1998 MITSUBISHI MONTERO sensor

for one second, and then go out. Turn ignition switch to START
position. Warning light should come on and stay on.
2) When ignition switch is turned from START to ON position,
warning light should come on for one second, and then go out. If
warning light functions as specified, go to step 3). If warning light
does not function as specified, see appropriate trouble shooting test:
* IGNITION SWITCH IN ON POSITION (ENGINE NOT RUNNING),
ANTI-LOCK WARNING LIGHT INOPERATIVE
* AFTER ENGINE STARTS, ANTI-LOCK WARNING LIGHT REMAINS ON
* IGNITION SWITCH IN START POSITION, ANTI-LOCK WARNING LIGHT
INOPERATIVE
* IGNITION SWITCH IN ON POSITION, ANTI-LOCK WARNING LIGHT
BLINKS TWICE. IN START POSITION, LIGHT STAYS ON. WHEN
IGNITION SWITCH IS CYCLED FROM START TO ON POSITION, LIGHT
BLINKS ONCE, THEN TURNS OFF
3) Test drive vehicle. If ANTI-LOCK warning light does not
come on at low speed, go to next step. If light comes on at low speed,
motor relay, solenoid valve or Wheel Speed Sensor (WSS) malfunction is\
indicated. Go to step 6). If insufficient braking force or ABS
malfunction exists, go to next step. If none of listed symptoms exist,
go to step 6).
4) Check conventional brake system components for proper
operation. Check for mechanical lock of hydraulic unit solenoid valve.
Check for plugged hydraulic line in hydraulic unit. Repair or replace
as necessary. If hydraulic unit is okay, go to next step.
5) Ensure WSS rotor gap is correct. See WHEEL SPEED SENSOR
(WSS) under ADJUSTMENTS. Check for faulty wheel speed sensor. See
WHEEL SPEED SENSOR (WSS) under COMPONENT TESTS. Replace sensor as
necessary. See WHEEL SPEED SENSOR (WSS) under REMOVAL & INSTALLATION.
Inspect ECU connectors and related wiring harness. See WIRING DIAGRAMS
. If testing indicates no mechanical or electrical failures,
substitute ECU with known-good unit and retest.
6) Enter ABS self-diagnostics and retrieve Diagnostic Trouble
Codes (DTCs). See RETRIEVING DTCs under SELF-DIAGNOSTIC SYSTEM. If no
DTCs are displayed, fault may be intermittent. Attempt to make
malfunction reoccur. If no diagnostic output exists, check and repair
wiring harness between ECU and data link connector. See
WIRING DIAGRAMS .
NOTE: Trouble shoot ANTI-LOCK warning light in following sequence:
instrument cluster circuit, ECU and valve relay.
Ignition Switch In ON position (Engine Not Running),
ANTI-LOCK Warning Light Inoperative
1) If all other warning lights come on with ignition on, go
to step 3). If other warning lights do not come on, check fuse No. 11
in main fuse panel. If fuse is blown, correct cause of blown fuse, and
replace fuse. If fuse is okay, go to next step.
2) Remove instrument cluster. Turn ignition on. Using DVOM,
check voltage between vehicle ground and instrument cluster ANTI-LOCK
warning light terminal No. 28. See Fig. 2. If light does not come on,
go to next step. If light comes on, check and repair connectors and
related wiring harness between instrument cluster, ABS valve relay and
ECU. See WIRING DIAGRAMS .
3) Turn ignition off. Check for faulty warning light bulb.
Replace bulb as necessary. If bulb is okay, check and repair
connectors and related wiring harness between instrument cluster and
ECU. See WIRING DIAGRAMS . If connectors and wiring are okay, replace
instrument cluster.

Fig. 8: Identifying Data Link Connector Terminals
Courtesy of Mitsubishi Motor Sales of America.
CLEARING DTCs
To clear DTCs using scan tool, follow scan tool
manufacturer's instructions. To clear DTCs without scan tool,
disconnect negative battery cable for at least 10 seconds. Reconnect
battery cable and repeat RETRIEVING DTCs to confirm that malfunction
has been corrected.
DTC DEFINITION









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DTC ( 1) System Affected
11 ..................... Right Front Wheel Speed Sensor (Open/Short)\
12 ...................... Left Front Wheel Speed Sensor (Open/Short)\
13 ...................... Right Rear Wheel Speed Sensor (Open/Short)\
14 ....................... Left Rear Wheel Speed Sensor (Open/Short)\
15 ..................... Wheel Speed Sensor Output Signal (Abnormal)\
16 ................................................ ECU Power Supply
21 ....................... Right Front Wheel Speed Sensor (Abnormal)\
22 .............................. Left Front Wheel Sensor (Abnormal)\
23 ........................ Right Rear Wheel Speed Sensor (Abnormal)\
24 ......................... Left Rear Wheel Speed Sensor (Abnormal)\
25 ........................................ Free Wheel Engage Switch
26 ....................... Center Differential Lock Detection Switch
27 ..................... ( 2) Rear Differential Lock Detection Switch

27 ..................... (3) Rear Differential Lock Detection Switch
32 ............................................... "G" Sensor System
33 ......................................... Stoplight Switch System
41 ....................................... RF Solenoid Valve Circuit
42 ....................................... LF Solenoid Valve Circuit
43 ..................................... Rear Solenoid Valve Circuit
51 ..................................................... Valve Relay
53 ..................................................... Motor Relay
63 Or 64 ............................................ ( 4) Faulty ECU
( 1) - See appropriate DTC under DIAGNOSTIC TESTS.
( 2) - Vehicles with differential lock.
( 3) - Vehicles without differential lock.
( 4) - Replace ECU.









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DIAGNOSTIC TESTS
DTC 11, 12, 13 OR 14: WHEEL SPEED SENSOR (OPEN/SHORT
CIRCUIT)
NOTE: DTC will set if ECU detects a wheel speed sensor 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) 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 .
WHEEL SPEED SENSOR OUTPUT CIRCUIT IDENTIFICATION









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Application Terminals No.
Left Front .................................................. 7 & 20
Left Rear ................................................... 9 & 22
Right Front ................................................ 10 & 23
Right Rear .................................................. 8 & 21









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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 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

than 0.5 volt or more than 4.5 volts, or an open or short
circuit in "G" sensor system.
1) Disconnect "G" sensor connector. Sensor is located on
bracket under center console, next to shifter. See Fig. 10. Connect
Special Tool (MB991348) between sensor and connector. Using a DVOM,
check voltage between sensor connector terminals No. 2 (Blue/White
wire) and No. 3 (Black/Red wire). Voltage should be 2.38-2.62 volts.
If voltage is as specified, reconnect sensor connector and go to step
3). If voltage is not as specified, leave special tool and DVOM
connected and go to next step.
2) Note top center position of sensor, and remove sensor. See
"G" SENSOR under REMOVAL & INSTALLATION . Secure sensor so that arrow
on sensor is facing straight down. Voltage should be 3.4-3.6 volts. If
voltage is specified, reinstall sensor and go to next step. If voltage
is not as specified, replace sensor.
3) Turn ignition off. Disconnect ECU 26-pin connector. Turn
ignition on. Check voltage between ECU 26-pin connector terminals No.
4 and 17. See Figs. 5-6. Voltage should be 2.4-2.6 volts. If voltage
is as specified, go to next step. If voltage is not as specified,
check and repair connectors and related wiring harness between ECU and
sensor. See WIRING DIAGRAMS .
4) Check and repair ECU 26-pin connector. If connector is
okay, replace ECU.
Fig. 10: Locating "G" Sensor
Courtesy of Mitsubishi Motor Sales of America.
DTC 33: STOPLIGHT SWITCH SYSTEM

Fig. 15: Rear Differential Control Unit Pin Voltage Chart
Courtesy of Mitsubishi Motor Sales of America.
WHEEL SPEED SENSOR (WSS)
WSS Resistance Test
1) Before testing WSS resistance, ensure pole piece-to-WSS
tip is clean. Check WSS pole piece for damage. If pole piece is
damaged, replace WSS.
2) Disconnect WSS connector. Inspect WSS wiring harness for
broken and pinched wires. See WIRING DIAGRAMS. Repair harness as
necessary. If harness is okay, go to next step.
3) Using ohmmeter, check resistance across WSS terminals.
Resistance for front WSS should be 1170-1350 ohms. Resistance for rear
WSS should be 1300-1500 ohms. If resistance is as specified, go to
GROUND CIRCUIT TEST. If resistance is not as specified, replace WSS.
Ground Circuit Test
Disconnect WSS wiring harness connector. Check resistance
between each WSS terminal and WSS housing. Resistance should be more
than 100,000 ohms. If resistance is not as specified, replace WSS.
REMOVAL & INSTALLATION
ELECTRONIC CONTROL UNIT (ECU)
Removal & Installation
1) ECU is located behind right rear quarter panel trim. See
Fig. 16 . Disconnect negative battery cable. Remove quarter panel
mounti ng screws and trim clip.
2) Carefully remove quarter panel trim. Disconnect ECU wiring
harness connector. Remove ECU mounting bolts/nuts and ECU. To install,
reverse removal procedure.