1991 MITSUBISHI MONTERO check engine light

screws. Remove dash panel.
4) Remove blower duct, center duct and defroster ducts. See
Fig. 2. Disconnect heater wiring harness from heater unit. Remove
heater center support brackets. Remove heater unit. Remove heater core
cover plate and joint hose. Remove heater core from heater unit.
Installation
1) To install, reverse removal procedure. Insert heater hoses
fully into pipes, and clamp securely to prevent leaks.
2) When filling radiator with coolant, first open heater
control valve fully and run engine to circulate coolant and discharge
air from inside heater and engine cooling system. Stop engine, and add
coolant.
3) Adjust all control cables. When installing heater hose
grommets, apply sealer. After installing heater control assembly,
ensure each lever operates smoothly.
HEATER CONTROL PANEL
Removal (Montero)
1) Remove heater control knob and heater fan switch knob.
Remove center console. Remove defroster nozzle at temperature control
cable side.
2) Remove lap heater duct and glove box stopper, and push
glove box forward and down. Disconnect inside/outside control cable
from blower assembly.
3) Disconnect control cables from heater unit. Remove heater
control panel mounting screws, and pull out panel slightly. Disconnect
heater fan switch harness connectors. Remove heater control panel.
Remove heater fan switch from heater control panel.
Installation
1) Place air outlet change-over lever at closed position.
With heater side air outlet change-over damper lever in position,
connect inner cable to lever, and secure cable casing using clips.
2) Place heater control lever at OFF position. With heater
control lever in position, connect inner cable to lever, and secure
cable casing using clips.
3) Place inside/outside air change-over lever at INSIDE
position. With heater side inside/outside air change-over damper lever
in position, connect inner cable to lever, and secure cable casing
using clips.
4) Set control lever to each position to check for correct
operation. If lever does not operate correctly, adjust by moving outer
wire at clipped point. Ensure each control lever moves smoothly. If
any noise or stiff movement exists, apply multipurpose grease to all
moving parts.
NOTE: When mounting heater control panel to instrument panel,
tighten upper bolts to instrument panel so they also secure
center panel.
Removal & Installation (Pickup & Ram-50)
Remove cluster panel. Remove all control cables at heater.
Remove heater control panel. To install, reverse removal procedure.
Adjust cables as necessary.
WIRING DIAGRAMS

OIL PRESSURE GAUGE
Circuit Test
Disconnect oil pressure gauge wiring connector from sending
unit inside the engine compartment. Connect a 12-volt test light
between harness connector terminal and ground. Turn ignition on, but
DO NOT start engine. If test light comes on and gauge needle moves, go
to GAUGE RESISTANCE TEST. If test light does not come on and gauge
needle does not move, repair wiring to sending unit.
Gauge Resistance Test
Remove instrument cluster from instrument panel. See
INSTRUMENT CLUSTER under REMOVAL & INSTALLATION. Check continuity
between oil pressure gauge terminals. See Fig. 4 or Fig. 5. See
OIL PRESSURE GAUGE RESISTANCE SPECIFICATIONS table. If resistance is
not within specification, replace oil pressure gauge.
OIL PRESSURE GAUGE RESISTANCE SPECIFICATIONS TABLE









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Application Ohms
Montero ...................................... 50
Pickup & Ram-50 ........................... 37-47









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Fig. 4: Oil Pressure Gauge Test Terminal ID (Pickup & Ram-50)
Courtesy of Chrysler Motors

Calibration Test
Adjust tire pressure to standard value. Using a calibrated,
reliable speedometer tester, compare reading of vehicle speedometer to
speedometer tester. See SPEEDOMETER ALLOWABLE VARIATION table. Replace
speedometer if necessary.
SPEEDOMETER ALLOWABLE VARIATION TABLE









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MPH (km/h) Allowable Variation MPH (km/h)
20 (32) .......................... 19-22 (31-35)
40 (64) .......................... 38-44 (61-71)
60 (97) ......................... 57-66 (92-106)
80 (129) ....................... 76-88 (122-142)
100 (161) ..................... 94-110 (151-177)









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TACHOMETER
NOTE: DO NOT reverse polarity when installing tachometer, as diode
and transistor may be damaged.
Calibration Test
Connect a calibrated, reliable tach-dwell meter to vehicle
ignition system. Operate engine at various speeds (RPM). See
TACHOMETER ALLOWABLE VARIATION table. If comparison between tach-dwell
meter and vehicle tachometer readings do not fall in the standard
range of permissible variation, replace vehicle tachometer.
TACHOMETER ALLOWABLE VARIATION TABLE









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Engine Speed (RPM) Allowable Variation (RPM)
1000 .................................. 900-1100
3000 ................................. 2850-3150
5000 ................................. 4750-5250
6000 ................................. 5700-6300









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TEMPERATURE GAUGE
CAUTION: DO NOT connect sender wire directly to ground during test.
Circuit Test
Disconnect temperature sender wire from sending unit. Connect
a 12-volt, 3.4-watt test bulb between connector terminal and ground.
Turn ignition switch to ON position. If test bulb flashes and
temperature gauge needle moves, go to SENSOR RESISTANCE TEST. If test
light does not flash and gauge needle does not move, repair wiring to
sending unit.
Sensor Resistance Test
Remove thermosensor (sending unit) from engine block. Place
sending unit in hot water of 158
F (70C) temperature. Check sensor
resistance with an ohmmeter. Thermosensor resistance should be 90-117
ohms at 158
F (70C). If thermosensor resistance in okay, go to GAUGE
RESISTANCE TEST. Replace thermosensor if resistance is not as
specified.
Gauge Resistance Test
Remove instrument cluster from instrument panel. See
INSTRUMENT CLUSTER under REMOVAL & INSTALLATION. Measure resistance
between temperature gauge terminals at rear of cluster or combination

1985-87 ........ (2) 2.4L 4-Cyl. .......... ( 4) 60,000
1988 ............... 3.0L V6 .............. ( 3) 60,000
1989-93 .... ( 2) 2.0L 4-Cyl. (DOHC) ....... ( 4) 60,000
2.0L 4-Cyl. (SOHC) ........ ( 4) 60,000
1994-96 .... ( 2) 2.4L 4-Cyl. (DOHC) ....... ( 4) 60,000
2.4L 4-Cyl. (SOHC) ........ ( 4) 60,000
Mirage
1985-96 ........ ( 2) 1.5L 4-Cyl. .............. 60,000
1985-88 ..... ( 2) 1.6L 4-Cyl. Turbo ........... 60,000
1989, 1991 ..... ( 2) 1.6L 4-Cyl. .............. 60,000
1993-96 ........... 1.8L 4-Cyl ................ 60,000
Precis
1987-93 ........ ( 2) 1.5L 4-Cyl. .............. 60,000
Sigma
1989-90 ............ 3.0L V6 .............. ( 3) 60,000
Tredia
1983-88 .......... 1.8L 4-Cyl. ............ ( 4) 60,000
2.0L 4-Cyl. ............ ( 4) 60,000
3000GT
1991-96 .......... ( 2) 3.0L V6 ................ 60,000
Light Trucks
Montero
1985-96 ............ 3.0L V6 .............. ( 3) 60,000
1994-96 ............ 3.5L V6 .............. ( 3) 60,000
Pickup
1983-89 ........... 2.0L 4-Cyl. ........... ( 3) 60,000
1983-86 ... ( 2) 2.3L 4-Cyl. Turbo Diesel .. ( 4) 60,000
1990-96 ........... 2.4L 4-Cyl. ........... ( 4) 60,000
3.0L V6 .............. ( 3) 60,000
Van
1987-90 ........... 2.4L 4-Cyl. ........... ( 4) 60,000
( 1) - Other interference engine applications may exist which
are not indicated here.
( 2) - Interference engine. Check for possible damage to
piston(s) or valve(s) if there has been a timing belt
failure.
( 3) - Although the vehicle manufacturer does not recommend a
specific scheduled maintenance interval, aftermarket
belt manufacturers suggest the belt be replaced at
60,000 mile intervals.
( 4) - Vehicle manufacturer recommends replacing all belts at
the same time.









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2.6L Engine ........................................... 45
2.6L Optional ......................................... 45
3.0L V6 ........................................... (1) 24
3.5L V6 ........................................... ( 1) 24
( 1) - Check hood clearance on 1986 and newer models.









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CAUTIONS & WARNINGS
SUPPLEMENTAL RESTRAINT SYSTEM (SRS) AIR BAG SYSTEM
NOTE: See the AIR BAG RESTRAINT SYSTEM article in the
ACCESSORIES/SAFETY EQUIPMENT Section.
The SRS has no user-servicable parts. Always have servicing
done by an authorized dealer.
When performing maintenance on air bag equipped vehicles
always observe proper safety precautions.
WARNING: To avoid injury from accidental air bag deployment, read and
carefully follow all warnings and service precautions. See
appropriate AIR BAG RESTRAINT SYSTEM article in the
ACCESSORIES/SAFETY EQUIPMENT section.
CAUTION: Disconnect negative battery cable before servicing any air
bag system, steering column or passenger side dash
component. After any repair, turn ignition key to the ON
position from passenger's side of vehicle in case of
accidental air bag inflation
ANTI-LOCK BRAKE SYSTEM (ABS)
CAUTION: Never mix different diameter tires. On loose or uneven
surfaces, the ABS system may require longer stopping
distances than conventional brake systems. Exercise caution
when removing mud or snow from the wheels so as not to
damage the ABS wiring or speed sensors.
BATTERY WARNING
WARNING: When battery is disconnected, vehicles equipped with
computers may lose memory data. When battery power is
restored, driveability problems may exist on some vehicles.
These vehicles may require a relearn procedure. See
appropriate COMPUTER RELEARN PROCEDURES article in the
GENERAL INFORMATION section below.
REPLACING BLOWN FUSES
Before replacing a blown fuse, remove ignition key, turn off
all lights and accessories to avoid damaging the electrical system. Be
sure to use fuse with the correct indicated amperage rating. The use
of an incorrect amperage rating fuse may result in a dangerous
electrical system overload.
BRAKE PAD WEAR INDICATOR
Indicator will cause a squealing or scraping noise, warning
that brake pads need replacement.

Light comes on with the ignition switch in the "ON" position
as a bulb check, but should go out shortly after engine is started. If
light remains on or comes on while driving, it indicates low oil
pressure and possible system malfunction. Have the system checked and
serviced immediately. Do not operate vehicle until cause is located
and corrected.
ALTERNATOR WARNING LIGHT
Light comes on with the ignition switch in the "ON" position
as a bulb check and goes out after engine is started. If light remains
on or comes on while driving, it indicates possible fault in the
electrical charging system. The alternator belt may be loose or
broken. Have the system checked and serviced promptly. Do not drive
vehicle if alternator belt is loose or broken.
"BRAKE" WARNING LIGHT
Light comes on with the ignition switch in the "ON" position
as a bulb check and goes out after engine is started. Light will also
come on with the parking brake fully or partially engaged. If light
remains on or comes on at any other time, it indicates low brake fluid
level in the master cylinder reservoir or the parking brake switch may
be damaged. Have the system checked and serviced immediately if brake
fluid level is low. Do not continue driving if further trouble is
experienced.
"CHECK ENGINE" WARNING LIGHT (IF EQUIPPED)
Light is designed to come on briefly with the ignition switch
in the "ON" position as a bulb check. If light remains on or comes on
while driving, it indicates fault in an exhaust gas related component
and the system is not functioning properly. Have the system checked
and serviced as soon as possible.
"MAINTENANCE REQUIRED" WARNING LIGHT (IF EQUIPPED)
Light comes on at 50,000 miles, 80,000 miles, 100,000 miles
and 120,000 miles (150,000 miles on 1990-91 models) as a service
reminder that it is time for the periodic maintenance of the emission
control system. Have the system inspected and serviced as necessary
when light comes on. Continued operation of vehicle without having
system serviced after warning light comes on may adversely affect
proper performance of the emission control system. Reset warning
light, after the system has been checked, by pushing the reset switch
in front of the combination meter. Remove the warning light bulb after
the last maintenance service at 120,000 miles (150,000 miles on 1990-
91 models).
"A/T TEMPERATURE" WARNING LIGHT (IF EQUIPPED)
Light comes on when the automatic transmission fluid
temperature becomes abnormally high. If light comes on, reduce engine
speed, stop car and put it in "P" (Park) position. Leave engine
running until light goes out. Normal vehicle operation may be resumed
after light has gone out. If light does not go out, have the system
checked and serviced as necessary.
WHEEL LOCK INDICATOR LIGHT (IF EQUIPPED)
Light comes on when automatic free-wheeling hubs are locked.
If ignition is turned off, indicator light will not come on when

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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