1998 MITSUBISHI MONTERO engine

Fig. 2: Identifying Instrument Cluster Connector Terminals
Courtesy of Mitsubishi Motor Sales of America.
After Engine Starts, ANTI-LOCK Warning Light Remains On
1) With ignition on, disconnect instrument cluster
connectors. If warning light remains on, replace instrument cluster.
If warning light goes off, go to next step.
2) Disconnect ECU 22-pin connector and ABS relay box 8-pin
connector. See Fig. 3. If warning light goes off, replace ECU. If
warning light stays on, check and repair connectors and related wiring
harness between ECU, instrument cluster, and ABS valve relay. See
WIRING DIAGRAMS .
Fig. 3: Exploded View Of Hydraulic Unit & Components
Courtesy of Mitsubishi Motor Sales of America.
Ignition Switch In START Position, ANTI-LOCK Warning Light
Inoperative

7) Inspect condition of toothed rotor. Check for broken or
deformed teeth. If toothed rotor is okay, go to next step.
8) Check ECU connectors. Repair connectors as needed. If
connectors are okay, replace ECU.
DTC 15: WHEEL SPEED SENSOR OUTPUT SIGNAL (ABNORMAL)
NOTE: DTC will set if ECU detects a wheel speed sensor fault other
than an open or short circuit.
1) Ensure sensor is properly installed. See WHEEL SPEED
SENSOR (WSS) under REMOVAL & INSTALLATION . Correct installation if
needed. If installation is okay, go to next step.
2) Raise and support vehicle. Disconnect ECU connectors.
Using DVOM, backprobe specified ECU connector terminals. See
WHEEL SPEED SENSOR OUTPUT CIRCUIT IDENTIFICATION table. See Figs. 5-6.
Check voltage between each harness connector terminal while rotating
wheel at 1/2 to one rotation per second. If pulse voltage is 70 mV or
more, go to step 7). If voltage is not as specified, go to next step.
3) Inspect condition of suspect speed sensor. Ensure tip of
speed sensor is clean. If speed sensor is okay, go to next step.
4) Disconnect sensor connector. Using DVOM, check resistance
across sensor terminals. Resistance for front sensors should be 1170-
1350 ohms. Resistance for rear sensors should be 1300-1500 ohms. If
resistance is as specified, go to next step. If resistance is not as
specified, replace sensor.
5) Remove sensor. Check resistance between each sensor
terminal and sensor body. If resistance is 100,000 ohms or more, go to
next step. If resistance is not as specified, replace sensor.
6) Inspect condition of toothed rotor. Check for broken or
deformed teeth. If toothed rotor is okay, go to next step.
7) Check ECU connectors. Repair connectors as needed. If
connectors are okay, replace ECU.
DTC 16: ECU POWER SUPPLY
NOTE: DTC will set if ECU power supply voltage is not within
standard value. If voltage returns to normal, DTC will be
erased. Ensure battery is fully charged.
1) Ensure battery voltage is 10-17 volts. Turn ignition off.
Disconnect ECU 26-pin connector. Start engine. Using DVOM, check
voltage between ECU 26-pin connector terminal No. 13 and ground. See
Figs. 5 -6. If battery voltage exists, go to step 3). If battery
voltage do es not exist, go to next step.
2) Check and repair connectors and related wiring between
ignition switch and ECU. See WIRING DIAGRAMS. If connectors and wiring
are okay, check and repair battery or charging system.
3) Check voltage between ECU 26-pin connector terminal No. 26
and ground. If battery voltage exists, go to next step. If battery
voltage does not exist, check and repair connectors and wiring harness
between fusible link and ECU. See WIRING DIAGRAMS.
4) Check and repair ECU connectors. If connectors are okay,
replace ECU.
DTC 21, 22, 23 OR 24: WHEEL SPEED SENSOR (ABNORMAL)
NOTE: DTC sets if wheel speed sensor does not output a signal when
driving, and an open circuit cannot be found.
1) Ensure sensor is properly installed. See WHEEL SPEED
SENSOR (WSS) under REMOVAL & INSTALLATION . Correct installation if
needed. If installation is okay, go to next step.

2) Disconnect ECU 26-pin connector. Check resistance between
specified ECU connector terminals. See
WHEEL SPEED SENSOR OUTPUT CIRCUIT IDENTIFICATION table. See Figs. 5-6.
Resistance for front sensors should be 1170-1350 ohms. Resistance for
rear sensors should be 1300-1500 ohms. If resistance is as specified,
go to next step. If resistance is not as specified, check and repair
connectors and related wiring between ECU and suspect sensor. See
WIRING DIAGRAMS .
3) Raise and support vehicle. Disconnect ECU connectors.
Using DVOM, backprobe specified ECU connector terminals. See
WHEEL SPEED SENSOR OUTPUT CIRCUIT IDENTIFICATION table. See Figs. 5-6.
Check voltage between each harness connector terminal while rotating
wheel at 1/2 to one rotation per second. If pulse voltage is 70 mV or
more, go to step 8). If voltage is not as specified, go to next step.
4) Inspect condition of suspect speed sensor. Ensure tip of
speed sensor is clean. If speed sensor is okay, go to next step.
5) Disconnect sensor connector. Using DVOM, check resistance
across sensor terminals. Resistance for front sensors should be 1170-
1350 ohms. Resistance for rear sensors should be 1300-1500 ohms. If
resistance is as specified, go to next step. If resistance is not as
specified, replace sensor.
6) Remove sensor. Check resistance between each sensor
terminal and sensor body. If resistance is 100,000 ohms or more, go to
next step. If resistance is not as specified, replace sensor.
7) Inspect condition of toothed rotor. Check for broken or
deformed teeth. If toothed rotor is okay, go to next step.
8) Check ECU connectors. Repair connectors as needed. If
connectors are okay, replace ECU.
DTC 25: FREE WHEEL ENGAGE SWITCH
NOTE: DTC sets if ECU detects an open circuit in free wheel engage
switch.
1) Start engine. Ensure 4WD indicator light operates
correctly when transfer shift lever is moved to desired 4WD positions.
If indicator light operates correctly, go to step 3). If indicator
light does not operate correctly, go to next step.
2) Turn engine off. Check wiring harness between 4WD
indicator control unit (located behind radio) and free wheel engage
switch (located on right side of front differential housing, near
carrier assembly). If circuit is okay, replace 4WD indicator control
unit.
3) Disconnect ECU 22-pin connector. Turn ignition on. Using
DVOM, check voltage between ECU 22-pin connector terminal No. 45 and
ground. See Figs. 5-6. In 2WD, battery voltage should exist. Battery
voltage should not exist in 4WD. If voltage is as specified, go to
next step. If voltage is not as specified, check and repair connectors
and wiring harness between free wheel engage switch and ECU. See
WIRING DIAGRAMS .
4) Check and repair ECU 22-pin connector. If connector is
okay, replace ECU.
DTC 26: CENTER DIFFERENTIAL LOCK DETECTION SWITCH
NOTE: DTC sets if ECU detects an open circuit in center
differential lock detection switch system.
1) Start engine. Ensure 4WD indicator light operates
correctly when transfer shift lever is moved to desired 4WD positions.
If indicator light does not operate correctly, go to step 4). If
indicator light operates correctly, go to next step.
2) Disconnect ECU 22-pin connector. Turn ignition on. Using

* 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. See
WIRING DIAGRAMS .
5) If 4WD indicator light does not come on with transfer
shift lever in "4H" position, repair wiring harness between 4WD
indicator control unit and center differential lock switch. Check for
faulty 4WD indicator control unit.
6) If 4WD indicator light does not come on with transfer
shift lever in "4H" position, repair wiring harness between 4WD
indicator control unit and free wheel engage switch. See
WIRING DIAGRAMS . Check ground wire at engage switch. Check for faulty
free wheel engage switch.
DTC 27: REAR DIFFERENTIAL LOCK DETECTION SWITCH (WITH
DIFFERENTIAL LOCK)
NOTE: DTC is set if ECU detects an open circuit in rear
differential lock detection switch system.
1) Start engine. Ensure rear differential indicator light
comes on when top of rear differential lock switch (located below
radio) is pushed. If indicator light comes on, go to step 3). If
indicator light does not come on, go to next step.
2) Turn engine off. Check wiring harness between rear
differential lock control unit and rear differential lock switch. See
WIRING DIAGRAMS . Check rear differential lock control unit power
circuit. See REAR DIFFERENTIAL CONTROL UNIT under COMPONENT TESTS. If
circuit is okay, replace rear differential lock control unit.
3) Disconnect ECU 22-pin connector. Turn ignition on. Using
DVOM, check voltage between terminal No. 46 and ground. See Figs. 5-6.
When rear differential is locked, battery voltage should not be
present. When rear differential is unlocked, battery voltage should be
present. If voltage is as specified, go to next step. If voltage is
not as specified, repair connectors and related wiring harness between
ECU and rear differential lock switch. See WIRING DIAGRAMS.
4) Check and repair ECU 22-pin connector. If connector is
okay, replace ECU.
DTC 27: REAR DIFFERENTIAL LOCK DETECTION SWITCH (WITHOUT
DIFFERENTIAL LOCK)
NOTE: DTC is set if ECU detects an interruption of battery voltage
at ECU terminal No. 46.
1) Check fuse No. 18 in main fuse block. If fuse is blown,
correct cause of blown fuse, and replace fuse. If fuse is okay, go to
next step.
2) Disconnect ECU 22-pin connector. Turn ignition on. Using
DVOM, check voltage between terminal No. 46 and ground. See Figs. 5-6.
If battery voltage is present, go to next step. If battery voltage is
not present, check and repair connectors and related wiring harness
between ECU and fuse No. 18. See WIRING DIAGRAMS.
3) Check and repair ECU 22-pin connector. If connector is
okay, replace ECU.
DTC 32: "G" SENSOR SYSTEM
NOTE: DTC is set if ECU detects "G" sensor output voltage less

this information to control solenoids on transmission valve body. TCM
controls transmission shifting and torque converter lock-up.
TCM contains a self-diagnostic system, which will store
Diagnostic Trouble Codes (DTC) if failure or problem exists in
electronic control system. DTC can be retrieved to determine problem
area. See SELF-DIAGNOSTIC SYSTEM. TCM is located under left side of
instrument panel, left of steering column. See Fig. 1.
TCM INPUT DEVICES
Brakelight Switch Signal
Brakelight switch delivers input signal to TCM, indicating
vehicle braking. Brakelight switch is located on brake pedal support.
Cruise Control Electronic Control Unit (ECU)
Cruise control ECU delivers an input signal to control
overdrive operation in accordance with vehicle speed when cruise
control is operating. When in overdrive with cruise control on, if
vehicle speed drops 2 MPH less than the set speed, overdrive is
released to prevent reduction in vehicle speed. Once vehicle speed is
more than the set speed, overdrive function is resumed. If coolant
temperature is low, transmission will not shift into overdrive. Cruise
control ECU is located below center A/C vent, behind temperature
control panel on Montero. On Montero Sport, cruise control ECU is
located behind driver's kick panel.
Engine Coolant Temperature Sensor (ECT) Signal
Engine coolant temperature sensor delivers input signal to
TCM, indicating engine coolant temperature. Coolant temperature sensor
is located on engine.
Input & Output Shaft Speed Sensors
Sensors are magnetic pick-ups that monitor input and output
shaft speeds. AC waveforms are input to TCM by sensors. Sensors are
located on front and rear side of transmission case.
OD Switch Signal
The OD switch provides an input signal to TCM to indicate
when overdrive is selected by operator. When OD switch is depressed to
ON position, transmission will shift into 4th gear when shift lever is
in "D" position, and OD OFF light on instrument panel will go off.
When OD switch is released to OFF position, transmission will shift
into 3rd gear, and OD OFF light on instrument panel will come on. The
OD switch is mounted on shift lever.
Oil Temperature Sensor Signal
Oil temperature sensor provides TCM with ATF temperature
values. TCM uses this information to control shift points for maximum
performance. If transmission oil temperature exceeds standard values,
instrument panel ATF - TEMP light will come on. Sensor is mounted to
cooler line at transmission.
Park/Neutral Position (PNP) Switch Signal
PNP switch delivers an input signal to TCM indicating shift
lever position. Switch is located on side of transmission.
Throttle Position (TP) Sensor Signal
TP sensor delivers closed throttle and variable throttle
position input signals to TCM. TP sensor is located on side of
throttle body.
4WD Low Range Detection Switch
4WD low range detection switch provides information to TCM

Fig. 4: Checking Operation Of Shift Solenoids No. 1 & No. 2
Courtesy of Mitsubishi Motor Sales of America.
SELF-DIAGNOSTIC SYSTEM
SYSTEM DIAGNOSIS
NOTE: Before testing transmission, ensure fluid level is correct
and throttle and shift cables are properly adjusted. Ensure
engine starts with shift lever in Park and Neutral to ensure
proper adjustment of park/neutral position switch.
Transmission must first be tested by checking for stored
codes. See RETRIEVING DIAGNOSTIC TROUBLE CODES (DTC).
TCM monitors transmission operation and contains a self-
diagnostic system which stores a DTC if an electronic control system
failure or problem exists. If a problem exists in any of the solenoids
or speed sensors and a DTC is set, TCM delivers a signal to blink the
ATF TEMP light on instrument panel to warn the driver. DTC may be set
if a failure exists and can be retrieved for transmission diagnosis.
RETRIEVING DIAGNOSTIC TROUBLE CODES (DTC)
NOTE: Before retrieving DTC, ensure proper battery voltage exists
for proper self-diagnosis system operation. DO NOT disconnect
battery or ECM connectors before retrieving DTC.
Retrieving Codes Using Scan Tool
Ensure ignition switch is in OFF position. Connect scan tool
to Data Link Connector (DLC). See Fig. 5. Turn ignition switch to ON
position. Check for stored DTC and record code(s). See DIAGNOSTIC
TROUBLE CODE IDENTIFICATION table.

Once repairs have been performed, DTCs must be cleared from
TCM memory. DTCs may be cleared by disconnecting negative battery
cable for 10 seconds or more. Reconnect cable and ensure DTCs have
been cleared. Start engine and warm to normal operating temperature.
Run engine at idle for 10 minutes. DTCs may also be cleared using scan
tool. Refer to manufacturer's instruction manual.
DIAGNOSTIC TESTS
NOTE: For terminal and wire color identification, see WIRING
DIAGRAMS.
DTC 11: THROTTLE POSITION (TP) SENSOR
For diagnosis and testing information, see appropriate SELF-
DIAGNOSTICS article in ENGINE PERFORMANCE section. If TP sensor is
okay, check wiring harness and connectors between TP sensor and TCM.
Repair if necessary. If wiring harness and connectors are okay,
replace TCM.
DTC 15 & 16: OPEN OR SHORT IN OIL TEMPERATURE SENSOR CIRCUIT
1) Test oil temperature for proper operation. See OIL
TEMPERATURE SENSOR under COMPONENT TESTING. If oil temperature sensor
is okay, check wire harness, connectors and ground circuit for poor
connections or damage. Go to next step.
2) If wire harness and connectors are okay, check DTCs again
and verify code No. 15 or No. 16 still exists. If either code still
exists, replace TCM.
DTC 21 & 22: SHORT OR OPEN IN IGNITION SIGNAL CIRCUIT
1) Using an external tachometer, verify vehicles' tachometer
is operating accurately. If tachometer is incorrect, check ignition
coil and ignition power transistor and circuits for malfunction. See
appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE section.
2) If tachometer is okay, check TCM wire harness connector
for poor connection. If wire harness is okay, recheck DTCs. If codes
reappear check wire harness between ignition power transistor and TCM.
If wire harness is okay, replace TCM.
DTC 23 & 24: OPEN OR SHORT IN SIGNAL LINE (ECT) FROM ECM TO
TCM
Check wire harness, connectors and ground circuit for poor
connections or damage. Go to next step. If wire harness and connectors
are okay, check DTCs again and verify code No. 23 or No. 24 still
exists. If either code still exists, replace TCM.
DTC 29 & 30: SHORT OR OPEN IN PARK/NEUTRAL POSITION (PNP)
SWITCH CIRCUIT
1) Check PNP switch for correct operation. See. If PNP switch
is okay, disconnect switch connector and measure voltage between
harness connector terminal No. 1 and ground.
2) If battery voltage does not exist, check wire harness and
connectors. See WIRING DIAGRAMS. If battery voltage exists, check wire
harness and connectors between PNP switch and TCM. If wire harness is
okay, replace TCM.
DTC 31: INPUT SPEED SENSOR

1) Check input speed sensor. See INPUT SPEED SENSOR under
COMPONENT TESTING. If resistance is as specified, reconnect speed
sensor connector and go to next step. If resistance is not as
specified replace input speed sensor and recheck DTCs.
2) Connect voltmeter between solenoid and sensor connector
terminals No. 9 and No. 10. See Fig. 9. Lift and support vehicle to
allow drive wheels to spin freely. With transmission in "D" position,
engine at 1000 RPM and wheel speed at 19 MPH (30 km/h). Measured
voltage should be .3-2.5 volts.
3) If voltage is as specified, go to next step. If voltage is
not as specified, replace input speed sensor. If DTC still exists,
check speed sensor rotor. See MITSUBISHI R4AW3 & V4AW3 OVERHAUL
article. If DTC still exists after speed sensor rotor is replaced,
check for noise interference and repair.
4) Check and repair wiring harness and connectors between
input speed sensor and TCM. If wiring is okay, recheck DTC. If DTC
still exists, replace TCM.
Fig. 9: Identifying Sensor & Solenoid Connector Terminals
Courtesy of Mitsubishi Motor Sales of America.
DTC 32: OUTPUT SPEED SENSOR
1) Check output speed sensor. See OUTPUT SPEED SENSOR under
COMPONENT TESTING. If resistance is as specified, reconnect speed
sensor connector and go to next step. If resistance is not as
specified replace output speed sensor and recheck DTCs.
2) Connect voltmeter between solenoid and sensor connector
terminals No. 3 and No. 4. See Fig. 9. Lift and support vehicle to
allow drive wheels to spin freely. With transmission in "D" position,
engine at 1000 RPM and wheel speed at 19 MPH (30 km/h). Measured