1991 MITSUBISHI MONTERO heater

Fig. 7: Brakes, Steering, & Suspension
Fig. 8: Air Conditioning, Heater & Ventilation

95C). Disconnect oxygen sensor connector. See Fig. 5. Connect
ohmmeter between heater terminals of oxygen sensor connector as
specified in OXYGEN SENSOR 4-WIRE CONNECTOR TERMINAL IDENTIFICATION
table. This test checks resistance of oxygen sensor heater element.
Fig. 5: O2 Sensor Connector Term. ID
Courtesy of Mitsubishi Motor Sales of America.
2) When oxygen sensor is at 68
F (20C), resistance should be
approximately 12 ohms (20 ohms on 3.0L models). If resistance is not
within specification, replace oxygen sensor.
CAUTION: DO NOT apply battery voltage to oxygen sensor output
terminals. Damage to oxygen sensor could result.
3) Apply battery voltage to oxygen sensor heater terminals as
specified in OXYGEN SENSOR 4-WIRE CONNECTOR TERMINAL IDENTIFICATION
table. This heats oxygen sensor heater element.
4) Connect digital voltmeter between output terminals
specified in OXYGEN SENSOR 4-WIRE CONNECTOR TERMINAL IDENTIFICATION
table. Repeatedly race engine and observe oxygen sensor output
voltage. If oxygen sensor output voltage is not within 0.6-1.0 volt,
replace oxygen sensor.
OXYGEN SENSOR 4-WIRE CONNECTOR TERMINAL ID TABLE









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Heater Output

Fires With Key Flywheel runout contributes
released. Engine to the intermittent nature
Fires and Cranks
Normally









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AIR CONDITIONING & HEAT
AIR CONDITIONING TROUBLE SHOOTING
WARNING: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle
configuration. The purpose of this Trouble Shooting
information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting,
refer to SUBJECT, DIAGNOSTIC, or TESTING articles available
in the section(s) you are accessing.
BASIC AIR CONDITIONING TROUBLE SHOOTING CHART









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CONDITION POSSIBLE CAUSE








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Compressor Not Working
Compressor clutch circuit open.

Compressor clutch coil inoperative.

Poor clutch ground connection.

Fan belts loose.

Thermostatic switch inoperative.

Thermostatic switch not adjusted.

Ambient temperature switch open.

Superheat fuse blown.








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Excessive Noise or Vibration
Missing or loose mounting bolts.

Bad idler pulley bearings.

Fan belts not tightened correctly.

Compressor clutch contacting body.

Excessive system pressure.

Compressor oil level low.

Damaged clutch bearings.

Damaged reed valves.

Damaged compressor.








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Insufficient or No Cooling;
Compressor Working
Expansion valve inoperative.

Heater control valve stuck open.

Low system pressure.

Blocked condenser fins.

Blocked evaporator fins.

Vacuum system leak.

Vacuum motors inoperative.

Control cables improperly adjusted.

Restricted air inlet.

Mode doors binding.

Blower motor inoperative.

Temperature above system capacity.








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HEATER SYSTEM TROUBLE SHOOTING
NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle
configuration. The purpose of this Trouble Shooting
information is to provide a list of common causes to

problem symptoms. For model-specific Trouble Shooting,
refer to DIAGNOSTIC, or TESTING articles available in the
section(s) you are accessing.
BASIC HEATER SYSTEM TROUBLE SHOOTING CHART









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CONDITION POSSIBLE CAUSE








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Insufficient, Erratic,
or No Heat
Low Coolant Level

Incorrect thermostat.

Restricted coolant flow through
heater core.


Heater hoses plugged.

Misadjusted control cable.

Sticking heater control valve.

Vacuum hose leaking.

Vacuum hose blocked.

Vacuum motors inoperative.

Blocked air inlet.

Inoperative heater blower motor.

Oil residue on heater core fins.

Dirt on heater core fins.








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Too Much Heat
Improperly adjusted cables.

Sticking heater control valve.

No vacuum to heater control valve.

Temperature door stuck open.








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Air Flow Changes During
Acceleration
Vacuum system leak.

Bad check valve or reservoir.








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Air From Defroster At All
Times
Vacuum system leak.

Improperly adjusted control cables.

Inoperative vacuum motor.








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Blower Does Not Operate
Correctly
Blown fuse.

Blower motor windings open.

Resistors burned out.

Motor ground connection loose.

Wiring harness connections loose.

Blower motor switch inoperative.

Blower relay inoperative.

Fan binding or foreign object
in housing.


Fan blades broken or bent.








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BRAKES
BRAKE SYSTEM TROUBLE SHOOTING
NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle
configuration. The purpose of this Trouble Shooting
information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting,
refer to SUBJECT, DIAGNOSTIC, or TESTING articles available
in the section(s) you are accessing.

Water Pump Malfunction Replace Water Pump
Fan Clutch Malfunction Replace Fan Clutch
Retarded Ignition Timing Reset Ignition Timing
Cooling Fan Malfunction Test Cooling Fan/
Circuit
Cooling Fan Motor
Malfunction Test Fan Motor
Cooling Fan Relay
Malfunction Test Fan Relay
Faulty Radiator Cap Replace Radiator Cap
Broken/Slipping Fan Belt Replace Fan Belt
Restricted Exhaust Repair Exhaust System









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Corrosion Impurities In Coolant Clean/Flush System








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Coolant Leakage Damaged hose Replace Hose
Leaky Water Pump Replace Water Pump
Damaged Radiator Seam Replace/Repair Radiator
Leaky Thermostat Cover Replace Thermostat
Cover
Cylinder Head Problem Check Head/Head Gasket
Leaky Freeze Plugs Replace Freeze Plugs









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Recovery System Inoperative
Loose and/or Defective
Radiator Cap Replace Radiator Cap
Overflow Tube Clogged
and/or Leaking Repair Tube
Recovery Bottle Vent
Restricted Clean Vent









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No Heater Core Flow
Collapsed Heater Hose Replace Heater Hose
Plugged Heater Core Clean/Replace Heater
Core
Faulty Heater Valve Replace Heater Valve









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GASOLINE ENGINE - MECHANICAL TROUBLE SHOOTING
NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle
configuration. The purpose of this Trouble Shooting
information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting,
refer to SUBJECT, DIAGNOSTIC, or TESTING articles available

Fig. 3: Identifying Rear Wiper Motor Terminals (Montero)
Courtesy of Mitsubishi Motor Sales of America.
Automatic Stop Check (Montero)
1) Start motor operation by connecting battery voltage to one
terminal and grounding another terminal. See
REAR WIPER MOTOR OPERATION CHECK table. See Fig. 3. Disconnect wires
during operation to stop motor in mid-sweep.
2) Jumper terminals No. 2 and 3 together. Connect battery
voltage to remaining terminal and ground wiper motor bracket. Ensure
motor parks wiper arm.
REAR WIPER RELAY
Operation Check (Montero)
Relay is located to right of heater blower assembly. Leave
intermittent relay connected to wiring harness. Operate rear wiper and
check voltage at terminal No. 1. See Fig. 4. There should be 12 volts
when rear wiper stops. Zero volts should be present when rear wiper is
operating.
Fig. 4: Identifying Rear Wiper Relay Terminals
Courtesy of Mitsubishi Motor Sales of America.
REAR WIPER SWITCH

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.

Fig. 8: Diode (Light Emitting)
Fig. 9: Defogger Grid
Fig. 10: Fuse
Fig. 11: Fusible Link
Fig. 12: Ground
Fig. 13: Glow Plug Resistor (In-Line) or Mirror Heater
Fig. 14: Injector (Diesel) or Photocell (Gasoline)