wiring MITSUBISHI MONTERO 1991 Owners Manual

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* S U SPEN SIO N U NIF O RM IN SPEC TIO N G UID ELIN ES *

1 991 M it s u bis h i M onte ro
GENERAL INFORMATION
Steering, Suspension, Wheel Alignment, Wheels and Tires
Motorist Assurance Program
Standards For Automotive Repair
All Makes and Models
INTRODUCTION TO MOTORIST ASSURANCE PROGRAM (MAP)
CONTENTS
Motorist Assurance Program (MAP)
OVERVIEW
OVERVIEW OF SERVICE REQUIREMENTS & SUGGESTIONS
Steering and Suspension
AIR RIDE SUSPENSION
AIR RIDE SUSPENSION - AIR SHOCKS AND AIR STRUTS
AIR RIDE SUSPENSION - AIR SPRING VALVES
AIR RIDE SUSPENSION - AIR SPRINGS
AIR RIDE SUSPENSION - COMPRESSORS
AIR RIDE SUSPENSION - HEIGHT SENSORS
AIR RIDE SUSPENSION - MODULES
AIR RIDE SUSPENSION - RELAYS (COMPRESSOR)
AIR RIDE SUSPENSION - SWITCHES (ON/OFF)
AIR RIDE SUSPENSION - TORSION SPRINGS (COUNTER BALANCING)
AIR RIDE SUSPENSION - TUBING
AIR RIDE SUSPENSION - WARNING LAMPS
AIR RIDE SUSPENSION - WIRING HARNESSES
BALL JOINTS
BUSHINGS
CENTER LINKS
CONTROL ARM SHAFTS
CONTROL ARMS
DRAG LINKS
ELECTRONIC RIDE CONTROL SHOCKS AND STRUTS
IDLER ARMS
KING PINS
PITMAN ARMS
POWER STEERING HOSES
POWER STEERING (HYDRAULIC) PUMPS
RADIUS ARMS
RELAY RODS
SHOCK ABSORBERS, STRUT CARTRIDGES AND STRUT ASSEMBLIES
SPINDLES
SPRINGS - COIL, LEAF AND TORSION BAR
STEEL POWER STEERING LINES
STEERING ARMS
STEERING DAMPERS
STEERING GEARS (EXCEPT RACK AND PINION)
STEERING GEARS - RACK AND PINION
STEERING KNUCKLES
STRIKE OUT BUMPERS
STRUT RODS
STRUT UPPER BEARING PLATE ASSEMBLIES
SWAY BAR LINKS
SWAY BARS

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AIR RIDE SUSPENSION - WARNING LAMPS
AIR RIDE SUSPENSION - WARNING LAMP INSPECTION








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Condition Code Procedure
Bulb burned out ......... A ............ Require replacement.
Warning light does
not come on during
bulb check ............. .. . Further inspection required to
determine cause.
Warning light flashes ... .. . Further inspection required to
determine cause.
Warning light is
intermittent ........... .. . Further inspection required to
determine cause.
Warning light stays
on after initial
bulb check ............. .. . Further inspection required to
determine cause.









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AIR RIDE SUSPENSION - WIRING HARNESSES
AIR RIDE SUSPENSION - WIRING HARNESS INSPECTION








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Condition Code Procedure
Connector bent .......... A .. Require repair or replacement.
Connector broken ........ A .. Require repair or replacement.
Connector loose ......... A .. Require repair or replacement.
Damaged (cut, burned, or
chafed) ................ A .. Require repair or replacement.
Excessive resistance .... B .. Require repair or replacement.
Fuse blown .............. A ............ Require replacement.
Fusible link blown ...... A ............ Require replacement.
Open .................... A .. Require repair or replacement.
Poor ground ............. A .. Require repair or replacement.
Routed incorrectly ...... B .. Require rerouting according to
vehicle manufacturer's
specifications.
Shorted ................. A .. Require repair or replacement.
Terminal bent ........... A .. Require repair or replacement.
Terminal broken ......... A .. Require repair or replacement.
Terminal corroded ....... A .. Require repair or replacement.
Terminal loose .......... A .. Require repair or replacement.









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BALL JOINTS
Before requiring or suggesting ball joint replacement, the
approved OEM procedure must be used to measure ball joint wear. The
measurement(s) obtained, along with the vehicle manufacturer's
specifications, must be noted on the inspection report. Some states
require that these measurements also appear on the invoice.
NOTE: The term "perceptible movement," defined as any visible
movement in any direction, has been the industry standard
for determining the need for replacement of follower ball
joints. Some vehicle manufacturers are now publishing
specifications for follower ball joints that were

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I - S YSTE M /C O M PO NEN T T E STS

1991 M it s u bis h i M onte ro
1991 ENGINE PERFORMANCE
System & Component Testing
Chrysler Motors: Ram-50
Mitsubishi: Montero, Pickup
INTRODUCTION
Before testing separate components or systems, perform
procedures in F - BASIC TESTING article in the ENGINE PERFORMANCE
Section. Since many computer controlled and monitored components set a
trouble code if they malfunction, also perform procedures in G - TESTS
W/CODES article in the ENGINE PERFORMANCE Section.
NOTE: Testing individual components does not isolate shorts or
opens. Perform all voltage tests with a Digital
Volt-Ohmmeter (DVOM) with a minimum 10-megohm input
impedance, unless stated otherwise in test procedure. Use
ohmmeter to isolate wiring harness shorts or opens.
COMPUTERIZED ENGINE CONTROLS
CONTROL UNIT
NOTE: To identify ECU power and ground circuits, see appropriate
L - WIRING DIAGRAMS article in the ENGINE PERFORMANCE
Section.
Ground Circuits
1) ECU is located near right kick panel. Turn ignition off.
Using an ohmmeter, check for continuity between ground and ECU
terminals No. 101 and 106. Resistance should be zero ohms. If
resistance is not zero ohms, repair open circuit between ECU connector
and ground.
2) Connect voltmeter negative lead to ground. Connect
positive lead to ECU ground terminals as in step 1). With vehicle
running, voltmeter should indicate less than one volt. If voltmeter
reading is greater than one volt, check for open, corrosion or loose
connection in ground circuit.
Power Circuits
ECU is located near right kick panel. Turn ignition on. Check
for battery voltage on ECU terminals No. 102 and 107. If battery
voltage is not present, check operation of MPI control relay. See
RELAYS under MOTORS, RELAYS & SOLENOIDS.
ENGINE SENSORS & SWITCHES
BAROMETRIC PRESSURE SENSOR
Sensor is a component part of airflow sensor assembly. See G
- TESTS W/CODES article in the ENGINE PERFORMANCE Section.
COOLANT TEMPERATURE SENSOR
1) Remove coolant temperature sensor located near thermostat
housing (2-wire connector). Place end of sensor in water with terminal\

mechanism. Testing information is not available from manufacturer. See
appropriate wiring diagram in L - WIRING DIAGRAMS article in the
ENGINE PERFORMANCE Section.
INTAKE AIR TEMPERATURE SENSOR
1) Sensor is incorporated in airflow sensor assembly inside
air filter housing. Disconnect airflow sensor connector. See Fig. 1.
Fig. 1: Airflow Sensor Connector Terminal ID
Courtesy of Mitsubishi Motor Sales of America.
2) Measure resistance between terminals No. 4 and 6 of
airflow sensor connector (sensor side of connector). For
specifications, see INTAKE AIR TEMPERATURE SENSOR RESISTANCE table.
Replace airflow sensor assembly if air temperature sensor resistance
is not within specification.

INTAKE AIR TEMP SENSOR RESISTANCE TABLE








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TemperatureF (C) Ohms
All Models
32 (0) ........................ 6000
68 (20) ....................... 2700
176 (80) ....................... 400









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MOTOR POSITION SENSOR
NOTE: Some engines are not equipped with Motor Position Sensor
(MPS). MPS may be a separate unit mounted to throttle body
or it may be incorporated in ISC motor assembly, depending
upon vehicle application.
Pickup 2.4L & Ram-50 2.4L
1) Disconnect MPS connector. See Fig. 2. Connect ohmmeter
lead to ground. Connect other ohmmeter lead to terminal No. 3 of
sensor connector. If continuity is not present, repair wiring harness
as necessary. If continuity is present, go to next step.
Fig. 2: Motor Pos. Sensor Connector Term. ID
Courtesy of Mitsubishi Motor Sales of America.
2) Connect ohmmeter leads to terminals No. 2 and 3.
Resistance should be 4000-6000 ohms. If resistance is not within

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

not present, check circuit between relay and battery, including
fusible link No. 1.
Fig. 10: MPI Control Relay Connector Term. ID (8 Pin)
Courtesy of Mitsubishi Motor Sales of America.
2) Disconnect wiring harness connector at relay. Remove
relay. Check continuity between terminals No. 1 and 4, terminals No. 2
and 4 and terminals No. 3 and 4. If there is no continuity, go to next

step. If there is continuity, replace relay.
3) Check diode operation between terminals No. 6 and 8. If
there is continuity in only one direction, go to next step. If there
is no continuity in either direction or if there is continuity in both
directions, replace relay.
4) Measure resistance between terminals No. 6 and 7. If
resistance is approximately 35 ohms, go to next step. If resistance is
not approximately 35 ohms, replace relay.
5) Measure resistance between terminals No. 2 and 5 and
between terminals No. 3 and 5. In both tests, if resistance is
approximately 95 ohms, go to next step. If resistance is not
approximately 95 ohms, replace relay.
6) Connect positive lead of 12-volt source to terminal No. 7
and negative lead to terminal No. 6. If there is continuity between
terminals No. 1 and 4, go to next step. If there is no continuity,
replace relay.
7) Connect positive lead of 12-volt source to terminal No. 5
and negative lead to terminal No. 2. If there is continuity between
terminals No. 1 and 4, go to next step. If there is no continuity,
replace relay.
8) Connect positive lead of 12-volt source to terminal No. 5
and negative lead to terminal No. 3. If there is continuity between
terminals No. 1 and 4, go to next step. If there is no continuity,
replace relay.
9) Connect positive lead of 12-volt source to terminal No. 8
and negative lead to terminal No. 6. If there is continuity between
terminals No. 3 and 4 and between terminals No. 2 and 4, relay is
okay. If there is no continuity, replace relay.
SOLENOIDS
Fuel Pressure Control Solenoid Valve
See FUEL DELIVERY under FUEL SYSTEM.
Fuel Injector Solenoids
See FUEL CONTROL under FUEL SYSTEM.
FUEL SYSTEM
FUEL DELIVERY
NOTE: For fuel system pressure testing, see F - BASIC TESTING
article in the ENGINE PERFORMANCE Section.
FUEL CONTROL
Fuel Injectors
1) Using a stethoscope, check operating sound of injector(s)\
during engine cranking or idling. If clicking sound is heard,
injectors are okay. If clicking sound is not heard at each injector,
go to step 2).
2) Disconnect injector electrical connector. Measure
resistance between injector connector terminals. At 68
F (20C), if
resistance is not 13-16 ohms, replace injector.
3) If resistance is within specification, check injector
wiring circuit for open or short to ground. If wiring circuit tests
okay, replace injector.
IDLE CONTROL SYSTEM
NOTE: ISC motor adjusts throttle plate angle to regulate idle air

right several times. Start engine, and turn steering wheel back and
forth to raise fluid temperature to approximately 122-140F (50-60C).
3) With engine idling, gradually close shutoff valve of
pressure gauge to increase hydraulic pressure. If idle speed does not
increase 200-250 RPM when fluid pressure reaches 213-284 psi (15-20
kg/cm
), replace power steering idle-up switch.
4) Gradually open shutoff valve. If engine speed does not
return to curb idle speed between 100-142 psi (7-10 kg/cm
), replace
power steering idle-up switch. Remove testing equipment. Bleed air
from system as in step 2).
IGNITION SYSTEM
NOTE: For basic ignition checks, see F - BASIC TESTING article in
ENGINE PERFORMANCE Section.
TIMING CONTROL SYSTEMS
Crank Angle Sensor
Crank angle sensor is located inside distributor on SOHC
engines and is attached to cylinder head on DOHC engines. If
malfunction occurs, Code 22 will set. For testing procedure, see
appropriate G - TESTS W/CODES article in the ENGINE PERFORMANCE
Section.
EMISSION SYSTEMS & SUB-SYSTEMS
EXHAUST GAS RECIRCULATION (EGR)
System Testing (Federal)
1) Disconnect Green-striped hose from throttle body, and
connect vacuum pump to hose end. Plug nipple where hose was connected
to throttle body. When engine is cold, 122
F (50C) or less, and at
idle, apply vacuum to disconnected hose. If idle does not change and
vacuum bleeds down, system is okay.
2) When engine is hot, 205
F (95C), and at idle, apply 1.8
in. Hg. If idle does not change and vacuum holds, system is okay.
Using a vacuum pump, apply 7.7 in. Hg. If idle becomes unstable or
engine stalls (and vacuum holds), system is okay.
System Testing (California)
1) Connect vacuum "T" fitting into Green-striped hose from
EGR valve, and connect vacuum gauge to vacuum tee. When engine coolant
temperature is 68
F (20C) or less and engine is idling, snap throttle
open to race engine. If no change in vacuum reading is detected on
gauge, system is okay.
2) When engine coolant temperature is 158
F (70C) or more
and engine is idling, snap throttle open to race engine. If vacuum
increases to 3.9 in. Hg or higher, system is okay.
3) Using vacuum pump, apply specified vacuum to open EGR
valve. See EGR VALVE SPECIFICATIONS table. If idle becomes unstable or
engine stalls, system is okay.
EGR Control Solenoid Valve (Pickup & Ram-50, California)
1) EGR control solenoid valve is located near left shock
tower. Label and disconnect vacuum hoses and wiring harness from
solenoid valve.
2) Connect hand vacuum pump to vacuum nipple where Green-
striped vacuum hose was connected. Apply vacuum and ensure vacuum does
not hold. Apply battery voltage to one terminal of solenoid, and
ground other. Ensure vacuum holds.

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