4WD MITSUBISHI MONTERO 1998 Service Manual

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

DVOM, check voltage between ECU 22-pin connector terminal No. 35 and
ground. See Figs. 5-6. Battery voltage should exist in 4WD. Go to next
step.
3) If voltage is not as specified, check and repair
connectors and wiring harness between center differential lock
detection switch and ECU. See WIRING DIAGRAMS. Center differential
lock detection switch is located on side of transfer case. See Fig. 9.
If voltage is as specified, check and repair ECU 22-pin connector. If
connector is okay, replace ECU.
Fig. 9: Identifying 4WD Indicator Switch Location
Courtesy of Mitsubishi Motor Sales of America.
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 no indicator lights come on, repair 4WD indicator power
circuit, or check for faulty 4WD indicator control unit. See 4WD
CONTROL UNIT under COMPONENT TESTS. If center differential light comes
on, regardless of position of transfer shift lever, check the
following:

* 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

NOTE: DTC is set if valve relay is removed or if no power is
supplied to relay.
1) Inspect ABS relay box. See Fig. 3. Replace ABS relay box
if needed. If ABS relay box is okay, go to next step.
2) Disconnect ABS relay box 8-pin connector. Turn ignition
on. Using a DVOM, check voltage between ABS relay box 8-pin harness
connector terminal No. 6 and ground. See Fig. 4. If battery voltage
exists, go to next step. If battery voltage does not exist, check and
repair wiring harness between ABS valve relay and fusible link No. 1.
See WIRING DIAGRAMS .
3) Disconnect ECU connectors. Check resistance between ECU
22-pin connector terminal No. 37 and ECU 26-pin connector terminal No.
26. Resistance should be 60-120 ohms. If resistance is as specified,
go to next step. If resistance is not as specified, check and repair
connectors and related wiring harness between ABS valve relay and ECU.
See WIRING DIAGRAMS .
4) Check continuity between ECU 22-pin connector terminal No.
48 and ground. If continuity exists, go to next step. If continuity
does not exist, check and repair wiring harness between ABS valve
relay and ECU. See WIRING DIAGRAMS.
5) Check and repair ECU 22-pin connector. If connector is
okay, replace ECU.
DTC 53: MOTOR RELAY
NOTE: DTC is set when ECU detects motor relay on but motor does
not run, motor relay off but motor does not stop, or when
motor relay is faulty.
1) Using scan tool, perform hydraulic unit actuator test. If
motor is not operating, go to next step. If motor is still operating,
repair wiring harness between hydraulic unit and ECU. See
WIRING DIAGRAMS .
2) Inspect ABS relay box. See Fig. 3. Replace ABS relay box
if needed. If ABS relay box is okay, go to next step.
3) Disconnect ABS relay box 2-pin connector. Using DVOM,
check voltage between 2-pin connector terminal No. 11 and ground. See
Fig. 4 . If battery voltage is present, go to next step. If battery
volt age is not present, check and repair wiring harness between ABS
motor relay and fusible link No. 1. See WIRING DIAGRAMS.
4) Turn ignition off. Disconnect ECU connectors. Check
resistance between ECU 22-pin connector terminal No. 38 and 26-pin
connector terminal No. 26. Resistance should be 26-38 ohms. If
resistance is as specified, go to next step. If resistance is not as
specified, check and repair connectors and related wiring harness
between ABS motor and ECU. See WIRING DIAGRAMS.
5) Check resistance between ECU 22-pin connector terminal No.
49 and ground. Resistance should be 0.1-0.3 ohm. If resistance is as
specified, go to next step. If resistance is not as specified, check
and repair hydraulic unit motor ground connection or wiring harness
between ECU and hydraulic unit. See WIRING DIAGRAMS.
6) Check motor operation. Momentarily apply battery voltage
to hydraulic unit connector terminal No. 11. See Fig. 11. If motor
operates, go to next step. If motor does not operate, replace
hydraulic unit.
7) Check and repair ECU 22-pin connector. If connector is
okay, replace ECU.
COMPONENT TESTS
4WD CONTROL UNIT

Remove radio and remove 4WD control unit. Disconnect control
unit harness connector. Backprobe harness connector. Check voltage
between each individual terminal and ground terminal No. 8 (Black
wire). See Figs. 12 and 13. If after all tests have been completed
system is not operating properly, substitute 4WD control unit with
known-good unit and retest.
Fig. 12: Identifying 4WD Control Unit Connector
Courtesy of Mitsubishi Motor Sales of America.
Fig. 13: 4WD Control Unit Pin Voltage Chart
Courtesy of Mitsubishi Motor Sales of America.
4WD INDICATOR SWITCHES

All switches are mounted to transfer case. See Fig. 9.
Switches use single harness lead and ground to transfer case. See 4WD
INDICATOR SWITCH CONTINUITY CHECK table. Ensure all appropriate
grounding straps are connected to vehicle body or frame.
4WD INDICATOR SWITCH CONTINUITY CHECK









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Switch Transfer Control Lever Position Specification
Center Differential Lock
Detection Switch .............. 4H ................. No Continuity
Detection Switch ............. 4HLc ................... Continuity
Center Differential Lock
Operation Detection Switch .. 4H .................. No Continuity
" ........................... 4HLc .................... Continuity
4WD Operation
Detection Switch .............. 2H ................. No Continuity
Detection Switch .............. 4H .................... Continuity
HI/LO Detection Switch ...... 4HLc .................... Continuity
" ............................. N .................. No Continuity
" ........................... 4LLc .................... Continuity
2WD/4WD
Detection Switch ............ 2H .................... Continuity
" ........................... 4H ................. No Continuity









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REAR DIFFERENTIAL CONTROL UNIT
Remove rear seat and remove rear differential control unit.
Do not disconnect control unit harness connector. Backprobe harness
connector. Check voltage between each individual terminal and ground
terminal No. 6 (Black wire). See Figs. 14 and 15. If after all tests
have been completed system is not operating properly, substitute rear
differential control unit with known good-unit and retest.
Fig. 14: Identifying Rear Differential Control Unit Connector
Courtesy of Mitsubishi Motor Sales of America.

AUTO TRANS DIAGNOSIS - R4AW3 & V4AW3
1998 Mitsubishi Montero
1997-98 AUTOMATIC TRANSMISSIONS
Mitsubishi R4AW3 & V4AW3 Electronic Controls
Montero, Montero Sport
APPLICATION
TRANSMISSION APPLICATION








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Vehicle Transmission Model
Montero Sport 2WD ............................................ R4AW3
Montero & Montero Sport 4WD .................................. V4AW3









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CAUTION: Vehicle is equipped with Supplemental Restraint System (SRS).
When servicing vehicle, use care to avoid accidental air bag
deployment. SRS-related components are located in steering
column, center console, instrument panel and lower panel on
instrument panel. DO NOT use electrical test equipment on
these circuits. If necessary, deactivate SRS before servicing
components. See AIR BAG SERVICING article in APPLICATIONS &
IDENTIFICATION.
DESCRIPTION
Automatic transmission is a 4-speed electronically controlled
transmission. Solenoids that control shift changes are located in
valve body. Solenoids are controlled by a Transmission Control Module
(TCM). TCM receives information from various input devices and uses
this information to control shift solenoids for transmission shifting
and lock-up solenoid for torque converter lock-up.
An Overdrive (OD) switch is mounted on the shift lever. 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 illuminate.
A pattern select switch is located near shift lever on center
console. Pattern select switch contains a NORMAL and a HOLD operating
position. When pattern select switch is depressed (HOLD position) with\
shift lever in Drive position, transmission starts in 2nd gear.
Upshifts and downshifts will occur at a higher vehicle speed than with
switch in NORMAL position. See MITSUBISHI R4AW3 & V4AW3 OVERHAUL
article. Indicator light on instrument panel indicates pattern select
switch is in HOLD position.
Transmission is equipped with a shift lock and key interlock
system. Shift lock system prevents shift lever from being moved from
Park unless brake pedal is depressed. Key interlock system prevents
ignition key from being moved from ACC to LOCK position on ignition
switch unless shift lever is in Park. See MITSUBISHI SHIFT LOCK
SYSTEMS article.
OPERATION
TCM
TCM receives information from various input devices and uses

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

when transfer case is in 4WD low-lock range.
Fig. 1: Locating Transmission Control Module (Montero)
Courtesy of Mitsubishi Motor Sales of America.
Fig. 2: Locating Transmission Control Module (Montero Sport)
Courtesy of Mitsubishi Motor Sales of America.
TCM OUTPUT DEVICES

If DTC 51 is set also, go to DTC 51: 1ST GEAR RATIO SIGNAL
INCORRECT test. If DTC 51 is not set, check overdrive brake for a
mechanical failure. See OVERDRIVE BRAKE in MITSUBISHI R4AW3 & V4AW3
OVERHAUL article.
SYMPTOM TROUBLE SHOOTING
NOTE: Check system using appropriate scan tool. See WIRING DIAGRAMS
for electrical schematics and COMPONENT TESTING.
COMMUNICATION WITH SCAN TOOL NOT POSSIBLE
If scan tool cannot communicate with TCM, check proper
connection with DLC. Check TCM power circuits, TCM ground circuits and
malfunctioning TCM.
SHIFT POINTS INCORRECT
If shift points are incorrect, check for DTCs. If no DTC is
present, check oil temperature sensor, pattern select switch, 4WD low
range detection switch and TCM for proper operation.
UPSHIFTS OCCUR SPONTANEOUSLY
If upshifting occurs spontaneously, check park/neutral
position switch, overdrive switch and TCM for proper operation.
TCC LOCK-UP MALFUNCTIONING
If TCC lock-up system is not operating properly, check torque
converter, valve body, lock-up switch and oil temperature switch.
COMPONENT TESTING
A/T FLUID TEMPERATURE SWITCH
1) Remove fluid temperature switch, located to rear of
neutral safety switch. Immerse switch in container of ATF up to top
threaded portion of switch. Using a DVOM, check continuity between
switch terminals. Continuity should not exist when fluid temperature
is 257
F (125C) or less.
2) When fluid is heated to 289-304F (143-151C), continuity
should exist. Replace switch if necessary. Apply thread sealant to
fluid temperature switch threads and install in transmission.
BRAKELIGHT SWITCH
1) Disconnect electrical connector from brakelight switch,
located near brake pedal. Using ohmmeter, ensure continuity exists
between terminal No. 2 (White/Red wire) and terminal No. 3 (Green
wire) with brake pedal released. Replace brakelight switch if
continuity does not exist. Continuity should not exist between
terminals No. 2 and No. 3 with brake pedal depressed.
2) If continuity does not exist, ensure brake pedal is
properly adjusted so brakelight switch has proper travel for switch
operation. If proper brakelight switch travel exists, replace
brakelight switch.
ENGINE COOLANT TEMPERATURE (ECT) SENSOR