light MITSUBISHI MONTERO 1991 Service Manual

Remove horn pad and steering wheel. See Figs. 1-6. See
STEERING COLUMN TESTING/REMOVAL & INSTALLATION table for figure
directory on specific model. Remove knee protector and upper and lower
column covers (if necessary). On Eclipse, remove hood lock release
handle and air ducts. On all models, remove any necessary cable bands,
and remove steering column switch. To install, reverse removal
procedure.
Removal (Stealth & 3000GT)
1) Disconnect negative battery cable. Wait 30 seconds, and
then remove air bag module mounting nut from back side of module. To
remove clockspring connector from air bag module, force lock outward
and pry it using a flat screwdriver. Ensure no undue force is exerted
on connector when it is removed. Remove air bag module, and store it
face up. See Fig. 7.
CAUTION: Wait at least 30 seconds after disconnecting battery cable
before continuing servicing.
2) Remove steering wheel and knee protector. Remove upper and
lower column covers. Remove air ducts. Remove right and left steering
column switches.
WARNING: DO NOT hammer on steering wheel. Collapsible steering column
mechanism may be damaged.
Installation
1) To install, reverse removal procedure. Before installing
steering wheel, center clockspring by lining up NEUTRAL mark of
clockspring with mark on steering column. To complete installation,
reverse removal procedure. DO NOT reconnect negative battery cable
until air bag module is installed.
2) After installation is complete, turn ignition on from
passenger side of vehicle. Supplemental Restraint System (SRS) light
on dash should come on for approximately 7 seconds. If SRS light does
not come on, stays on or flashes, repair air bag system.

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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

connector portion of sensor slightly above water.
2) Gradually heat water and read resistance values across
terminal connectors. See COOLANT TEMPERATURE SENSOR RESISTANCE table.
If resistance is not within specification, replace sensor.
COOLANT TEMPERATURE SENSOR RESISTANCE TABLE









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TemperatureF (C) Ohms
Montero & Pickup 3.0L
32 (0) ............................. 5900
68 (20) ............................ 2500
104 (40) ........................... 2700
176 (80) ............................ 300
All Others
32 (0) ............................. 5900
68 (20) ............................ 2500
104 (40) ........................... 1100
176 (80) ............................ 300









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CRANK ANGLE SENSOR
See IGNITION SYSTEM.
DETONATION SENSOR
See IGNITION SYSTEM.
EGR TEMPERATURE SENSOR
California
See EXHAUST GAS RECIRCULATION (EGR) under EMISSION SYSTEMS &
SUB-SYSTEMS.
IDLE POSITION SWITCH
NOTE: Idle position switch is incorporated in idle speed control
motor assembly, motor position sensor or throttle position
sensor, depending upon vehicle application.
Pickup 2.4L & Ram-50 2.4L
1) Disconnect motor position sensor (MPS) connector. Connect\
ohmmeter lead between ground and MPS connector terminal No. 4. See
Fig. 2 .
2) With accelerator pedal pressed, no continuity should be
present. With accelerator pedal released, continuity should be
present. If switch continuity is not as specified, replace MPS.
Montero, Pickup 3.0L & Ram-50 3.0L
1) Disconnect throttle position sensor (TPS) connector.
Connect ohmmeter between TPS connector terminals No. 1 and 2. See
Fig. 6 .
2) With accelerator pedal pressed, no continuity should be
present. With accelerator pedal released, continuity should be
present. If idle switch continuity is not as specified, replace TPS.
INHIBITOR SWITCH
Automatic Transmission
Switch is mounted to automatic transaxle, near shift lever

Fig. 12: ISC Motor Connector Term. ID (6 Pin)
Courtesy of Mitsubishi Motor Sales of America.
2) Apply source ground lead to ISC motor connector terminals
No. 3 and 6. Note slight movement of ISC motor plunger. Remove ground
leads from terminals No. 3 and 6.
3) Apply and remove source ground at terminals No. 1 and 6, 1
and 4, 3 and 4, and 3 and 6. Note slight movement of ISC motor plunger
during each phase of test.
4) Beginning at terminal No. 6, reverse grounding sequence
following same procedure specified in step 2). If motor does not
operate when grounding any of specified terminals, replace ISC motor.
IDLE SPEED CONTROL (ISC) MOTOR RESISTANCE TEST
Pickup 2.4L & Ram-50 2.4L
Disconnect ISC motor connector. Connect ohmmeter between
terminals No. 1 and 2 of ISC motor connector. See Fig. 11. If
resistance is not 5-35 ohms at 68
F (20C), replace ISC motor
assembly.
Montero, Pickup 3.0L & Ram-50 3.0L
Measure resistance between terminals No. 1 and 2, 2 and 3, 4
and 5, and 5 and 6 of ISC motor connector. See Fig. 12. In each case,
if resistance is not 28-33 ohms at 68
F (20C), replace ISC motor

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G - T E STS W /C O DES
1991 Mitsubishi Montero
1990-91 ENGINE PERFORMANCE
Chrysler Motors/Mitsubishi Self-Diagnostics
Dodge; Colt, Colt Vista, Colt Wagon
Eagle; Summit
Mitsubishi; Eclipse, Galant, Mirage, Montero, Precis (1990)
Plymouth; Colt, Colt Vista, Colt Wagon
INTRODUCTION
If no faults were found while performing F - BASIC TESTING,
proceed with self-diagnostics. If no fault codes or only pass codes
are present after entering self-diagnostics, proceed to H - TESTS W/O
CODES article for diagnosis by symptom (i.e. ROUGH IDLE, NO START,
etc.).
SELF-DIAGNOSTIC SYSTEM
Use Chrysler Motors code charts when using Chrysler's
Diagnostic Readout Box (DRB-II). If DRB-II is not available or if
working on a Mitsubishi Motors vehicle, system diagnosis can only be
accomplished using a voltmeter or appropriate scan tester. To diagnose
Chrysler Motors and Mitsubishi models using a voltmeter, see
ENTERING ON-BOARD DIAGNOSTICS (USING VOLTMETER) in this article.
SYSTEM DIAGNOSIS
SYSTEM DIAGNOSIS DESCRIPTION
NOTE: Chrysler Motors recommends using DRB-II to diagnose system.
Voltmeter usage has limited diagnostic capabilities but can
be used if DRB-II is not available or if working on a
Mitsubishi Motors vehicle.
The Engine Control Unit (ECU) monitors several different
engine control system circuits. If an abnormal input signal occurs, a
fault code is stored in ECU memory and given a fault code number. Each
circuit has its own fault number and message. A specific fault code
indicates a particular system failure, but it DOES NOT indicate that
cause of failure is necessarily within system. A fault code DOES NOT
condemn any specific component; it simply points out a probable
malfunctioning area. If a critical fault code is set, the ECU will
turn on CHECK ENGINE light. All fault codes except speed sensor are
considered critical.
Fault codes can be confirmed by using a voltmeter on Chrysler
Motors and Mitsubishi models or Chrysler's Diagnostic Readout Box
(DRB-II) on Chrysler Motors vehicles. See
ENTERING ON-BOARD DIAGNOSTICS (USING VOLTMETER) or ENTERING ON-BOARD
DIAGNOSTICS (USING DRB-II) in this article. By using the DRB-II, the
self-diagnostic capabilities of this system can simplify testing and
reduce diagnostic time.
System malfunctions encountered are identified as either hard
failures or intermittent failures as determined by the ECU.
HARD FAILURES
Hard failures cause CHECK ENGINE light to illuminate and
remain on until the malfunction is repaired. If light comes on and

remains on (light may flash) during vehicle operation, cause of
malfunction must be determined by using DIAGNOSTIC FAULT CHARTS (if
testing with voltmeter) or diagnostic CODE CHARTS (if testing with
DRB-II). If a sensor fails, ECU will use a substitute value in its
calculations to continue engine operation. In this condition, vehicle
is functional, but loss of good driveability may result.
INTERMITTENT FAILURES
Intermittent failures may cause CHECK ENGINE light to flicker
or illuminate and go out after the intermittent fault goes away.
However, the corresponding trouble code will be retained in ECU
memory. If related fault does not reoccur within a certain time frame,
related trouble code will be erased from ECU memory. Intermittent
failures may be caused by a sensor, connector or wiring related
problems. See INTERMITTENTS in H - TESTS W/O CODES article.
PRETEST INSPECTION
Before proceeding with diagnosis, the following precautions
must be followed:
* Vehicle must have a fully charged battery and functional
charging system.
* Visually inspect connectors and circuit wiring being worked
on.
* DO NOT disconnect battery or ECU. This will erase any fault
codes stored in ECU.
* DO NOT cause short circuits when performing electrical tests.
This will set additional fault codes, making diagnosis of original
problem more difficult.
* DO NOT use a test light in place of a voltmeter.
* When checking for spark, ensure coil wire is NO more than
1/4" from ground. If coil wire is more than 1/4" from ground,
damage to vehicle electronics and/or ECU may result.
* DO NOT prolong testing of fuel injectors. Engine may
hydrostatically (liquid) lock.
* When a vehicle has multiple fault codes, always repair lowest
number fault code first.
* If DRB-II is being used to diagnose system, always perform
verification test after repairs are made.
ENTERING ON-BOARD DIAGNOSTICS (USING VOLTMETER)
1) Before entering on-board diagnostics, refer to PRETEST
INSPECTION in this article. Turn ignition switch to OFF position.
Locate self-diagnostic connector. See SELF-DIAGNOSTIC TEST CONNECTOR
LOCATION table. Using an analog voltmeter, connect voltmeter positive
lead to self-diagnostic connector terminal No. 1 and negative lead to
terminal No. 12 (ground). See Fig. 6.
2) Turn ignition switch to ON position and disclosure of ECU
memory will begin. If 2 or more systems are non-functional, they are
indicated by order of increasing code number. Indication is made by
12-volt pulses of voltmeter pointer. A constant repetition of short
12-volt pulses indicates system is normal. If system is abnormal,
voltmeter will pulse between zero and 12 volts.
3) Signals will appear on voltmeter as long and short 12-volt
pulses. Long pulses represent tens; short pulses represent ones. For
example 4 long pulses and 3 short pulses indicates Code 43. See

44 (5) ..... Open or short in either ignition coil circuit
( 1) - Except Montero & Sigma.
( 2) - Will not turn on CHECK ENGINE light.
( 3) - 2.0L turbo only.
( 4) - California only. Except Sigma.
( 5) - Chrysler Motors models only.









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CLEARING CODES
Using DRB-II, from main menu select ADJUSTMENTS. Enter ERASE
FAULTS. Follow DRB-II instructions to accomplish this task. If DRB-II
is not available, fault codes may be cleared by disconnecting negative
battery cable for at least 10 seconds, allowing ECU to clear fault
codes.
TEST CHARTS
* PLEASE READ THIS FIRST *
NOTE: The following charts are supplied for Chrysler Motors
vehicles.
NS-1: TESTING IGNITION CIRCUIT - 1.5L
Fig. 7: Circuit Diagram NS-1 (1.5L) (1 of 2)
Fig. 8: Circuit Diagram NS-1 (1.5L) (2 of 2)

voltage or resistance values using a DVOM while attempting to
reproduce conditions which may cause intermittent fault. A status
change on DVOM indicates a fault has been located.
When using a DVOM to pinpoint faults, monitor voltage reading
with ignition on, or vehicle running. Ensure ignition is in OFF
position or negative battery cable is disconnected when monitoring
circuit resistance. Change in ohmmeter reading during test procedures
indicates area of fault.
TEST PROCEDURES
Intermittent Simulation
To reproduce conditions which cause intermittent fault, use
the following methods:
* Lightly vibrate component.
* Heat component.
* Wiggle or bend wiring harness.
* Spray component with water.
* Remove/apply vacuum source.
Monitor circuit/component voltage or resistance while
simulating intermittent fault conditions. If vehicle is running,
monitor for self-diagnostic codes. Use test results to identify a
faulty component or circuit.

Inhibitor Switch (Automatic Transmission Only)
Inhibitor switch senses position of transmission select
lever, indicating engine load due to automatic transmission
engagement. Based on this signal, ECU commands ISC motor to increase
throttle angle, maintaining optimum idle speed.
Intake Air Temperature Sensor
Incorporated in airflow sensor assembly, this resistor-based
sensor measures temperature of incoming air and supplies air density
information to ECU.
Motor Position Sensor (MPS)
Incorporated in ISC motor (or separate unit on some models),
senses ISC motor plunger position and sends electrical signal to ECU.
Oxygen (O2) Sensor
Located in exhaust system, generates an output voltage.
Output voltage varies with oxygen content of exhaust gas stream. ECU
adjusts air/fuel mixture based on signals from oxygen sensor.
Power Steering Oil Pressure Switch
Detects increase in power steering oil pressure. When power
steering oil pressure increases, switch contacts close, signalling
ECU. ECU commands ISC motor, raising idle speed to compensate for drop
in engine RPM due to power steering load.
TDC Sensor
See CRANKSHAFT ANGLE & TDC SENSOR ASSEMBLY.
Throttle Position Sensor (TPS)
A variable resistor mounted on throttle body. ECU uses
voltage signal received from TPS to determine throttle plate angle.
Vehicle Speed Sensor
Located in speedometer in instrument cluster, uses a reed
switch to sense speedometer gear revolutions. ECU uses gear
revolutions to determine vehicle speed.
OUTPUT SIGNALS
NOTE: Vehicles are equipped with different combinations of
computer-controlled components. Not all components listed
below are used on every vehicle. For theory and operation on
each output component, refer to the system indicated in
brackets after component.
CHECK ENGINE Light
See SELF DIAGNOSTIC SYSTEM.
EGR Control Solenoid Valve
See EXHAUST GAS RECIRCULATION (EGR) CONTROL under EMISSION
SYSTEMS.
Fuel Injectors
See FUEL CONTROL under FUEL SYSTEM.
Fuel Pressure Control Solenoid Valve (Turbo Only)
See FUEL DELIVERY under FUEL SYSTEM.
Fuel Pressure Regulator
See FUEL DELIVERY under FUEL SYSTEM.
Fuel Pump Relay (MPI Control Relay)

EMISSION SYSTEMS
EXHAUST GAS RECIRCULATION (EGR) CONTROL
Federal (Non-Turbocharged)
To lower oxides of nitrogen (NOx) exhaust emissions, a non-
computer controlled exhaust gas recirculation system is used. EGR
operation is controlled by throttle body ported vacuum. Vacuum is
routed through thermovalve to prevent EGR operation at low engine
temperatures.
Spring pressure holds EGR valve closed during low vacuum
conditions (engine idling or wide open throttle). When vacuum pressure\
increases and overcomes EGR spring pressure, EGR valve is lifted and
allows exhaust gases to flow into intake manifold for combustion.
California & Turbocharged
ECU controls EGR operation by activating EGR control solenoid
valve according to engine load. When engine is cold, ECU signals EGR
control solenoid valve to deactivate EGR.
California models are equipped with an EGR temperature
sensor. When EGR malfunction occurs, EGR temperature decreases and ECU
illuminates CHECK ENGINE (malfunction indicator) light.
EGR Control Solenoid Valve
Denies or allows vacuum supply to EGR valve, based upon ECU
commands.
Thermovalve
Denies or allows vacuum supply to EGR valve based on coolant
temperature.
EVAPORATIVE CONTROL
Fuel evaporation system prevents fuel vapor from entering
atmosphere. System consists of a special fuel tank with vapor
separator tanks (if equipped), vacuum relief filler cap, overfill
limiter (2-way valve), fuel check valve, thermovalve (if equipped),
charcoal canister, purge control valve, purge control solenoid valve
and connecting lines and hoses.
Purge Control Solenoid Valve
When engine is off, fuel vapors are vented into charcoal
canister. When engine is warmed to normal operating temperature and
running above idle, ECU energizes purge control solenoid valve,
allowing vacuum to purge valve.
Canister vapors are then drawn through purge valve into
intake manifold for burning. Purge control solenoid valve remains
closed during idle and engine warm-up to reduce HC and CO emissions.
HIGH ALTITUDE CONTROL (HAC)
This system compensates for variations in altitude. When
atmospheric (barometric) pressure sensor determines vehicle is above
preset altitude, ECU compensates by adjusting air/fuel mixture and
ignition timing. If HAC system is inoperative, there will be an
increase in emissions.
PCV VALVE
Positive Crankcase Ventilation (PCV) valve operates in the
closed crankcase ventilation system. Closed crankcase ventilation