
DIFFERENTIAL LOCK - REAR
1998 Mitsubishi Montero
1997-98 DRIVE AXLES
Mitsubishi Rear Differential Lock
Montero, Montero Sport
DESCRIPTION & OPERATION
The rear differential lock system is designed to be used only
when low-speed wheel spin occurs in a ditch, or on a slippery or
uneven surface. The indicator light will blink when switch is turned
on as system completes locking operation. After the differential is
locked, the light will stop blinking and remain on.
The rear differential lock system will not lock with vehicle
in 4H or 2H position, and if vehicle speed is greater than 7 MPH.
Vehicle speed should be maintained at less than 12 MPH during rear
differential lock operation.
NOTE: The Anti-lock Brake System (ABS) does not operate when the
rear differential is locked. It is normal for the ABS
warning light to be on at this time.
COMPONENT LOCATIONS
Rear Differential Lock Air Pump
Air pump is located under left side of rear seat.
Rear Differential Lock Control Unit
Control unit is located under left side lower quarter trim
panel in rear compartment.
Rear Differential Lock Switch
Lock switch is located on lower center of instrument panel,
below radio.
Rear Differential Lock Detection Switch
Lock detection switch is located on rear differential
carrier.
TROUBLE SHOOTING
INDICATOR LIGHT FLASHES WHEN LOCK SWITCH IS TURNED ON
If vehicle speed is greater than 7 MPH, reduce speed to less
than 3 MPH. If vehicle speed is less than 7 MPH, rotate steering wheel
to right and left to reset light.
INDICATOR LIGHT FLASHES WHEN LOCK SWITCH IS TURNED OFF
If indicator flashes after lock switch is turned off, depress
and release accelerator several times while driving straight ahead to
reset light.
TESTING
REAR DIFFERENTIAL LOCK AIR PUMP

Using voltmeter, backprobe rear differential lock control
unit connector between terminal No. 6 (ground) and specified terminal
under specified conditions. See WIRING DIAGRAMS. See
REAR DIFFERENTIAL LOCK CONTROL UNIT VOLTAGE table. If voltage is not
as specified, replace control unit.
REAR DIFFERENTIAL LOCK CONTROL UNIT VOLTAGE
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Terminal No. Circuit Voltage
3 .................... Ignition Switch (IG1) ............ ( 1) Zero
3 .................... Ignition Switch (IG1) ......... ( 2) Battery
9 (ON side) ............. Rear Lock Switch .......... ( 2)( 3) Zero
1 (OFF side) ............ Rear Lock Switch ....... ( 2)( 4) Battery
10 ...................... Indicator Light ........... ( 2)( 5) Zero
10 ...................... Indicator Light ........ ( 2)( 6) Battery
2 .................. Vehicle Speed Reed Switch ............. ( 7) 5
8 ................. Rear Lock Detection Switch ...... ( 2)( 5) Zero
8 ................. Rear Lock Detection Switch ... ( 2)( 6) Battery
4 ..................... Rear Lock Air Pump ....... ( 2)( 8) Battery
4 ..................... Rear Lock Air Pump .......... ( 2)( 9) Zero
5 ................... Center Lock Operation ..... ( 2)( 10) Battery
5 ...................... Detection Switch ....... ( 2)( 10) Battery
5 ...................... Detection Switch .......... ( 2)( 11) Zero
( 1) - Ignition off.
( 2) - Ignition on.
( 3) - ON side or OFF side.
( 4) - In Neutral.
( 5) - Rear differential locked.
( 6) - Rear differential free.
( 7) - Select Drive or 1st gear and drive forward slowly.
( 8) - When filing or holding.
( 9) - When releasing.
( 10 ) - Center differential free.
( 11 ) - Center differential locked.
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REAR DIFFERENTIAL LOCK DETECTION SWITCH
NOTE: DO NOT apply more pressure than required to bring pressure
gauge reading to about 4 psi (.28 kg/cm ).
1) Raise and support vehicle. Remove air pipe and air hose
connections. Connect a pressure gauge and air regulator (for adjusting
compressed air pressure) to air hose. See Fig. 2. Using air regulator,
adjust compressed air pressure until pressure gauge indicates about 4
psi (.28 kg/cm
).
2) While an assistant holds one wheel on one side of vehicle
stationary, slowly turn wheel on other side of vehicle. Using
ohmmeter, check for continuity between rear differential lock
detection switch connector terminals.
3) With air supplied, continuity should exist. With air
released, continuity should not exist. If continuity is not as
specified, replace lock detection switch.

FLANGES
FLEX PLATES
FLUID LEVEL INDICATORS
FLUIDS AND LUBRICANTS
FLYWHEELS
FORCE MOTORS
GUIDES
HALF SHAFTS
HOSES, LINES AND TUBES
HOUSINGS (BELL, CASE, TAIL (EXTENSION) AND AUXILIARY)
INTERMEDIATE SHAFT SUPPORT BEARINGS
KEY INTERLOCK SYSTEMS
LIMITED SLIPS
LINES
LINKAGES (EXTERNAL)
LOCKING HUB ASSEMBLIES
LOCKING HUB CONTROL KNOBS
LUBRICANTS
METAL-CLAD SEALS
METALASTIC JOINTS
MODULATOR PINS
MODULATORS
MOUNTS (ENGINE, TRANSAXLE AND TRANSMISSION)
ODOMETER DRIVES (MECHANICAL)
ODOMETER HEADS (MECHANICAL)
OIL PANS
PANS
PILOT HOLES
PRESSURE PLATES
PRESSURE SWITCHES
RACES
RUBBER JOINTS (METALASTIC)
SCREENS
SEALS
SEALS (METAL-CLAD)
SELECTOR INTERLOCK SYSTEMS
SERVOS
SHIFT INTERLOCK SYSTEMS (SELECTOR AND KEY INTERLOCK SYSTEMS)
SENSORS
SIDE COVERS
SLIP YOKES
SOLENOIDS
SPEED SENSORS (ELECTRONIC WHEEL AND VEHICLE)
SPEEDOMETER-DRIVEN GEAR HOUSINGS
SPEEDOMETER/ODOMETER DRIVES (MECHANICAL)
SPEEDOMETER/ODOMETER HEADS (MECHANICAL)
SPEEDOMETERS AND ODOMETERS (ELECTRONIC)
SWITCHES
TONE WHEELS
TOOTHED RINGS (TONE WHEELS)
TORQUE CONVERTERS
TRANSAXLE MOUNTS
TRANSDUCERS (TRANSMISSION)
TRANSMISSION COOLERS
TRANSMISSION MOUNTS
TRANSMISSION PANS
TRANSMISSION RANGE INDICATORS (PRNDL)
TUBES
UNIVERSAL JOINTS (CARDON OR CROSS TYPE)
VACUUM CONTROLS
VACUUM HOSES
VACUUM MOTORS
VACUUM-OPERATED SWITCHES

IGNITION SWITCHES
INDICATOR LIGHTS
KEYLESS ENTRY KEYPADS AND TRANSMITTERS
KEYLESS ENTRY TRANSMITTERS
LEDS
LENSES
MICROPHONES
MIRRORS (ELECTROCHROMATIC AND HEATED)
MOTORS
NEUTRAL SAFETY SWITCHES
ODOMETERS
ODOMETERS, SPEEDOMETERS AND TACHOMETERS (CABLE-DRIVEN)
PULLEYS
RECEIVERS, AMPLIFIERS, EQUALIZERS AND SUB-WOOFER VOLUME CONTROLS
RELAY BOXES
RELAYS
SEALED BEAMS
SEAT HEATERS
SECURITY ALARM SENSORS
SIRENS
SOLENOIDS
SPEAKERS AND MICROPHONES
SPEEDOMETER AND TACHOMETER LINKAGES AND CABLES
SPEEDOMETER CABLES
SPEEDOMETERS
STARTERS
SUB-WOOFER VOLUME CONTROLS
SWITCHES
TACHOMETER CABLES
TACHOMETERS
TAPE PLAYERS AND CD PLAYERS
TENSIONERS
TIMERS
TIRE PRESSURE SENSORS
TRANSCEIVERS
TRANSDUCERS
VACUUM ACCUMULATORS (RESERVOIRS)
VACUUM RESERVOIRS
VOLTAGE REGULATORS
WASHER FLUID LEVEL SENDERS
WASHER PUMPS
WIPER ARMS AND BLADES
WIPER BLADES
WIPER HOSES AND NOZZLES
WIPER LINKAGES
WIPER NOZZLES
WIPER PUMP RESERVOIRS
WIRING HARNESSES AND CONNECTORS
INTRODUCTION TO MOTORIST ASSURANCE PROGRAM (MAP)
OVERVIEW OF MOTORIST ASSURANCE PROGRAM
The Motorist Assurance Program is the consumer outreach
effort of the Automotive Maintenance and Repair Association, Inc.
(AMRA). Participation in the Motorist Assurance Program is drawn from
retailers, suppliers, independent repair facilities, vehicle
manufacturers and industry associations.
Our organization's mission is to strengthen the relationship
between the consumer and the auto repair industry. We produce
materials that give motorists the information and encouragement to
take greater responsibility for their vehicles-through proper,

Attaching hardware
broken ................. A ... Require repair or replacement
of hardware.
Attaching hardware
missing ................ C .......... Require replacement of
hardware.
Attaching hardware not
functioning ............ A ... Require repair or replacement
of hardware.
Connector broken ........ A .. Require repair or replacement.
Connector melted ........ A ........... (1) Require repair or
replacement.
Connector missing ....... C ............ Require replacement.
Inoperative ............. A ........... ( 2) Require repair or
replacement.
Missing ................. C ............ Require replacement.
Out of adjustment ....... B ............. Require adjustment.
Sound quality poor ...... A .. Require repair or replacement.
Further inspection required.
Terminal broken ......... A .. Require repair or replacement.
Terminal burned, affecting
performance ............ A ........... ( 1) Require repair or
replacement.
Terminal burned, not
affecting performance .. 2 .. Suggest repair or replacement.
Terminal corroded,
affecting performance .. A .. Require repair or replacement.
Terminal corroded, not
affecting performance .. 2 .. Suggest repair or replacement.
Terminal loose, affecting
performance ............ B .. Require repair or replacement.
Terminal loose, not
affecting performance .. 1 .. Suggest repair or replacement.
Wire lead burned ........ A .. Require repair or replacement.
Wire lead conductors
exposed ................ B .. Require repair or replacement.
Wire lead open .......... A .. Require repair or replacement.
Wire lead shorted ....... A .. Require repair or replacement.
( 1) - Determine cause and correct prior to repair or
replacement of part.
( 2) - Inoperative includes intermittent operation.
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IGNITION SWITCHES
See SWITCHES.
INDICATOR LIGHTS
INDICATOR LIGHT INSPECTION \
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Condition Code Procedure
Does not come on during
bulb check ............. .. ......... ( 1) Further inspection
required.
Fails to function properly
during test mode ....... .. ......... ( 1) Further inspection
required.
On constantly ........... .. ......... ( 1) Further inspection
required.

If equipped, the EMR light (some models may use a reminder
flag) reminds vehicle operator that an emission system maintenance is
required. This indicator is activated after a predetermined
time/mileage.
When performing a smog check inspection, ensure EMR indicator
is not activated. On models using an EMR light, light should glow when
ignition switch is turned to ON position and should turn off when
engine is running.
If an EMR flag is present or an EMR light stays on with
engine running, fail vehicle and service or replace applicable
emission-related components. To reset an EMR indicator, refer to
appropriate MAINTENANCE REMINDER LIGHTS in the MAINTENANCE section.
MALFUNCTION INDICATOR LIGHT (MIL)
The Malfunction Indicator Light (MIL) is used to alert
vehicle operator that the computerized engine control system has
detected a malfunction (when it stays on all the time with engine
running). On some models, the MIL may also be used to display trouble
codes.
As a bulb and system check, malfunction indicator light will
glow when ignition switch is turned to ON position and engine is not
running. When engine is started, light should go out.

system.
3) Using scan tool, read Fuel Tank Differential Pressure
(FTDP) sensor (item 73). Using hand-held pressure/vacuum pump, apply\
0.42 psi. If scan tool reading reaches 0.42 psi, go to next step. If
reading does not reach 0.42 psi, go to step 8).
4) Disconnect EVAP canister purge hose. Connect Purge Flow
Indicator (MB995061) between EVAP canister and disconnected hose. Turn\
engine on and allow it to reach operating temperature. Turn all lights
and accessories off. Place transmission in Park or Neutral. Observe
purge flow indicator while increasing engine RPM several times. If
purge flow indicator reads less than 2.5 SCFH (20 cm(3)/sec), check
EVAP canister purge hose and EVAP canister port for clogging. If hose
and port are okay, check EVAP purge solenoid. See DTC P0443. If
solenoid is okay, replace EVAP canister. Go to step 20).
5) Using scan tool, read Engine Coolant Temperature (ECT)
sensor temperature (item 21). Compare scan tool reading with
temperature gauge reading. If readings are about the same, go to next
step. If readings are not about the same, go to DTC P0115 test.
6) Using a thermometer, check engine compartment ambient
temperature. Using scan tool, read Intake Air Temperature (IAT) sensor\
temperature (item 13). Compare IAT sensor and thermometer readings. If\
readings are not about the same, go to DTC P0110 test. If readings are
about the same, go to next step.
7) Using scan tool, read Power Steering Pressure (PSP) switc\
h
status (item 27). Switch status should read ON when steering wheel is
turned. If switch status is as specified, go to step 20). If switch
status is not as specified, go to DTC P0551 test.
8) Remove fuel cap. Install a fuel tank filler tube adapter
in place of fuel cap. Plug fuel filler tube adapter hose. Disconnect
and plug air filter-to-EVAP vent solenoid hose at air filter.
Disconnect intake manifold plenum-to-EVAP purge solenoid at intake
manifold plenum. Install a "T" fitting between vacuum hose and intake
manifold plenum. Connect hand-held pressure/vacuum pump to "T"
fitting. Go to next step.
CAUTION: DO NOT apply more than 0.57 psi in following step. Applying
more than specified psi can crack fuel tank.
NOTE: Ensure fuel tank is at least 1/4 full. The lower the fuel
level in fuel tank, the longer it takes to pressurize fuel
system.
9) Using scan tool, read Fuel Tank Differential Pressure
(FTDP) sensor (item 73). Using hand-held pressure/vacuum pump, apply\
0.42 psi. If scan tool reading reaches 0.42 psi, replace fuel cap. Go
to step 20). If reading does not reach 0.42 psi, go to next step.
10) Disconnect hand-held pressure/vacuum pump from "T"
fitting. Install an evaporative emission system tester in place of
vacuum held pump and apply 0.49 psi. Wait two minutes. If pressure
drops less than 0.20 psi, go to next step. If pressure drops 0.29 psi
or more, go to step 13).
11) Disconnect EVAP purge solenoid-to-EVAP canister hose at
EVAP canister. Connect hand-held pressure/vacuum pump to hose and
apply 0.9 psi. If pressure is not maintained, check EVAP purge
solenoid for leak. If EVAP purge solenoid is okay, replace hose. Go to
step 24). If pressure is maintained, go to next step.
12) Disconnect EVAP vent solenoid-to-EVAP canister hose at
EVAP canister. Connect hand-held pressure/vacuum pump to hose and
apply 0.9 psi. If pressure is not maintained, check EVAP vent solenoid
for leak. If EVAP vent solenoid is okay, replace hose. Go to step 20).
If pressure is maintained, replace EVAP canister. Go to step 24).
13) Ensure hoses are properly routed and connected. See M -

Starters
Generator .................................. Generators & Regulators
Engine Performance
Power Distribution
Generic Electronic Module (GEM) ............... Body Control Modules\
Electronic Suspension
Glow Plug Relay ................................. Engine Performance
Glow Plugs ...................................... Engine Performance
Grounds ........................................ Ground Distribution
Headlight Door Module .............................. Headlight Doors
Headlight Relay .................................. Headlight Systems
Daytime Running Lights
Headlights ....................................... Headlight Systems
Daytime Running Lights
Heated Oxygen Sensor(s) (HO2S) .................. Engine Performan\
ce
Heated Windshield Control Module ................ Heated Windshields
Height Sensor ................................ Electronic Suspension
Horns ..................................... Steering Column Switches
Horn Relay ................................ Steering Column Switches
Idle Air Control (IAC) Motor/Valve .............. Engine Performance\
Ignition Coil(s) ................................ Engine Performance\
Ignition Key Lock Cylinder ....................... Anti-Theft System
Ignition Module ................................. Engine Performance
Ignition Switch ................................. Power Distribution
Engine Performance
Generators & Regulators
Starters
Illuminated Entry Module .............. Illumination/Interior Lights
Illumination Lights ................... Illumination/Interior Lights
Impact Sensor ............................. Air Bag Restraint System
Inertia Fuel Shutoff Switch ..................... Engine Performance
Inhibit Relay ............................................. Starters
Instrument Cluster ........................ Analog Instrument Panels
Intake Air Temperature (IAT) Sensor ............. Engine Performance\
Interior Lights ....................... Illumination/Interior Lights
Interlock Switch .......................................... Starters
Junction Block .................................. Power Distribution
Keyless Entry Receiver ........................ Remote Keyless Entry
Key Reminder Switch ....................................... Starters
Knock Sensor .................................... Engine Performance
Lamp Control Module ................................ Exterior Lights
License Plate Lamp ................................. Exterior Lights
Lighting Control Module ................... Lighting Control Modules
Anti-Theft System
Daytime Running Lights
Headlight Systems
Lower Relay .................................. Power Convertible Top
Malfunction Indicator Light (MIL) ............... Engine Performance\
Instrument Panels
Manifold Absolute Pressure (MAP) Sensor ......... Engine Performance\
Mass Airflow (MAF) Sensor ....................... Engine Performance\
Mega Fuse .................................. Generators & Regulators
Memory Seat/Mirror Module ........................... Memory Systems
Mirror Defogger ............................... Rear Window Defogger
Moon Roof Motor .................................... Power Moon Roof
Moon Roof Relay .................................... Power Moon Roof
Multi-Function Control Module ...................... Warning Systems
Neutral Safety Switch ..................................... Starters
Oil Level Switch ................................ Engine Performance
Oil Pressure Switch/Sending Unit .......... Analog Instrument Panels
Engine Performance
Overhead Console .................................. Overhead Console
Oxygen Sensor(s) (O2S) .......................... Engine Performan\
ce