor manufacturer Low Frequency Type Sensor Display reading should be approximately 330RPM 5 for GM Low Frequency MAF sensors e For other Low Frequency type MAF sen sors refer to vehicle service manual for MAF sensor specifications e Itis O K if last two display digits change slightly while Key is ON Remember to multiply display reading by 10 to get actual RPM e To convert RPM to Frequency or vice versa use equation below Frequency BPM q y 30 Equation Only Valid for Multimeter in 4 Cylinder TACH Position Operate Sensor
23. d voltage and a slow cranking engine at starting Test Procedure see Fig 21 1 Disable ignition system so vehicle won t Start Refer to vehicle service manual for disabling procedure Normally this will involve disconnecting the primary of the ignition coil or the distributor pick up coil or the cam crank sensor 2 Insert BLACK test lead into COM test lead jack 3 Insert RED test lead into V gt OO test lead jack 4 Connect tesi leads Refer to Typical Cranking Voltage Loss Circuit Fig 21 Connect RED and BLACK test leads alternately between 1 amp 2 2 amp 3 48 amp 5 5 amp 6 6 amp 7 7 amp 8 88 amp 9 and8 amp 10 Fig 21 Typical Cranking Voltage Loss Circuit This is a representative sample of one type of cranking circuit Your vehicle may use a different circuit with different components or locations Consult your vehicle service manual Starter 5 Turn multimeter rotary switch to 200mV DC range lf multimeter overranges turn multimeter rotary switch to the 2V DC range See Setting the Range on page 6 6 Crank engine until steady reading is on display Record results at each point as displayed on multimeter e Repeat Step 4 amp 5 until all points are checked 7 Test Results Estimated Voltage Drop of Starter Circuit Components Component Voltage Switches 300mV Wire or Cable 200mV Ground 100mV Battery Cable Connectors 50mV Connections 0 0V e Compare voltage rea
24. dings in Step 6 with above chart If any voltages read high inspect component and connection for defects Ifdefects are found service as necessary Solenoid Charging System Voltage Test This test checks the charging system to see if it charges the battery and provides power to the rest of the vehicles electrical systems lights fan radio etc Test Procedure see Fig 22 1 Insert BLACK test lead into COM test lead jack 2 Insert RED test lead into V QO test lead jack 3 Connect RED test lead to positive terminal of battery 4 Connect BLACK test lead to negative terminal of battery 5 Turn multimeter rotary switch to 20V DC range 6 Start engine Let idle 19 7 Turn off all accessories and view read ing on display e Charging system is normal if display reads 13 5 to 14 8 volts e If display voltage is not between 13 5 to 14 8 volts then proceed to Step 13 8 Open throttle and Hold engine speed RPM between 1800 and 2800 RPM Hold this speed through Step 11 Have an assistance help hold speed 9 View reading on display Voltage reading should not change from Step 7 by more than 0 5V 10 Load the electrical system by turning on the lights windshield wipers and setting the blower fan on high 11 View reading on display Voltage should not drop down below about 13 0V 12 Shut off all accessories maintain engine speed then return engine to curb
25. e 3 vehicle computer needs to know speed and position of a rotating object Reluctance sen sors are commonly used in ignition systems 4 to determine camshaft and crankshaft posi tion so the vehicle computer knows the opti 5 mum time to fire the ignition coil s and turn on the fuel injectors This test checks the 6 reluctance sensor for an open or shorted coil This test does not check the air gap or voltage output of the sensor Reluctance Sensor Reluctor Ring Magnet Test Procedure see Fig 27 1 Insert BLACK test lead into COM test lead jack 2 Insert RED test lead into V QO test lead jack 24 Connect RED test lead to either sensor pin Connect BLACK test lead to remaining sensor pin Turn multimeter rotary switch to 2KQ range View reading on display while flexing sensor wires in several places Typical resistance range is 150 10009 Refer to vehicle service manual for your vehicles resistance range As you flex sensor wires the dis play should remain steady 7 Test Results Good Sensor Display reading is within manufacturers specification and remains steady while sensor wires are flexed Bad Sensor Display reading errati cally changes as sensor wires are flexed or display reading is not within manufacturers specification Ignition Coil Switching Action This test checks to see if the negative termi nal of the primary ignition coil is getting
26. ect routing Refer to vehicle service manual or Vehicle Emission Control Don t take shortcuts Inspect hoses and Information VECI decal located in the wiring which may be difficult to see due engine compartment to location Pinches and kinks Inspect the air cleaner and ductwork for Splits cuts or breaks particularly at ends defects oy e Inspect wiring for Check sensors and actuators for Contact with sharp edges damage Contact with hot surfaces such as Inspect ignition wires for exhaust manifolds Damaged or corroded terminals Pinched burned cracked or chafed Split or cracked spark plug boots ngulanon Splits cuts or breaks in the ignition Prop r routing and connections wires and insulation e Check electrical connectors for Corrosion on pins Bent or damaged pins Contacts not properly seated in housing Bad wire crimps to terminals Section 1 Multimeter Basic Functions Digital multimeters or DMMs have many special features and functions This section defines these features and functions and explains how to use these functions to make various measurements AUTO POWER OFF Alligator Clip Adapters Some multimeter tests and measurements are more easily done using alligator clips instead of test prods For these tests push the crimp end of the alligator clip onto the test prod If the crimp on the alligator clip becomes loose then remove the alligator clip fro
27. er information Low Battery If this symbol appears in the lower left corner of the display then replace the internal 9V battery See Fuse and Battery replacement on page 7 Overrange Indication If i or 1 appears on the left side of the display then the multim eter is set to a range that is too small for the present measure ment being taken Increase the range until this disappears If it does not disappear after all the ranges for a particular function have been tried then the value being measured is too large for the multimeter to measure See Setting the Range on page 6 i Automatic Power Off The multimeter will automatically turn itself off after approximately fifteen 15 minutes if the rotary switch has not been rotated Mo mentarily change the rotary switch position to restore normal operation Zero Adjustment The multimeter will automatically zero on the Volts Amps and RPM functions Automatic Polarity Sensing The multimeter display will show a minus sign on the DC Volts and DC Amps functions when test lead hook up is reversed Setting the Range Two of the most commonly asked questions about digital multimeters are What_does Range mean and How do know what Range the multimeter should be set to What Does Range mean Range refers to the largest value the multim eter can measure with the rotary switch in that position If the multimeter is set to the 20
28. f accompanying product Gunson Ltd reserves the right to make changes at any time to this manual or accompanying product without obligation to notify any person or organization of such changes Vehicle Service Manuals Sources for Service Information The following is a list of publishers who have additional manuals Some manuals may be available at auto parts stores or your local public library For others you need to write for availability and prices Ask for a contents list or confirm that diagnostic information for Vehicle Electrical Systems is included for vehicles of interest to you Specify manufacturer model engine and year details Vehicle Service Manuals Individual model manuals and Joba AS Specialist subjects Kaerbybrovej 4 Haynes Publishing Group DK 8983 Gjerlev Sparkford Denmark Near Yeovil Somerset BA22 7JJ England Specialist subjects and Suitable specialist manuals have titles such as Electrical Engine Controls Fuel Injection and Electronic Engine Controls Emissions Control Manual or similar Do a Thorough Visual Inspection Do a thorough visual and hands on underhood inspection before starting any diagnostic procedure You can find the cause of many problems by just looking thereby saving yourself a lot of time Has the vehicle been serviced recently Sometimes things get reconnected in the wrong place or not at all Inspect all vacuum hoses for Corr
29. he resistance of the coil could change with temperature This will also help in diagnosing intermittent ignition system problems 16 Test Results Overall Good Ignition Coil Resistance readings in Steps 9 14 and 15 were within manufacturers specification Bad Ignition Coil Resistance readings in Steps 9 14 and 15 are not within manufacturers specification Ignition System Wires This test measures the resistance of spark plug and coil tower wires while they are being flexed This test can be used for distributorless ignition systems DIS provided the system does not mount the ignition coil directly on the spark plug Test Procedure 1 Remove ignition system wires one at a time from engine Always grasp ignition system wires on the boot when removing e Twist the boots about a half turn while pulling gently to remove them e Refer to vehicle service manual for igni tion wire removal procedure Inspect ignition wires for cracks chaffed insulation and corroded ends NOTE Some Chrysler products use a positive locking terminal electrode spark plug wire These wires can only be re moved from inside the distributor cap Damage may result if other means of removal are attempted Refer to vehicle service manual for procedure NOTE Some spark plug wires have the following symbol gt This type of plug wire contains an air gap resistor and can only be checked with an oscillascope 2
30. hear tone Fuse is good If you don t hear tone Fuse is blown and needs to be replaced NOTE Always replace blown fuses with same type and rating Testing Switches This test checks to see if a switch Opens and Closes properly Typical Push Button Switch To test Switches see Fig 16 1 Insert BLACK test lead into COM test lead jack 2 insert RED test lead into V gt QO test lead jack 3 Turn multimeter rotary switch to 200 function 4 Touch RED and BLACK test leads to gether to test continuity Listen for tone to verify proper operation 5 Connect BLACK test lead to one side of switch 6 Connect RED test lead to other side of switch Listen for tone e If you hear tone The switch is closed e If you don t hear tone The switch is open 7 Operate switch Listen for tone If you hear tone The switch is closed If you don t hear tone The switch is open 8 Repeat Step 7 to verify switch operation Good Switch Tone turns ON and OFF as you operate switch Bad Switch Tone always ON or tone al ways OFF as you operate switch Testing Solenoids and Relays This test checks to see if a solenoid or relay have a broken coil If the coil tests good it is still possible that the relay or solenoid are defective The relay can have contacts that are welded or worn down and the solenoid may stick when the coil is energized This test does no
31. idle and shut off 13 Test Results If voltage readings in Steps 7 9 and 11 were as expected then charging system is normal If any voltage readings in Steps 7 9 and 11 were different than shown here or in vehicle service manual then check for a loose alternator belt defective regulator or alternator poor connections or open alternator field current Refer to vehicle service manual for fur ther diagnosis Ignition System Testing The ignition system is responsible for providing the spark that ignites the fuel in the cylinder Ignition system components that the digital multimeter can test are the primary and secondary ignition coil resistance spark plug wire resistance hall effect switches sensors reluctance pick up coil sensors and the switching action of the primary ignition coil Ignition Coil Testing This test measures the resistance of the primary and secondary of an ignition coil This test can be used for distributorless igni tion systems DIS provided the primary and secondary ignition coil terminals are easily accessible Test Procedure 1 If engine is HOT let it COOL down be fore proceeding 2 Disconnect ignition coil from ignition system Seconda Coil i Typical Cylindrical Ignition Coil 3 Insert BLACK test lead into COM test lead jack see Fig 23 4 Insert RED test lead into LV gt tOO test lead jack 5 Turn multimeter rotary switch to 200Q range Connect the tes
32. if sensor tip is plastic View and record smallest reading on display as sensor is heated You may need to decrease the range to get a more accurate reading For all other temperature sensors Start engine and let idle until upper ra diator hose is warm Turn ignition key OFF e Disconnect sensor wiring harness and reconnect multimeter test leads View and record reading on display 12 Test Results Good Sensor Temperature sensors HOT resistance is at least 300Q less than its COLD resis tance e The key point is that the resistance decreases with increasing temperature Bad Sensor e There is no change between the tem perature sensors HOT resistance from the COLD resistance e The temperature sensor is an open or a short circuit Position Type Sensors Position sensors are potentiometers or a type of variable resistor They are used by the computer to determine position and direction of movement of a mechanical device Typical position sensor applica tions are throttle position sensors EGR valve posi tion sensors and vane air flow sensors ical Toyota Throttle Position Sensor Typ POWER GROUNO SIGNAL IDLE SWITCH Test Procedure see Fig 32 1 Insert BLACK test lead into COM test lead jack 2 Insert RED test lead into V QO test lead jack 3 Disconnect wiring harness from sen sor 4 Connect Test Leads Connect RED test lead to sensor POWER pin Connect BLAC
33. imeter Then a further four screws Remove battery Remove back cover Remove fuse located on the PCB NO OO A Replace fuses with same size and type as originally installed Use a 5mm X 20mm 0 2A 250V fast blow fuse ora 6mm X 25mm 20A 250V fast blow fuse as a replacement 8 Re assemble multimeter Measuring DC Voltage This multimeter can be used to measure DC voltages in the range from 0 to 200V You can use this multimeter to do any DC voltage measurement called out in the vehicle ser vice manual The most common applications are measuring voltage drops and checking if the correct voltage arrived at a sensor or a particular circuit To measure DC Voltages see Fig 7 1 Insert BLACK test lead into COM test lead jack 2 Insert RED test lead into V gt OO test lead jack 3 Connect RED test lead to positive side of voltage source 4 Connect BLACK test lead to negative side of voltage source NOTE If you don t know which side is positive and which side is negative then arbitrarily connect the RED test lead to one side and the BLACK to the other The multimeter automatically senses po larity and will display a minus sign when negative polarity is measured If you switch the RED and BLACK test leads positive polarity will now be indicated on the dis play Measuring negative voltages causes no harm to the multimeter 5 Turn multimeter rotary switch to de sired volt
34. isten for tone to verify proper operation 5 Connect RED and BLACK test leads across component where you want to check for continuity Listen for tone If you hear tone Circuit is closed or shorted If you don t hear tone Circuit is open or resistance is more than 27Q 10 Testing Diodes A diode is an electrical component that allows current to only flow in one direction When a positive voltage generally greater than 0 7V is applied to the anode of a diode the diode will turn on and allow current to flow If this same voltage is applied to the cathode the diode would remain off and no current would flow Therefore in order to test a diode you must check it in both directions i e anode to cathode and cathode to anode Diodes are typically found in alternators on automobiles Performing Diode Test see Fig 11 1 Insert BLACK test lead into COM test lead jack 2 Insert RED test lead into V gt 0C test lead jack 3 Turn multimeter rotary switch to 2K diode function 4 Touch RED and BLACK test leads to gether to test continuity Check display should reset to 0 00 5 Disconnect one end of diode from cir cuit Diode must be totally isolated from circuit in order to test its functionality 6 Connect RED and BLACK test leads across diode and view display Display will show one of three things A typical voltage drop of around 0 7V A voltage drop of 0 volts
35. ither start at or end at the approximate resistance value measured in Step 6 Some vane air flow sensors have an idle switch and an intake air temperature sensor in addition to a potentiometer To test idle switch see Testing Switches on page 13 e When you are told to operate switch then open vane door e To test intake air temperature sensor see Temperature Type Sensors on page 30 EGR Valve Position Remove vacuum hose from EGR valve e Connect hand vacuum pump to EGR valve e Gradually apply vacuum to slowly open valve Typically 5 to 10 in of vacuum fully opens valve e Depending on hook up the display read ing will either increase or decrease in resistance e The display reading should either start at or end at the approximate resistance value measured in Step 6 Test Results Good Sensor Display reading gradually increases or decreases in resistance as sensor is opened and closed Bad Sensor There is no change in resis tance as sensor is opened or closed Manifold Absolute Pressure MAP and Barometric Pressure BARO Sensors This sensor sends a signal to the computer indicating atmospheric pressure and or en gine vacuum Depending on the type of MAP sensor the signal may be a dc voltage or a frequency GM Chrysler Honda and Toyota use a dc voltage MAP sensor white Ford uses a frequency type For other manufactur ers refer to vehicle service manual for type of MAP sen
36. k 2 Insert RED test lead into 15A test lead jack 3 Disconnect or electrically open circuit where you want to measure current This is done by Disconnecting wiring harness Disconnecting wire from screw on type terminal Unsolder lead from component if work ing on printed circuit boards Cut wire if there is no other possible way to open electrical circuit 4 Connect RED test lead to one side of disconnected circuit 5 Connect BLACK test lead to remaining side of disconnected circuit 6 Turn multimeter rotary switch to 15A DC position 7 View reading on display If minus sign appears on display then reverse RED and BLACK test leads 8 If reading is less than 0 2 remove the RED lead fromthe 15A jack turn the switch to 200mA and plug in the RED lead to the VQ mA jack position Testing for Continuity Continuity is a quick way to do a resistance test to determine if a circuit is open or closed The multimeter will beep when the circuit is closed or shorted so you don t have to look at the display Continuity checks are usually done when checking for blown fuses switch operation and open or shorted wires To measure Continuity see Fig 10 1 Insert BLACK test lead into COM test lead jack 2 Insert RED test lead into 1 V gt tOC test lead jack 3 Turn multimeter rotary switch to 200 function 4 Touch RED and BLACK test leads to gether to test continuity L
37. m the test prod and re crimp using a pair of pliers Controls and Display Definitions 1 ROTARY SWITCH Switch is rotated to turn multimeter ON OFF and select a function 2 DCVOLTS Vr This function is used for measuring DC Direct Current Voltages in the range of 0 to 200V 3 oHMS Q This function is used for measuring the resistance of a component in an electrical circuit in the range of 0 10 to 20MQ Q is the electrical symbol for Ohms 4 DIODE CHECK This function is used to check whether a diode is good or bad 5 CONTINUITY TESTS This is also used for fast continuity checks of wires and terminals An audible tone will sound if a wire and terminal are good 6 DC AMPS Av This function is used for measuring DC Direct Current Amps in the range of 0 to 15A OA 7 TEST LEAD JACKS BLACK Test Lead is al ways inserted in the COM jack RED Test Lead is inserted in the jack corresponding to the multimeter rotary COM switch setting AGH VOmA 15A MAX FUSED Always connect TEST LEADS to the multi meter before connecting them to the cir cuit under test 8 TACH This function is used for measuring engine speed RPM 9 DWELL This function is used for measuring DWELL on distributor ignition systems or on solenoids 10 DUTY CYCLE This function is used for measuring DUTY CYCLE on relays solenoids and other ON OFF types of devices 11 DISPLAY Used to display all measurements and multimet
38. ng Remove Oxygen Sensor from vehicle Insert BLACK test lead into COM test lead jack Insert RED test lead into IV O test lead jack 1 wire or 3 wire Ground is sensor housing 2 wire or 4 wire Ground is in sensor wiring harness Titania Type Oxygen Sensor Exposed flat etement Zirconia Type Oxygen Sensor Flutes Test heater circuit If sensor contains 3 or more wires then your vehicle uses a heated O sensor e Refer to vehicle service manual for loca tion of heater pins e Connect RED test lead to either heater pin Connect BLACK test lead to remaining heater pin e Turn multimeter rotary switch to 200Q range View reading on display Compare reading to manufacturer s specification in vehicle service manual Remove both test leads from sensor Connect BLACK test lead to sensor GROUND pin e If sensor is 1 wire or 3 wire then GROUND is sensor housing e lf sensor is 2 wire or 4 wire then GROUND is in sensor wiring harness Refer to vehicle service manual for Oxy gen Sensor wiring diagram Connect RED test lead to sensor SIG NAL pin Test Oxygen Sensor Turn multimeter rotary switch to 2V range for Zirconia Type Sensors 200KQ range for Titania Type Sen sors Light propane torch Firmly grasp sensor with a pair of locking pliers Thoroughly heat sensor tip as hot as possible but not glowing Sensor tip
39. ns Test Procedure see Fig 20 1 Disable ignition system so vehicle won t start Refer to vehicle service manual for disabling procedure Normally this will involve disconnecting the primary of the ignition coil or the distributor pick up coil or the cam crank sensor 2 Insert BLACK test lead into COM test lead jack 3 Insert RED test lead into SV gt 00 test lead jack 4 Connect RED test lead to positive terminal of battery 5 Connect BLACK test lead to negative terminal of battery 6 Turn multimeter rotary switch to 20V DC range 7 Crank engine for 15 seconds continu ously while observing display 8 Test Results Compare display reading in Step 7 with chart below Voltage Temperature 9 6V or greater 70 F and Above 9 5V 60 F 9 4V 50 F 9 3V 40 F 9 1V 30 F 8 9V 20 F 8 7V 10 F 8 5V 0 F If voltage on display corresponds to above voltage vs temperature chart then cranking system is normal If voltage on display does not correspond to chart then it is possible that the battery battery cables starting system cables starter solenoid or starter motor are defective Voltage Drops This test measures the voltage drop across wires switches cables solenoids and con nections With this test you can find excessive resistance in the starter system This resis tance restricts the amount of current that reaches the starter motor resulting in low battery loa
40. onnect BLACK test lead to negative terminal of battery 5 Turn multimeter rotary switch to 20V DC range 6 Start engine Let idle 19 7 Turn off all accessories and view read ing on display e Charging system is normal if display reads 13 5 to 14 8 volts If display voltage is not between 13 5 to 14 8 volts then proceed to Step 13 8 Open throttle and Hold engine speed RPM between 1800 and 2800 RPM Hold this speed through Step 11 Have an assistance help hold speed 9 View reading on display Voltage reading should not change from Step 7 by more than 0 5V 10 Load the electrical system by turning on the lights windshield wipers and setting the blower fan on high 11 View reading on display Voltage should not drop down below about 13 0V 12 Shut off all accessories maintain engine speed then return engine to curb idle and shut off 13 Test Results e If voltage readings in Steps 7 9 and 11 were as expected then charging system is normal If any voltage readings in Steps 7 9 and 11 were different than shown here or in vehicle service manual then check for a loose alternator belt defective regulator or alternator poor connections or open alternator field current Refer to vehicle service manual for fur ther diagnosis Measuring Dwell Dwell measuring was extremely important on breaker point ignition systems of the past It referred to the length of time in degrees
41. sor used To Computer Test Procedure see Fig 33 1 Insert BLACK test lead into COM test lead jack 2 Insert RED test lead into IV tOQO test lead jack for DC type or low frequency type MAP sensors 32 3 Disconnect wiring harness and vacuum line from MAP sensor 4 Connect jumper wire between Pin A on wiring harness and sensor 5 Connect another jumper wire between Pin C on wiring harness and sensor 6 Connect RED test lead to sensor Pin B 7 Connect BLACK test lead to good ve hicle ground 8 Make sure test leads and jumper wires are not touching each other 9 Connect a hand held vacuum pump to vacuum port on MAP sensor 10 Turn Ignition Key ON but do not start engine 11 Turn multimeter rotary switch to 20V range for DC type MAP sensors 4 Cylinder TACH position for Frequency type MAP sensors 12 View reading on display DC Volts Type Sensor e Verify hand held vacuum pump is at 0 in of vacuum e Display reading should be approximately 3V or 5V depending on MAP sensor manufacturer Frequency Type Sensor e Verify hand held vacuum pump is at 0 in of vacuum e Display reading should be approximately 4770RPM 5 for Ford MAP sensors only For other frequency type MAP sensors refer to vehicle service manual for MAP sensor specifications e Itis O K if last two display digits change slightly while vacuum is held constant 33 e Remember to multiply displ
42. splay read zero RPM meaning the ignition coil is not being switched ON and OFF Check ignition system for wiring defects and test crankshaft and or camshaft Testing Engine Sensors In the early 1980 s computer controls were installed in vehicles to enhance perforamnce and to lower emissions and better fuel economy To do its job a computer controlled engine uses electronic sensors to find out what is happening in the engine The job of the sensor is to take something the computer needs to know such as engine temperature and convert it to an electrical signal which the computer can understand The digital multimeter is a useful tool for checking sensor operation The sensor can be checked for a voltage change on the signal pin as the engine is running Warm up the engine fully and check for voltage variation as the throttle is opened closed Oxygen O Type Sensors The Oxygen Sensor produces a voltage or resistance based on the amount of oxygen in the exhaust stream A low voltage high resis tance indicates a lean exhaust too much oxygen while a high voltage low resistance indicates a rich exhaust not enough oxygen The computer uses this voltage to adjust the air fuel ratio The two types of O Sensors commonly in use are Zirconia and Titania Refer to illustration for appearance differ ences of the two sensor types Test Procedure see Fig 30 1 2 3 If engine is HOT let it COOL down before proceedi
43. system consists of the alternator voltage regulator battery and associated wiring and connections The digital multimeter is a usefu tool for checking the operation of these systems No Load Battery Test Before you do any starting charging system 5 Disconnect positive battery cable checks you must first test the battery to 6 make sure it is fully charged Connect RED test lead to positive terminal of battery 7 Connect BLACK test lead to negative terminal of battery 8 Turn multimeter rotary switch to 20V DC range 9 View reading on display 10 Test Results Compare display reading in Step 9 with chart below Voltage Percent Battery is Charged 12 60V Test Procedure see Fig 18 orgreater 190 1 Turn Ignition Key OFF 12AN 15 2 Turn ON headlights for 10 seconds to 1230 20 dissipate battery surtace charge Then 12 15V 25 turn them off again 3 Insert BLACK test lead into COM test If battery is not 100 charged then charge it lead jack before doing anymore starting charging sys 4 Insert RED test lead into V QO0C test tem tests lead jack Engine Off Battery Current Draw This test measures the amount of current being drawn from the battery when the igni tion key and engine are both off This test helps to identify possible sources of exces sive battery current drain which could even tually lead to a dead battery 1 Turn Ignition Key and all accessories OFF
44. t check for those potential problems Relay or Solenoid To test Solenoids and Relays see Fig 17 1 Insert BLACK test lead into COM test lead jack 2 Insert RED test lead into V QO test lead jack 3 Turn multimeter rotary switch to 200 range Most solenoids and relay coil resistances are less than 2000 If meter overranges turn multimeter rotary switch to next higher range see Setting the Range on page 6 Touch RED and BLACK test leads to gether and listen for tone Connect BLACK test lead to one side of coil Connect RED test lead to other side of coil View reading on display e Typical solenoid relay coil resistances are 2000 or less Refer to vehicle service manual for your vehicles resistance range Test Results Good Solenoid Relay Coil Display in Step 7 is within manufacturers specifica tion Bad Solenoid Relay Coil Display in Step 7 is not within manufac turers specifications e Display reads overrange on every ohms range indicating an open circuit NOTE Some relays and solenoids have a diode placed across the coil To test this diode see Testing Diodes on page 10 Starting Charging System Testing The starting system turns over the engine It consists of the battery starter motor starter solenoid and or relay and associated wiring and connections The charging system keeps the battery charged when the engine is running This
45. t leads together Take a reading 6 Now connect test leads as follows e Connect RED test lead to primary igni tion coil positive terminal e Connect BLACK test lead to primary ignition coil negative terminal e Refer to vehicle service manual for loca tion of primary ignition coil terminals 7 View reading on display Subtract test lead resistance found in Step 5 from above reading 8 If vehicle is DIS repeat Steps 6 and 7 for remaining ignition coils 9 Test Results Primary Coil Typical resistance range of pri mary ignition coils is 0 3 2 0Q Refer to vehicle service manual for your vehicles resistance range Secondary Coil Typical Cylindrical Ignition Coil 10 Turn multimeter rotary switch to 200KQ range see Fig 24 11 Move RED test lead to secondary igni tion coil terminal Refer to vehicle service manual for loca tion of secondary ignition coil terminal Verify BLACK test lead is connected to primary ignition coil negative termi nal 12 View reading on display 13 lf vehicle is DIS repeat Steps 11 and 12 for remaining ignition coils 14 Test Results Secondary Coil e Typical resistance range of secondary ignition coils is 6 0 30 0KQ Refer to vehicle service manual for your vehicles resistance range 15 Repeat test procedure for a HOT igni tion coil NOTE It is a good idea to test ignition coils when they are both hot and cold because t
46. temperature sensors trans mission fluid temperature sensors and oil temperature sensors Hair Dryer Typical Intake Air Temperature Sensor Test Procedure see Fig 31 1 If engine is HOT let it COOL down be fore proceeding Make sure all engine and transmission fluids are at outside air temperature be fore proceeding with this test 2 Insert BLACK test lead into COM test lead jack 3 Insert RED test lead into V gt QO test lead jack 4 Disconnect wiring harness from sen sor 5 If testing Intake Air Temperature Sen sor Remove it from vehicle All other temperature sensors can remain on vehicle for testing 6 Connect RED test lead to either sensor pin 7 Connect BLACK test lead to remaining sensor pin 30 8 Turn multimeter rotary switch to de sired OHM range If the approximate resistance is unknown start at the largest OHM range and de crease to the appropriate range as re quired See Setting the Range on page 6 9 View and record reading on display 10 Disconnect multimeter test leads from sensor and reconnect sensor wiring This step does not apply to intake air temperature sensors For intake air tem perature sensors leave multimeter test leads still connected to sensor 1 Heat up sensor If testing Intake Air Temperature Sensor To heat up sensor dip sensor tip into boiling water or Heat tip with a lighter if sensor tip is metal or a hair dryer
47. y rotor arms igniton coils or HT leads with an internal break or with a resistance outside vehicle manufacturers limits d The tocation of the instrument relative to the cables and electrical components WARRANTY This warranty is in addition to the statutory rights of the purchaser Gunson have made every effort to ensure that this product is of the highest quallty and value to the customer However Gunson can accept no responsibility for consequential damage howsoever caused arising from the use of this product All technical enquiries regarding this product should be accompanied by a stamped self addressed envelope Telephone enquiries can be made on the Gunson Helpline 0181 592 1967 Please note that Gunson can not provide technical information or advice or service data on particular motor cars If this product should require service or repair it should be returned to Gunson Ltd Service Dept Coppen Road Dagenham Essex RM8 1NU Please include details of the fault and if possible a daytime telephone number Postage may be refunded UK only and repairs will be completed free of charge for manufacturing defects within one year of purchase Defects due to other than manufacturing faults may be charged for When sending goods for service or repair please give full details of faults requiring attention

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