1991 MITSUBISHI MONTERO wiring diagram

MOTORS
ISC Motor
See IDLE CONTROL SYSTEM.
RELAYS
NOTE: For internal wiring diagram of MPI control relay, see
appropriate L - WIRING DIAGRAMS article in the ENGINE
PERFORMANCE Section.
MPI Control Relay (Montero, Pickup 3.0L & Ram-50 3.0L)
1) MPI control relay is located near right kick panel. Check
for battery voltage at terminal No. 10 of relay connector. See Fig. 9.
If battery voltage is present, go to step 3). If battery voltage is
not present, check circuit between relay and battery, including
fusible link No. 1.
Fig. 9: MPI Control Relay Connector Term. ID (10 Pin)
Courtesy of Mitsubishi Motor Sales of America.
2) Apply battery voltage to terminal No. 10. Battery voltage
should not be present at terminals No. 4 and 5. Apply battery voltage
to terminal No. 10, and ground terminal No. 8. Battery voltage should
now be present at terminals No. 4 and 5.
3) Apply battery voltage to terminal No. 3. Battery voltage
should not be present at terminal No. 2. Apply battery voltage to
terminal No. 3, and ground terminal No. 7. Battery voltage should now
be present at terminal No. 2.
4) Apply battery voltage to terminal No. 9. Battery voltage
should not be present at terminal No. 2. Apply battery voltage to
terminal No. 9, and ground terminal No. 6. Battery voltage should now
be present at terminal No. 2. Replace relay if it does not test as
specified.
MPI Control Relay (Pickup 2.4L & Ram-50)
1) MPI control relay is located near right kick panel. Check
for battery voltage at terminal No. 4 of relay connector. See Fig. 10.
If battery voltage is present, go to step 3). If battery voltage is

SYSTE M W IR IN G D IA G RAM S

1991 M it s u bis h i M onte ro
1991 System Wiring Diagrams
Mitsubishi - Montero
COOLING FAN
Cooling Fan Circuit
DEFOGGERS

that all of the engine control systems are operating as they were
designed to. Therefore, they are not the cause of the driveability
problem.
The following additional items can not be overlooked as possible
causes of a driveability problem.
1. THROTTLE VALVE AREA - Dirt or ice buildup causing rough idle and
stalling.
2. ENGINE IGNITION TIMING - Must be set with timing terminal
grounded.
3. ENGINE VACUUM - Must be normal for your altitude.
4. ENGINE VALVE TIMING - To specifications.
5. ENGINE COMPRESSION - To specifications.
6. ENGINE P.C.V. SYSTEM - Must flow freely.
7. ENGINE EXHAUST SYSTEM - Must be free of any restrictions.
8. POWER BRAKE BOOSTER - No internal vacuum leaks.
9. TORQUE CONVERTER CONDITION - May cause very low power at breakaway
or high speed (Only 1 condition at a time).
10. FUEL CONTAMINATION - High alcohol or water content.
11. FUEL INJECTORS - Rough idle may be caused by injector wiring not
connected to correct injector.
12. ENGINE SECONDARY IGNITION CHECK - Abnormal scope patterns.
13. TECHNICAL SERVICE BULLETINS - Any that apply to vehicle.
14. All air intake piping and vacuum hoses must be in place and
secure. The proper air filter element must be used.
15. FUEL PRESSURE - Must be correct.
Specification: With no vacuum at the regulator:
48 PSI on V6 & non-turbo 4 Cyl. engines
36 PSI on turbo engines
NS-1: TESTING IGNITION CIRCUIT - 1.6L
Fig. 75: Circuit Diagram NS-1 (1.6L)

2. ENGINE IGNITION TIMING - Must be set with timing terminal
grounded.
3. ENGINE VACUUM - Must be normal for your altitude.
4. ENGINE VALVE TIMING - To specifications.
5. ENGINE COMPRESSION - To specifications.
6. ENGINE P.C.V. SYSTEM - Must flow freely.
7. ENGINE EXHAUST SYSTEM - Must be free of any restrictions.
8. POWER BRAKE BOOSTER - No internal vacuum leaks.
9. TORQUE CONVERTER CONDITION - May cause very low power at breakaway
or high speed (Only 1 condition at a time).
10. FUEL CONTAMINATION - High alcohol or water content.
11. FUEL INJECTORS - Rough idle may be caused by injector wiring not
connected to correct injector.
12. ENGINE SECONDARY IGNITION CHECK - Abnormal scope patterns.
13. TECHNICAL SERVICE BULLETINS - Any that apply to vehicle.
14. All air intake piping and vacuum hoses must be in place and
secure. The proper air filter element must be used.
15. FUEL PRESSURE - Must be correct.
Specification: With no vacuum at the regulator:
48 PSI on V6 & non-turbo 4 Cyl. engines
36 PSI on turbo engines
NS-1: IGNITION CHECK FLOW CHARTS - 2.0L
Fig. 235: NS-1 Flow Chart & Circuit Diagram (2.0L) (1 of 5)

input device usage on specific models, see appropriate wiring diagram
in M - WIRING DIAGRAMS.
Air Conditioner Switch
When A/C is turned on, signal is sent to ECU. With engine at
idle, ECU increases idle speed through Idle Speed Control (ISC) motor.\
Airflow Sensor
Incorporated in airflow sensor assembly, airflow sensor is a
Karmen Vortex-type sensor which measures intake airflow rate.
Intake air flows through tunnel in airflow sensor assembly.
Airflow sensor transmits radio frequency signals across direction of
incoming airflow, downstream of vortex. Intake air encounters vortex,
causing turbulence in tunnel.
Turbulence disrupts radio frequency, causing variations in
transmission. Airflow sensor converts frequency transmitted into a
proportionate electrical signal which is sent to ECU.
Airflow Sensor Assembly
Mounted inside air cleaner, incorporates airflow sensor,
atmospheric pressure sensor and intake air temperature sensor.
Atmospheric (Barometric) Pressure Sensor
Incorporated in the airflow sensor assembly, converts
atmospheric pressure to electrical signal which is sent to ECU. ECU
adjusts air/fuel ratio and ignition timing according to altitude.
Coolant Temperature Sensor
Converts coolant temperature to electrical signal for use by
ECU. ECU uses coolant temperature information for controlling fuel
enrichment when engine is cold.
Crankshaft Angle & TDC Sensor Assembly
Assembly is located in distributor on SOHC engines. On DOHC
engines, which use Direct (or Distributorless) Ignition System (DIS)\
,
assembly is separate unit mounted in place of distributor. Assembly
consists of triggering disc (mounted on shaft) and stationary optical
sensing unit. Camshaft drives shaft, triggering optical sensing unit.
ECU determines crank angle and TDC based on signals received from
optical sensing unit.
Detonation Sensor (Turbo Only)
Located in cylinder block, senses engine vibration during
detonation (knock). Sensor converts vibration into electrical signal.
ECU retards ignition timing based on this signal.
Engine Speed (Tach Signal)
ECU uses ignition coil tach signal to determine engine speed.
Idle Position Switch
On all DOHC engines and Sigma 3.0L, idle position switch is
separate switch mounted on throttle body. On all other models, idle
position switch is incorporated in ISC motor or throttle position
sensor, depending on vehicle application. When throttle valve is
closed, switch is activated. When throttle valve is at any other
position, switch is deactivated. This input from idle position switch
is used by ECU for controlling fuel delivery time during deceleration.
Ignition Timing Adjustment Terminal
Used for adjusting base ignition timing. When terminal is
grounded, ECU timing control function is by-passed, allowing base
timing to be adjusted.

TORQUE SPECIFICATIONS TABLE








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Application Ft. Lbs. (N.m)
Adapter-To-Transfer Bearing Retainer ......... (1) 14 (19)
Case Nuts & Bolts .......................... 22-31 (30-42)
Center Differential Case Bolts ................... 48 (65)
Chain Cover Bolt ........................... 22-31 (30-42)
Detection Switch ............................. ( 1) 27 (36)
Drain Plug ................................. 22-26 (30-35)
Dynamic Damper ................................... 52 (70)
High-Low Shift Rail Plug ..................... ( 1) 24 (33)
Interlock Plunger Plug ................. ( 1) 22-26 (30-35)
Lock Plate Bolts ........................... 11-16 (15-22)
Oil Dam Cover ................................ ( 1) 14 (19)
Oil Filler Plug ............................ 22-26 (30-35)
Output Shaft Cover Bolt .................... 11-16 (15-22)
Poppet Plug .................................. ( 1) 27 (36)
Pulse Rotor Bolt ....................... ( 2) 11-16 (15-22)
Rear Cover Bolt ............................ 11-16 (15-22)
Rear Output Shaft Lock Nut ............... 74-96 (100-130)
Seal Plug .............................. ( 2) 22-31 (30-42)
Speedometer Sleeve Clamp Bolt .............. 11-16 (15-22)
4WD Indicator Light Switch ................... ( 2) 22 (33)
INCH Lbs. (N.m)
Pulse Generator Bolt .................. ( 2) 89-106 (10-12)
Side Cover Bolt ............................. 71-89 (8-10)
( 1) - Montero.
( 2) - Ram-50.









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WIRING DIAGRAMS

ALTERNATOR article








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Alternator Blown fuse See WIRING DIAGRAMS
Light Stays Off
With Ignition
Switch ON
Defective alternator See Testing in
ALTERNATOR article
Defective indicator light See Indicator Warning
bulb or socket Lights in STANDARD
INSTRUMENTS in the
ACCESSORIES &
EQUIPMENT section









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Alternator Short in alternator wiring See On-Vehicle Tests
Light Stays OFF in ALTERNATOR article
With Ignition
Switch ON
Defective rectifier bridge See Bench Tests in
ALTERNATOR article









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Lights or Fuses Defective alternator wiring See On-Vehicle Tests
Burn Out in ALTERNATOR article
Frequently
Defective regulator See Regulator Check in
ALTERNATOR article
Defective battery Check and replace as
necessary









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Ammeter Gauge Loose or worn drive belt Check alternator drive
Shows Discharge belt tension and
condition. See Belt
Adjustment in TUNE-UP
article in the
TUNE-UP section
Defective wiring Check all wires and
wire connections
Defective alternator or See Bench Tests and
regulator On-Vehicle Tests in
ALTERNATOR article
Defective ammeter, or See Testing in
improper ammeter wiring STANDARD INSTRUMENTS
connection in the ACCESSORIES &
EQUIPMENT section









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Noisy Loose drive pulley Tighten drive pulley
Alternator attaching nut
Loose mounting bolts Tighten all alternator
mounting bolts
Worn or dirty bearings See Bearing
Replacement
ALTERNATOR article

article in the ACCESSORIES/SAFETY EQUIP Section.
REAR WIPER MOTOR
Removal & Installation
Remove wiper blade and arm assembly. Remove tailgate trim, 2
bolts and wiper motor. To install, reverse removal procedure. Ensure
grommet is in good condition.
REAR WIPER RELAY
Removal & Installation
Rear wiper relay (Except Montero), is located behind right
rear quarter trim. On Montero, relay is located to right of heater
blower housing.
REAR WIPER SWITCH
Removal & Installation
Using flat-bladed tool, pry rear wiper switch from instrument
panel and remove wiring connector. To install, connect wiring
connector, and push switch into instrument panel.
WIRING DIAGRAMS
See appropriate chassis wiring diagram in the WIRING DIAGRAMS
section.