�ANTI-LOCK BRAKE SYSTEM

�1993 Mitsubishi Montero

1993 BRAKES Mitsubishi Anti-Lock Brakes

Montero

DESCRIPTION

The Anti-Lock Brake System (ABS) is designed to prevent wheellock-up during heavy braking. This allows operator to maintainsteering control while stopping vehicle in shortest distance possible.Major components are hydraulic unit, wheel speed sensors, "G" sensor,Electronic Control Unit (ECU) and ANTI-LOCK warning light. ABS has aself-diagnostic system to indicate a system malfunction and for use insystem trouble shooting.

NOTE: For more information on brake system, see BRAKE SYSTEM article in BRAKES section.

OPERATION

Each wheel sensor sends an AC electrical signal to theElectronic Control Unit (ECU). The ECU reads this information as wheelspeed. When any decelerating wheel speed rate is determined to beexcessive in comparison to other monitored wheels, the hydraulic unitcycles hydraulic brake pressure to each wheel to equalize speed of allwheels. ABS turns itself off when vehicle drops to 4 MPH. Minor lock-up may occur at this point. With engine running and vehicle speed greater than 4 MPH,pump motor will operate for a short period of time and may be heardinside vehicle. During pump motor operation, ABS system is completinga self-check. During ABS system operation, a pulsing brake pedal andvibration in steering wheel and vehicle body may be experienced. Theseconditions are normal.

CAUTION: See ANTI-LOCK BRAKE SAFETY PRECAUTIONS below.

ANTI-LOCK BRAKE SAFETY PRECAUTIONS

* NEVER open a bleeder valve or loosen a hydraulic line while ABS is pressurized * NEVER disconnect or reconnect any electrical connectors while ignition is on. Damage to ABS control unit may result. * DO NOT attempt to bleed hydraulic system without first referring to the appropriate article. * Only use specially designed brake hoses/lines on ABS-equipped vehicles. * DO NOT tap on speed sensor components (sensor, sensor rings). Speed rings must be pressed, NOT hammered into hubs. Striking these components can cause demagnetization or a loss of polarization, affecting the accuracy of the speed signal returning to the ABS control unit. * DO NOT mix tire sizes. Increasing the width, as long as tires remain close to the original diameter, is acceptable. Rolling diameter must be identical for all 4 tires. Some manufacturers recommend tires of the same brand, style and type. Failure to follow this precaution may cause inaccurate wheel speed readings. * DO NOT contaminate speed sensor components with grease. Only use recommended anti-corrosion coating.

* When speed sensor components have been removed, ALWAYS check sensor-to-ring air gaps when applicable. These specifications can be found in each appropriate article. * ONLY use recommended brake fluids. DO NOT use silicone brake fluids in an ABS-equipped vehicle. * When installing transmitting devices (CB’s, telephones, etc.) on ABS-equipped vehicles, DO NOT locate the antenna near the ABS control unit (or any control unit). * Disconnect all on-board computers, when using electric welding equipment. * DO NOT expose the ABS control unit to prolonged periods of high heat (185

�

F/85�

C for 2 hours is generally considered a maximum limit).

BLEEDING BRAKE SYSTEM

BLEEDING PROCEDURES

When bleeding hydraulic system, follow normal manual orpressure bleeding procedures. Bleed brake system in following order:right rear, left rear, Load-Sensing Proportioning Valve (LSPV), rightfront and left front.

ADJUSTMENTS

NOTE: For adjustment information for brake pedal height, free play, parking brake and stoplight switch, see BRAKE SYSTEMarticle in BRAKES section.

WHEEL SPEED SENSOR

Sensor-To-Rotor Gap Adjustment 1) Raise and support vehicle. Remove wheel assembly. On rearaxle, remove caliper assembly and support with wire. Remove rotor.Inspect sensor pole piece for damage. Repair if necessary. If sensorpole piece is okay, check wheel speed sensor-to-rotor gap. 2) Using a feeler gauge, check clearance between speed sensorpole and rotor tooth surface. See Fig. 1. Front sensor clearanceshould be .008-.390" (0.2-1.0 mm). Rear sensor clearance should be .012-.035" (0.3-0.9 mm). If clearance is not within specification,loosen sensor mounting bolt. Adjust sensor position until clearance iswithin specification. Tighten sensor mounting bolt to 84 INCH lbs.(120 N.m).

Fig. 1: Checking Wheel Speed Sensor-To-Rotor Gap (Typical)Courtesy of Mitsubishi Motor Sales of America.

TROUBLE SHOOTING

ANTI-LOCK WARNING LIGHT

1) Turn ignition on. ANTI-LOCK warning light shouldilluminate for one second, and then go out. Turn ignition switch toSTART position. Warning light should come on and stay on. 2) When ignition switch is turned from START to ON position,warning light should illuminate for one second, and then go out. Ifwarning light functions as specified, go to step 3). If warning lightdoes not function as specified, see appropriate trouble shooting test:

* ANTI-LOCK WARNING LIGHT INOPERATIVE. * IGNITION SWITCH IN ON POSITION, WARNING LIGHT REMAINS ON. * IGNITION SWITCH IN START POSITION, WARNING LIGHT INOPERATIVE. * IGNITION SWITCH IN ON POSITION, WARNING LIGHT BLINKS TWICE. IN START POSITION, WARNING LIGHT STAYS ON. WHEN IGNITION SWITCH IS CYCLED FROM START TO ON POSITION, WARNING LIGHT BLINKS ONCE.

3) Test drive vehicle. If ABS light does not come on at lowspeed, go to next step. If ABS light comes on at low speed, motorrelay, solenoid valve or wheel speed sensor malfunction is indicated.Go to step 6). If insufficient braking force or ABS malfunctionexists, go to next step. If none of above symptoms exist, go to step6). 4) Check conventional brake system components for properoperation. Check for mechanical lock of hydraulic unit solenoid valve.Check for plugged hydraulic line in hydraulic unit. Repair or replaceas necessary. If hydraulic unit is okay, go to next step. 5) Ensure wheel speed sensor rotor gap is correct. See WHEELSPEED SENSOR under ADJUSTMENTS. Check for faulty wheel speed sensor.See WHEEL SPEED SENSOR under COMPONENT TESTING. Replace sensor asnecessary. See WHEEL SPEED SENSOR under REMOVAL & INSTALLATION.Inspect ECU wiring. If testing indicates no mechanical or electricalfailures, substitute ECU with known good unit and retest. 6) Enter ABS self-diagnostics, and retrieve codes. SeeRETRIEVING CODES under DIAGNOSIS & TESTING. If no codes are displayed,fault may be intermittent. Attempt to make malfunction reoccur. If nodiagnostic output exists, check for faulty wiring harness between ECUand self-diagnostic connector. Repair or replace as necessary.

NOTE: Trouble shoot warning light in following sequence: * Instrument Cluster Circuit * ECU and Valve Relay.

ANTI-LOCK Warning Light Inoperative 1) If all other warning lights illuminate with ignition on,go to step 3). If other warning lights do not illuminate, check fuseNo. 11 in main fuse panel. If fuse is blown, correct cause of blownfuse, and replace fuse. If fuse is okay, go to next step. 2) Remove instrument cluster. Turn ignition on. Using DVOM,measure voltage between vehicle ground and instrument cluster ABSwarning light terminal No. 107. See Fig. 2. If battery voltage ispresent, repair or replace instrument cluster. If battery voltage isnot present, repair wire harness between junction block and instrumentcluster. 3) Turn ignition off. Check for faulty warning light bulb.Replace bulb as necessary. If bulb is okay, using an ohmmeter, checkfor continuity between instrument cluster connector terminals No. 107and 158. See Fig. 2. If continuity exists, clean and/or repairconnector terminals. If connector terminals are okay, check for opencircuit to ECU and valve relay. Go to steps 4) and 5). If continuitydoes not exist, replace instrument cluster.

4) To check ECU, turn ignition off. Remove ECU connector. ECUis located on right rear wheelwell. See Fig. 17.Turn ignition on.Measure voltage between terminal No. 13 and vehicle ground. SeeFig. 3. If battery voltage is not present, repair circuit betweenwarning light and ECU. If battery voltage is present, substitute ECUwith known good unit and retest. 5) To check valve relay, see HYDRAULIC UNIT RELAYS underCOMPONENT TESTING. If relay is okay, remove hydraulic unit connector.Turn ignition on. Measure voltage between terminal No. 8 and vehicleground. See Fig. 4. If battery voltage is present, go to next step. Ifbattery voltage is not present, repair circuit between ABS warninglight and hydraulic unit. 6) Turn ignition off. Check for continuity between terminalNo. 9 and vehicle ground. If continuity does not exist, repair circuitbetween hydraulic unit and vehicle ground. If continuity exists, checkfor continuity between terminals No. 8 and 9. If continuity exists,check for defective connector. If continuity does not exist, replacehydraulic unit.

Fig. 2: Identifying Instrument Cluster Connector TerminalsCourtesy of Mitsubishi Motor Sales of America.

Fig. 3: Identifying ECU Connector TerminalsCourtesy of Mitsubishi Motor Sales of America.

Fig. 4: Identifying Hydraulic Unit 10-Pin Connector TerminalsCourtesy of Mitsubishi Motor Sales of America.

Ignition Switch In ON Position, Warning Light Remains On (ECU Power Circuit)

1) Enter ABS self-diagnostics. See RETRIEVING CODES underDIAGNOSIS & TESTING. If diagnostic output exists, go to step 9). If nodiagnostic output exists, connect Multi-Use Tester (MUT) to anotherelectronic control system. 2) If MUT can communicate with another electronic controlsystem, go to next step. If MUT cannot communicate with anotherelectronic control system, tester is malfunctioning. Inspectdiagnostic connector for damaged terminals and correct hook-up. Repairas necessary. If diagnostic connector is okay, replace MUT. 3) Check fuse No. 7 in main fuse panel. If fuse is okay, goto next step. If fuse is blown, correct cause of blown fuse, andreplace fuse. 4) Turn ignition on. ABS power relay should energize. Listenif power relay makes a click noise. Power relay is located behindradio. If noise is not heard, go to next step. If noise is heard, goto step 6). 5) Remove ABS power relay. See ABS POWER RELAY under REMOVAL& INSTALLATION. Test ABS power relay. See ABS POWER RELAY underCOMPONENT TESTING. Replace relay if faulty. 6) Disconnect ECU wiring harness connector. Turn ignition on.Measure voltage between terminal No. 6 and vehicle ground. See Fig. 3.If battery voltage is present, go to next step. If battery voltage isnot present, repair open circuit between power relay and ECU. 7) Check for continuity between vehicle ground and terminalsNo. 9, 10, 11 and 112. If continuity exists, go to next step. Ifcontinuity does not exist in any circuit, check for open in vehicleground circuit. Repair or replace wiring harness as necessary. 8) Check for continuity between terminal No. 14 of ECUconnector and terminal No. 4 of diagnostic connector. Also check forcontinuity between terminal No. 15 of ECU connector and terminal No.10 of diagnostic connector. See Fig. 5. If continuity does not exist,check for open between ECU and diagnostic connector. Repair asnecessary. If continuity exists, replace ECU and go to next step. 9) Check for trouble codes. See TROUBLE CODE DEFINITION underDIAGNOSIS & TESTING. If no trouble codes are present, go to next step.If any trouble codes are present, see appropriate CODE under DIAGNOSIS& TESTING. 10) Disconnect ECU connector. If warning light is no longerilluminated, substitute ECU with known good unit and retest. Ifwarning light is still illuminated, disconnect hydraulic unitconnector. 11) If warning light is still illuminated, repair wiringharness or replace instrument cluster. If warning light is no longerilluminated, test valve relay. See HYDRAULIC UNIT RELAYS underCOMPONENT TESTING. Replace valve relay if defective. If valve relay isokay, replace hydraulic unit.

Fig. 5: Identifying Diagnostic Connector TerminalsCourtesy of Mitsubishi Motor Sales of America.

Ignition Switch In START Position, Warning Light Inoperative 1) Remove ABS power relay fuse No. 7 from junction block.

Disconnect hydraulic unit 10-pin connector. Turn ignition on. UsingDVOM, measure voltage between hydraulic unit harness connectorterminal No. 8 and vehicle ground. See Fig. 4. If battery voltage ispresent, go to next step. If battery voltage is not present, repaircircuit between ABS warning light and hydraulic unit. 2) Using ohmmeter, check for continuity between terminal No.9 and vehicle ground. If continuity exists, go to next step. Ifcontinuity does not exist, repair hydraulic unit circuit. 3) Check continuity between hydraulic unit connectorterminals No. 8 and 9. If continuity exists, go to next step. Ifcontinuity does not exist, replace valve relay. 4) Remove valve relay from hydraulic unit. Check forcontinuity between relay terminals No. 87a and 30. See Fig. 14. Ifcontinuity does not exist, replace valve relay. If continuity exists,hydraulic unit wiring harness is faulty. Replace hydraulic unit.

Ignition Switch In ON Position, Warning Light Blinks Twice. In START Position, Warning Light Stays On. When Ignition Switch Is Cycled From START To ON Position, Warning Light Blinks Once 1) Disconnect hydraulic unit wiring harness connector.Disconnect ECU wiring harness connector. Inspect connector terminalsand repair as necessary. 2) Turn ignition on. Measure voltage between ECU connectorterminal No. 13 and vehicle ground. See Fig. 3. If battery voltage isnot present, repair open or shorted circuit between ABS warning lightand ECU. If battery voltage is present, substitute ECU with known goodunit and retest.

DIAGNOSIS & TESTING

RETRIEVING CODES

Scan Tool 1) With ignition off, connect Multi-Use Tester (MB991341) andROM Pack (MB991423) to diagnostic connector, located under driver’sside of dash, and to cigarette lighter socket. See Fig. 6.

Fig. 6: Connecting Multi-Use TesterCourtesy of Mitsubishi Motor Sales of America.

2) Turn ignition on. ABS warning light should come on as ABSgoes into self-diagnostic mode. Read and record all diagnostic output

(trouble) codes from ECU memory. Refer to Multi-Use Tester (MUT)instructions for specific trouble code retrieval procedure. 3) After all trouble codes have been retrieved and recorded,clear codes from ECU memory. Refer to Multi-Use Tester (MUT)instructions for specific trouble code clearing instructions. SeeTROUBLE CODE DEFINITION and appropriate CODE under DIAGNOSIS & TESTINGfor servicing procedure. 4) If trouble codes cannot be cleared, ECU is currentlydetecting a malfunction. If codes can be cleared, problem is eitherintermittent or only appears while driving.

Voltmeter 1) To retrieve stored trouble codes, locate diagnosticconnector under left side of dash. Turn ignition off. Connect analogvoltmeter between diagnostic terminal No. 4 and vehicle groundterminal No. 12 of diagnostic connector. See Fig. 5. Start engine. 2) Stored trouble codes will be indicated by sweeps ofvoltmeter needle. Long sweeps indicate first digit of code; shortsweeps indicate second digit of code. If more than one fault ispresent, lowest number code will be given first. After trouble codehas been retrieved, test indicated component and/or related circuit(if necessary). See TROUBLE CODE DEFINITION and appropriate CODE underDIAGNOSIS & TESTING for servicing procedure.

CLEARING TROUBLE CODES

To clear trouble codes after repairs, disconnect negativebattery cable for at least 10 seconds. Reconnect battery cable andrepeat RETRIEVING CODES to confirm that failure has been corrected.

TROUBLE CODE DEFINITION

TROUBLE CODES TABLE�����������������������������������������������������������������������������������������������������������������������

Code (1) System Affected

11 ....................... Right Front Wheel Sensor (Open)12 ........................ Left Front Wheel Sensor (Open)13 ........................ Right Rear Wheel Sensor (Open)14 ......................... Left Rear Wheel Sensor (Open)15 ............................ Sensor Output Signal Fault16 ..................................... ECU Power Voltage21 ...................... Right Front Wheel Sensor (Short)22 ....................... Left Front Wheel Sensor (Short)23 ....................... Right Rear Wheel Sensor (Short)24 ........................ Left Rear Wheel Sensor (Short)25-27 ............................ 4WD Power Circuit Fault31 .............................. "G" Sensor Power Voltage32 ............................. "G" Sensor Output Voltage33 .............................. Stoplight Switch Circuit41, 43, or 45 ..................... Solenoid Valve Circuit51 ........................................... Valve Relay53 ........................................... Motor Relay63 ............................................ Faulty ECU64 ............................................ Faulty ECU

(1) - See appropriate CODE under DIAGNOSIS & TESTING.�����������������������������������������������������������������������������������������������������������������������

CODE 11, 12, 13 OR 14

Faulty Wheel Speed Sensor Input 1) Trouble code will set if ECU detects wheel speed sensor

has no input signal. Trouble code will also set if wheel sensorvoltage output is low while driving vehicle. 2) Inspect wheel sensor wiring harness for open or poorconnection. Repair or replace if necessary. If no open circuit or poorconnection is found, go to next step. 3) Test wheel speed sensor. See WHEEL SPEED SENSOR underCOMPONENT TESTING. Replace speed sensor as necessary. Ensure wheelspeed sensor-to-rotor gap is within specification. See WHEEL SPEEDSENSOR under ADJUSTMENTS.

CODE 15

Faulty Wheel Speed Sensor Output 1) Test each sensor. See WHEEL SPEED SENSOR under COMPONENTTESTING. If all sensor voltages and resistances are withinspecification, go to next step. If any sensor is malfunctioning,replace speed sensor. See WHEEL SPEED SENSOR under REMOVAL &INSTALLATION. 2) Check each wheel speed sensor-to-rotor gap. See WHEELSPEED SENSOR under ADJUSTMENTS. If all gaps are within specification,go to next step. If any gaps are not within specification, adjustsensor-to-rotor gap. 3) Inspect all wheel speed sensor rotors for damaged andmissing teeth. Replace any damaged rotors. Using an oscilloscope,check wave-form patterns. See Fig. 7. If all rotors are okay, replaceECU. Ensure trouble code does not reset.

Fig. 7: Identifying Abnormal ABS Rotor Wave-Form PatternsCourtesy of Mitsubishi Motor Sales of America.

CODE 16

ECU Power Voltage Start engine. Measure voltage between ECU terminal No. 6 andvehicle ground. See Fig. 3. If less than 10 volts is present, checkfuse contacts and ECU connector. If 10 volts or more is present,measure voltage between ECU terminal No. 62 and vehicle ground. Ifless than 10 volts is present, check fuse contacts and ECU connector.If fuse contacts and ECU connector are okay, substitute ECU with knowngood unit and retest.

CODE 21, 22, 23 OR 24

Faulty Wheel Speed Sensor Output 1) Test each sensor. See WHEEL SPEED SENSOR under COMPONENTTESTING. If all sensor voltages and resistances are withinspecification, go to next step. If any sensor is malfunctioning,replace sensor. See WHEEL SPEED SENSOR under REMOVAL & INSTALLATION. 2) Remove ECU connector. Check wheel speed circuit at ECUconnector. See Fig. 3. See ECU CONNECTOR TERMINAL RESISTANCESPECIFICATION table. If resistance values are not as specified, repairwiring harness. If resistance values are within specifications, go tonext step. 3) Check each wheel speed sensor-to-rotor gap. See WHEELSPEED SENSOR under ADJUSTMENTS. If all gaps are within specification,go to next step. If any gaps are not within specification, adjustsensor-to-rotor gap. 4) Inspect all wheel speed sensor rotors for damaged andmissing teeth. Replace any damaged rotors. Using an oscilloscope,check wave-form patterns and output voltage. See Fig. 8. Outputvoltage should be 0.2 volt (200 mV). If all rotors and wheel speedsensors are okay, substitute ECU with known good unit and retest.

ECU CONNECTOR TERMINAL RESISTANCE SPECIFICATION TABLE�����������������������������������������������������������������������������������������������������������������������

Application ECU Terminals No. Ohms

LF Wheel Speed Sensor 52 & 57 900-1100RF Wheel Speed Sensor 51 & 56 900-1100LR Wheel Speed Sensor 8 & 18 1300-2100RR Wheel Speed Sensor 53 & 58 1300-2100�����������������������������������������������������������������������������������������������������������������������

CODE 25

Free-Wheel Engage Switch Circuit 1) Start engine. Ensure center differential indicator lightoperates correctly when transfer shift lever is moved to desired 4WDpositions. If indicator light operates correctly, go to step 3). Ifindicator light does not operate correctly, go to next step. 2) Turn engine off. Check wiring harness between 4WDindicator control unit, located behind radio, and free-wheel engageswitch, located on right side of front differential housing nearcarrier assembly. If circuit is okay, replace 4WD indicator controlunit. 3) Disconnect ECU connector. Turn ignition on. Using DVOM,check voltage between terminal No. 55 and vehicle ground. See Fig. 3.

In 2WD battery voltage should exist. Battery voltage should not existin 4WD. If voltage is as described, substitute ECU with known goodunit and retest. See ELECTRONIC CONTROL UNIT (ECU) under REMOVAL &INSTALLATION. If voltage is not as described, repair harness betweenECU and free-wheel engage switch.

CODE 26

Center Differential Lock Switch Circuit 1) Start engine. Ensure center differential indicator lightoperates correctly when transfer shift lever is moved to desired 4WDpositions. If indicator light does not operate correctly, go to step3). If indicator light operates correctly, disconnect ECU connector.Using DVOM, check voltage between terminal No. 107 and vehicle ground.See Fig. 3. 2) When center differential is locked, battery voltage shouldnot be present. When center differential is unlocked, battery voltageshould be present. If voltage is as described, substitute ECU withknown good unit and retest. If voltage is not as described, repairwiring harness between ECU and center differential lock detectionswitch. See Fig. 8. Lock switch can be identified by Brown connector. 3) If no indicator lights illuminate, repair 4WD indicatorpower circuit, or check for faulty 4WD indicator control unit. See 4WDCONTROL UNIT under COMPONENT TESTING. If center differential lightilluminates, regardless of position of transfer shift lever, check thefollowing:

* Check for short in center differential lock switch circuit. * Check for faulty center differential lock switch. * Check for short in ECU circuit or faulty ECU. * Check for short in indicator control unit circuit or faulty 4WD indicator control unit. Repair wiring harness or replace component as necessary.

NOTE: When checking for short in ECU circuit, remove ECU connector and ensure 4WD indicator light operates correctly. If 4WD indicator light operates correctly, replace faulty ECU. If 4WD indicator light does not operate correctly, replace faulty 4WD indicator control unit.

4) If center differential light does not illuminate withtransfer shift lever in "4H" position, repair wiring harness between4WD indicator control unit, and center differential lock switch. Checkfor faulty 4WD indicator control unit. 5) If front wheel indicator light does not illuminate withtransfer shift lever in "4H" position, repair wiring harness between4WD indicator control unit and free-wheel engage switch. Check vehicleground wire at engage switch. Check for faulty free-wheel engageswitch.

Fig. 8: Identifying 4WD Indicator Switch LocationCourtesy of Mitsubishi Motor Sales of America.

CODE 27

Rear Differential Lock Circuit (With Differential Lock) 1) Start engine. Ensure rear differential indicator lightilluminates when top of rear differential lock switch, (located belowradio) is pushed. If indicator light illuminates, go to next step. Ifindicator light does not illuminate, turn engine off. Check wiringharness between rear differential lock control unit and reardifferential lock switch. Check rear differential lock control unitpower circuit. See REAR DIFFERENTIAL CONTROL UNIT under COMPONENTTESTING. If circuit is okay, replace rear differential lock controlunit. 2) Disconnect ECU connector. Turn ignition on. Using DVOM,check voltage between terminal No. 108 and vehicle ground. See Fig. 3.When rear differential is locked, battery voltage should not bepresent. When rear differential is unlocked, battery voltage should bepresent. If voltage is as described, substitute ECU with known goodunit and retest. If voltage is not as described, repair wiring harnessbetween ECU and rear differential lock switch.

Rear Differential Without Differential Lock Check fuse No. 18 in main fuse block. Replace if necessary.

Disconnect ECU connector. Turn ignition on. Using DVOM, check voltageat terminal No. 108 and vehicle ground. See Fig. 3. If battery voltageis present, substitute ECU with known good unit and retest. If batteryvoltage is not present, check for open circuit between ECU and fuseblock. Repair wiring harness as necessary.

CODE 31

"G" Sensor Power Voltage 1) If Code 31 is present, and Code 32 is not present,substitute ECU with known good unit and retest. If Code 31 and Code 32are both present, disconnect "G" sensor wiring harness connector. "G"sensor is located under center console. See Fig. 18. Turn ignition toACC switch position. Using ohmmeter, check continuity between "G"sensor harness connector terminal No. 1 (Blue wire) and vehicleground. If continuity does not exist, replace "G" sensor. Ifcontinuity exists, disconnect ECU connector. 2) Check continuity between terminal No. 1 and vehicleground. If continuity exists, repair wiring harness between ECU and"G" sensor. If continuity does not exist, replace faulty ECU.

CODE 32

"G" Sensor Output Signal 1) Park vehicle on level surface. Using Multi-Use Tester,check "G" sensor voltage. Refer to Multi-Use Tester (MUT) instructionsfor specific test procedure. Voltage should be 2 - 3 volts. If voltageis not as described, go to step 3). If voltage is as described, notetop center position of "G" sensor, and remove "G" sensor, locatedunder center console next to shifter. See "G" SENSOR under REMOVAL &INSTALLATION. 2) Check voltage when sensor is tilted 50 degrees to the leftof center. Voltage should be 0.3-0.7 volt. Tilt sensor 50 degrees toright of center and check voltage. Voltage should be 4.3-4.7 volts. Ifvoltage is as described, substitute ECU with known good unit andretest. If voltage is not as described, replace "G" sensor. 3) If "G" sensor voltage is less than 0.2 volt, go to nextstep. If "G" sensor voltage is more than 4.8 volts, go to step 9). If"G" sensor voltage is 0.3-4.7 volts, check for poor vehicle groundconnection (loose mounting bolt) at sensor. Repair as necessary. Ifconnection is okay, replace "G" sensor. 4) Turn ignition on. Using DVOM, check for 7.0-7.5 volts atECU connector terminal No. 103. See Fig. 3. If voltage is asdescribed, go to next step. If voltage is not as described, turnignition off. Disconnect ECU and "G" sensor connectors. Usingohmmeter, check continuity between ECU connector terminal No. 103 andvehicle ground. If continuity exists, repair wiring harness betweenECU and "G" sensor. If continuity does not exist, substitute ECU withknown good unit and retest. See ELECTRONIC CONTROL UNIT (ECU) underREMOVAL & INSTALLATION. See Fig. 17. 5) Disconnect "G" sensor connector. Turn ignition on. Checkfor 7.0-7.5 volts between terminal No. 1 (Blue wire) and vehicleground. If voltage is as described, go to next step. If voltage is notas described, repair wiring harness between ECU and "G" sensor. 6) Connect "G" sensor connector. Check voltage at terminalNo. 3 (Blue/White wire) and vehicle ground. Voltage should be 2-3volts. If voltage is as described, go to step 8). If voltage is not asdescribed, turn ignition to switch ACC position. Disconnect "G" sensorconnector. Using ohmmeter, check resistance between terminal No. 3(Blue/White) and vehicle ground. Resistance should be 500 ohms ormore. If resistance is as described, replace "G" sensor. 7) If resistance is not 500 ohms or more, turn ignition off.Disconnect "G" sensor and ECU connectors. Check continuity between

terminal No. 3 and vehicle ground. If continuity does not exist,substitute ECU with known good unit and retest. If continuity exists,repair wiring harness between ECU and "G" sensor. 8) Turn ignition on. Using DVOM, check voltage at ECUterminal No. 110 and vehicle ground. See Fig. 3. Voltage should be 2-3volts. If voltage is as described, substitute ECU with known good unitand retest. If voltage is not as described, repair wiring harnessbetween ECU and "G" sensor. 9) Disconnect "G" sensor connector. Using ohmmeter, checkcontinuity between terminal No. 2 (Black/Red) and vehicle ground. Ifcontinuity exists, replace "G" sensor. If continuity does not exist,check continuity between ECU terminal No. 111 and vehicle ground. Ifcontinuity exists, repair wiring harness between ECU and "G" sensor.If continuity does not exist, substitute ECU with known good unit andretest.

CODE 33

Stoplight Switch Circuit 1) Check if stoplights are functioning correctly. Ifstoplights function correctly, go to next step. If stoplights do notfunction correctly, check stoplight circuit and repair as necessary. 2) Disconnect ECU connector. Using DVOM, measure voltagebetween terminal No. 109 and vehicle ground while depressing brakepedal. See Fig. 3. If battery voltage is not present, repair orreplace wiring harness between stoplight switch and ECU. Seeappropriate wiring diagram. If battery voltage is present, stoplightswitch circuit is okay. Replace ECU.

CODE 41, 43 OR 45

Solenoid Valve Circuit 1) Disconnect hydraulic unit 10-pin connector. Usingohmmeter, measure resistance between hydraulic unit terminal No. 7 andterminals No. 3, 5 and 6. See Fig. 4. 2) Resistance should be 1000-1300 ohms. If resistance iswithin specification, go to next step. If resistance is not withinspecification, replace faulty hydraulic unit. See HYDRAULIC UNIT underREMOVAL & INSTALLATION. 3) Connect hydraulic unit 10-pin connector. Disconnect ECUwiring harness connector. Measure resistance between ECU terminal No.62 and terminals No. 1, 2 and 3. See Fig. 3. 4) Resistance should be 1000-1300 ohms. If resistance is notwithin specification, repair or replace wiring harness. If allresistance tests are within specification, solenoid valve circuit isokay. Replace ECU.

CODE 51

Valve Relay Circuit 1) Remove and test valve relay. See HYDRAULIC UNIT RELAYSunder COMPONENT TESTING. Replace relay if faulty. If relay is okay,reinstall valve relay and go to next step. 2) Check pump motor, and repair if necessary. Turn ignitionon. Disconnect hydraulic unit 2-pin connector. Measure voltage betweenterminal No. 52 and vehicle ground. See Fig. 9. 3) If battery voltage is not present, repair wiring harnessbetween fusible link and hydraulic unit 2-pin connector. If batteryvoltage is present, turn ignition off. Using ohmmeter, check forcontinuity between hydraulic unit 10-pin connector terminals No. 7 and8. See Fig. 4. If continuity exists, go to next step. If continuitydoes not exist, repair or replace hydraulic unit. 4) Connect hydraulic unit connector. Disconnect ECU

connector. Using ohmmeter, measure resistance between ECU connectorterminals No. 4 and 5. See Fig. 3. Resistance should be 60-120 ohms.If resistance is within specification, go to next step. If resistanceis not within specification, repair wiring harness between hydraulicunit and ECU. 5) Turn ignition on. Measure voltage between ECU connectorterminal No. 62 and vehicle ground. If battery voltage is not present,repair or replace faulty wiring harness between hydraulic unit andECU. If battery voltage is present, replace faulty ECU.

Fig. 9: Identifying Hydraulic Unit 2-Pin ConnectorCourtesy of Mitsubishi Motor Sales of America.

CODE 53

Motor Relay Circuit 1) Using MUT, perform hydraulic unit actuator test. If motoris not operating, go to next step. If motor is still operating, repairor replace wiring harness between hydraulic unit and ECU. 2) Remove and test motor relay. See HYDRAULIC UNIT RELAYSunder COMPONENT TESTING. If relay is okay, go to next step. Replacerelay if faulty. 3) Check pump motor vehicle ground connection. Ensure vehicleground wire has a clean, tight connection. Repair ground connection ifnecessary. If vehicle ground connection is okay, go to next step. 4) Install motor relay. Turn ignition on. Disconnecthydraulic unit 2-pin connector. Measure voltage between terminal No.51 and vehicle ground. See Fig. 9. If battery voltage is present, goto next step. If battery voltage is not present, repair harnessbetween fusible link and hydraulic unit 2-pin connector. 5) Connect hydraulic unit wiring harness. Disconnect ECU

wiring harness connector. Using ohmmeter, measure resistance betweenECU harness connector terminals No. 5 and 12. See Fig. 3. Resistanceshould be 30-60 ohms. If resistance is not within specification,repair or replace wiring harness between hydraulic unit and ECU. Ifresistance is within specification, go to next step. 6) Using ohmmeter, measure resistance between ECU connectorterminal No. 106 and vehicle ground. Resistance should be .1-.3 ohm.If resistance is not within specification, repair or replace wiringharness between hydraulic unit and ECU. If resistance is withinspecification, replace faulty ECU.

CODE 63 OR 64

If Code 63 or Code 64 is present, replace faulty ECU.

COMPONENT TESTING

ABS POWER RELAY

1) Remove ABS power relay. Relay is located behind radio.Disconnect relay connector. Using ohmmeter, check for continuitybetween terminals No. 1 and 3. See Fig. 10. If continuity exists,replace relay. 2) If continuity does not exist, check for continuity betweenterminals No. 2 and 4. If continuity exists, go to next step. Ifcontinuity does not exist, replace relay. 3) Apply battery voltage to terminal No. 2, and vehicleground terminal No. 4. Check for continuity between terminals No. 1and 3. If continuity exists, relay is okay. If continuity does notexist, replace relay.

Fig. 10: Testing ABS Power RelayCourtesy of Mitsubishi Motor Sales of America.

4WD CONTROL UNIT

Remove radio and remove 4WD control unit. Disconnect controlunit harness connector. Backprobe harness connector. Measure voltagebetween each individual terminal and ground terminal No. 8 (Blackwire). See Figs. 11 and 12. If after all tests have been completedsystem is not operating properly, substitute 4WD control unit withknown good unit and retest.

Fig. 11: Identifying 4WD Control Unit ConnectorCourtesy of Mitsubishi Motor Sales of America.

Fig. 12: 4WD Control Unit Pin Voltage ChartCourtesy of Mitsubishi Motor Sales of America.

4WD INDICATOR SWITCHES

All switches are mounted to transfer case. See Fig. 8.Switches use single harness lead and ground to transfer case. See 4WDINDICATOR SWITCH CONTINUITY CHECK table. Ensure all appropriategrounding straps are connected to vehicle body or frame.

4WD INDICATOR SWITCH CONTINUITY CHECK���������������������������������������������������������������������������������������������������������������������������

Transfer ControlSwitch (1) Lever Position Specification

Center Differential Lock Detection Switch .............. 4H ........ No Continuity 4HLc ......... ContinuityCenter Differential Lock Operation Detection Switch .... 4H ........ No ContinuityOperation Detection Switch ........................ 4HLc ......... Continuity4WD Operation Detection Switch .............. 2H ........ No Continuity 4H ........... ContinuityHI/LO Detection Switch ......... 4HLc ......... Continuity N ........ No Continuity 4LLc ......... Continuity2WD/4WD Detection Switch .............. 2H ........... Continuity 4H ........ No Continuity

(1) - See Fig. 8 for switch location.���������������������������������������������������������������������������������������������������������������������������

HYDRAULIC UNIT RELAYS

Motor Relay 1) Remove motor relay. Using ohmmeter, measure resistancebetween relay terminals No. 85 and 86. See Fig. 13. Resistance shouldbe 30-60 ohms. Check for continuity between relay terminals No. 30 and87. Continuity should not exist. 2) Apply battery voltage to relay terminal No. 85, andvehicle ground terminal No. 86. Check for continuity between terminalsNo. 30 and 87. Continuity should exist. If relay does not test asspecified, replace relay.

Fig. 13: Identifying Motor Relay TerminalsCourtesy of Mitsubishi Motor Sales of America.

Valve Relay 1) Remove valve relay. Using ohmmeter, measure resistance

between relay terminals No. 85 and 86. See Fig. 14. Resistance shouldbe 60-120 ohms. 2) Check for continuity between relay terminals No. 30 and87a. Continuity should exist. Check for continuity between relayterminals No. 30 and 87. Continuity should not exist. 3) Apply battery voltage to relay terminal No. 85, andvehicle ground terminal No. 86. Check for continuity between terminalsNo. 30 and 87. Continuity should exist. Check for continuity betweenterminals No. 30 and 87a. Continuity should not exist. If relay doesnot test as specified, replace relay.

Fig. 14: Identifying Valve Relay TerminalsCourtesy of Mitsubishi Motor Sales of America.

REAR DIFFERENTIAL CONTROL UNIT

Remove rear seat and remove rear differential control unit.Do not disconnect control unit harness connector. Backprobe harnessconnector. Measure voltage between each individual terminal and groundterminal No. 6 (Black wire). See Figs. 15 and 16. If after all testshave been completed system is not operating properly, substitute reardifferential control unit with known good unit and retest.

Fig. 15: Identifying Rear Differential Control Unit ConnectorCourtesy of Mitsubishi Motor Sales of America.

Fig. 16: Rear Differential Control Unit Pin Voltage ChartCourtesy of Mitsubishi Motor Sales of America.

WHEEL SPEED SENSOR

Sensor Resistance Test 1) Before testing sensor resistance, ensure pole piece-to-wheel speed sensor tip is clean. Check wheel sensor pole piece fordamage. If pole piece is damaged, replace sensor. 2) Disconnect sensor connector. Inspect sensor wiring harnessfor broken and pinched wires. Repair or replace harness as necessary.Using ohmmeter, measure sensor resistance at wiring connector. Frontsensor resistance should be 900-1100 ohms. Rear resistance should be1300-2100 ohms. If resistance is not within specification, replacesensor. If resistance is within specification, go to GROUND CIRCUITTEST.

Ground Circuit Test Disconnect wheel speed sensor wiring harness connector.Measure resistance between wheel speed sensor terminals and sensorhousing. Resistance should be more than 100,000 ohms. If resistance isless than specification, replace wheel speed sensor.

REMOVAL & INSTALLATION

ABS POWER RELAY

Removal & Installation ABS power relay is located behind radio. Disconnect negativebattery cable. Remove front center console, located in front of shiftlever. Remove radio. Disconnect relay connector, and remove relay. Toinstall, reverse removal procedure.

ELECTRONIC CONTROL UNIT (ECU)

Removal & Installation 1) ECU is located behind right rear quarter panel trim. SeeFig. 17. Disconnect negative battery cable. Remove quarter panel

mounting screws and trim clip. 2) Carefully remove quarter panel trim. Disconnect ECU wiringharness connector. Remove ECU mounting bolts/nuts and ECU. To install,reverse removal procedure.

Fig. 17: Locating Electronic Control Unit (ECU)Courtesy of Mitsubishi Motor Sales of America.

"G" SENSOR

CAUTION: DO NOT turn "G" sensor upside-down or lay unit on its side. DO NOT drop "G" sensor. DO NOT disassemble unit. Replace "G" sensor as an assembly.

Removal & Installation Sensor is located under center console, near shifter. SeeFig. 18. Remove center console assembly. Disconnect sensor wiringharness connector. Remove sensor. To install, reverse removalprocedure. Tighten bolts to 80 INCH lbs. (12 N.m).

Fig. 18: Locating "G" SensorCourtesy of Mitsubishi Motor Sales of America.

HYDRAULIC UNIT

Removal Remove brakelines from hydraulic unit. Remove relay boxcover. See Fig. 19. Disconnect vehicle ground wire and wiring harnessconnectors from hydraulic unit. Remove hydraulic unit retaining nuts.Carefully remove hydraulic unit.

Installation To install, reverse removal procedure. Install hydraulic unitbrakelines. Ensure brakelines are installed in correct location. Bleedbrake system. See BLEEDING BRAKE SYSTEM.

Fig. 19: Exploded View Of Hydraulic Unit & ComponentsCourtesy of Mitsubishi Motor Sales of America.

WHEEL SPEED SENSOR

Removal & Installation Unplug wheel sensor connector. Remove sensor bolts. Removespeed sensor from vehicle. To install, reverse removal procedure.Sensors are not interchangeable. Adjust wheel speed sensor-to-rotorgap. See WHEEL SPEED SENSOR under ADJUSTMENTS. To completeinstallation, reverse removal procedure.

WHEEL SENSOR ROTOR

Removal & Installation Remove brake disc. Remove disc assembly. Remove wheelbearings. Remove axle hub. Remove bolts attaching sensor rotor to hubassembly. To install, reverse removal procedure.

OVERHAUL

HYDRAULIC UNIT

DO NOT attempt to overhaul or disassemble hydraulic unit. Ifhydraulic unit is defective, replace entire assembly.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS TABLE�����������������������������������������������������������������������������������������������������������������������

Application INCH Lbs. (N.m)

"G" Sensor Mounting Bolt ........................ 80 (12)Wheel Speed Sensor Bolt .................... 84-120 (9-14)�����������������������������������������������������������������������������������������������������������������������

WIRING DIAGRAM

Fig. 20: Anti-Lock Brake System (ABS) Wiring Diagram