1991 MITSUBISHI MONTERO cooling

Terminal burned, affecting
performance ............ A ........... (1) Require repair or
replacement.
Terminal burned, not
affecting performance .. 2 .. Suggest repair or replacement.
Terminal corroded,
affecting performance .. A .. Require repair or replacement.
Terminal corroded, not
affecting performance .. 2 .. Suggest repair or replacement.
Terminal loose, affecting
performance ............ B .. Require repair or replacement.
Terminal loose, not
affecting performance .. 1 .. Suggest repair or replacement.
Vibration ............... 1 ............ Suggest replacement.
Wire lead conductors
exposed ................ B .. Require repair or replacement.
Wire lead corroded ...... A .. Require repair or replacement.
Wire lead open .......... A .. Require repair or replacement.
Wire lead shorted ....... A .. Require repair or replacement.
( 1) - Determine cause and correct prior to repair or
replacement of part.
( 2) - Check fan motor/controls. Inoperative includes
intermittent operation or out of OEM specification.









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WATER PUMPS (NON-ELECTRIC)
WATER PUMP (NON-ELECTRIC) INSPECTION








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Condition Code Procedure
Attaching hardware
broken ................. A ... Require repair or replacement
of hardware.
Attaching hardware
corroded ............... A ... Require repair or replacement
of hardware.
Attaching hardware
missing ................ C .......... Require replacement of
hardware.
Attaching hardware not
functioning ............ A ... Require repair or replacement
of hardware.
Corrosion (internal) is
excessive, affecting
performance ............ A ............ Require replacement.
Corrosion (internal) is
excessive, not affecting
performance ............ 2 . Suggest cooling system service.
Inoperative ............. A ........ ( 1) Require replacement.
Leaking ................. A ............ Require replacement.
Noisy ................... A ............ Require replacement.
Rotation incorrect for
application ............ B .. Require repair or replacement.
Shaft bent .............. A ............ Require replacement.
( 1) - Inoperative includes intermittent operation or out of
OEM specification.









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WIRING HARNESSES AND CONNECTORS

1 - 20 Amp (Yellow)
Hazard Light, Dome Light, Clock
2 - 10 Amp (Red)
Taillights
3 - 10 Amp (Red)
Turn Signal Lights
4 - 10 Amp (Red)
Back-Up Lights, Gauges
5 - 15 Amp (Light Blue)
Defogger
6 - 20 Amp (Yellow)
Heater
7 - 15 Amp (Light Blue)
Stoplights
8 - 15 Amp (Light Blue)
Horn, Wiper, Washer
9 - 10 Amp (Red)
Rear Wiper, Rear Washer
10 - 15 Amp (Light Blue)
Cigarette Lighter, Radio
CAUTIONS & WARNINGS
RADIATOR FAN & CAP
DO NOT loosen or remove radiator cap when cooling system is
hot. The system is under high pressure, and hot steam or boiling
liquid could gush out if cap is loosened or removed while system is
hot.
BRAKE FLUID
Be careful when handling brake fluid as it is harmful to eyes
and may damage painted surfaces.
REPLACING BLOWN FUSE
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.

GEN ER AL C O OLIN G S YSTE M S ER VIC IN G

1991 M it s u bis h i M onte ro
GENERAL INFORMATION
General Cooling System Servicing
* PLEASE READ THIS FIRST *
The following article is for general information only.
Information may not apply to all years, makes and models. See specific
article in the ENGINE COOLING section.
DESCRIPTION
The basic liquid cooling system consists of a radiator, water
pump, thermostat, electric or belt-driven cooling fan, pressure cap,
heater, and various connecting hoses and cooling passages in the block
and cylinder head.
MAINTENANCE
DRAINING
Remove radiator cap and open heater control valve to maximum
heat position. Open drain cocks or remove plugs in bottom of radiator
and engine block. In-line engines usually have one plug or drain cock,
while "V" type engines will have 2, one in each bank of cylinders.
CLEANING
A good cleaning compound removes most rust and scale. Follow
manufacturer's instructions in the use of cleaner. If considerable
rust and scale has to be removed, cooling system should be flushed.
Clean radiator air passages with compressed air.
FLUSHING
CAUTION: Some manufacturers use an aluminum and plastic radiator.
Flushing solution must be compatible with aluminum.
Back Flushing
Back flushing is an effective means of removing cooling
system rust and scale. The radiator, engine and heater core should be
flushed separately.
Radiator
To flush radiator, connect flushing gun to water outlet of
radiator and disconnect water inlet hose. To prevent flooding engine,
use a hose connected to radiator inlet. Use air in short bursts to
prevent damage to radiator. Continue flushing until water runs clear.
Engine
To flush engine, remove thermostat and replace housing.
Connect flushing gun to water outlet of engine. Flush using short air
bursts until water runs clean.
Heater Core
Flush heater core as described for radiator. Ensure heater
control valve is set to maximum heat position before flushing heater.

REFILLING
To prevent air from being trapped in engine block, engine
should be running when refilling cooling system. After system is full,
continue running engine until thermostat is open, then recheck fill
level. Do not overfill system.
TESTING
THERMOSTAT
1) Visually inspect thermostat for corrosion and proper
sealing of valve and seat. If okay, suspend thermostat and thermometer
in a 50/50 mixture of coolant and water. See Fig. 1. Do not allow
thermostat or thermometer to touch bottom of container. Heat water
until thermostat just begins to open.
2) Read temperature on thermometer. This is the initial
opening temperature and should be within specification. Continue
heating water until thermostat is fully open and note temperature.
This is the fully opened temperature. If either reading is not to
specification, replace thermostat.
Fig. 1: Testing Thermostat in Anti-Freeze/Water Solution
PRESSURE TESTING
A pressure tester is used to check both radiator cap and

complete cooling system. Test components as follows, following tool
manufacturer's instructions.
Radiator Cap
Visually inspect radiator cap, then dip cap into water and
connect to tester. Pump tester to bring pressure to upper limit of cap
specification. If cap fails to hold pressure, replace cap.
Fig. 2: Testing Radiator Pressure Cap
Cooling System
1) With engine off, wipe radiator filler neck seat clean.
Fill radiator to correct level. Attach tester to radiator and pump
until pressure is at upper level of radiator rating.
2) If pressure drops, inspect for external leaks. If no leaks
are apparent, detach tester and run engine until normal operating
temperature is reached. Reattach tester and observe. If pressure
builds up immediately, a possible leak exists from a faulty head
gasket or crack in head or block.
NOTE: Pressure may build up quickly. Release any excess pressure
or cooling system damage may result.
3) If there is no immediate pressure build up, pump tester to
within system pressure range (on radiator cap). Vibration of gauge
pointer indicates compression or combustion leak into cooling system.
Isolate leak by shorting each spark plug wire to cylinder block. Gauge
pointer should stop or decrease vibration when leaking cylinder is
shorted.

Incorrect thermostat in cooling system. Improperly adjusted
temperature control cable. Clogged heater core fins. Faulty heater
control valve.
NO TEMPERATURE REGULATION
Clogged or stuck heater control valve. Incorrect installation
of heater control valve control cable. Incorrect adjustment of heater
control valve link.
NO VENTILATION
Incorrect adjustment of change-over dampers. Duct connection
loose.
TESTING
BLOWER MOTOR SWITCH TEST
Blower motor switch can be tested using an ohmmeter. Insert
test leads into appropriate connector terminals, and check continuity.
See BLOWER SWITCH CONTINUITY table. See Fig. 5 or 6.
BLOWER MOTOR SWITCH CONTINUITY TABLE









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Continuity Between
Switch Position Terminal Nos.
Montero
Low ................................ 1-2 & 1-7
Medium 1 ........................... 2-4 & 4-7
Medium 2 ........................... 2-5 & 5-7
High ............................... 2-6 & 6-7
1992 Montero
Low ................................ 1-8 & 3-5
Medium 1 ........................... 1-8 & 5-6
Medium 2 ...................... 1-4, 1-8 & 2-5
High .......................... 1-4, 1-8 & 5-7
Pickup & Ram-50
Low ........................... 1-2, 2-6 & 7-8
Medium 1 ...................... 1-3, 3-6 & 7-8
Medium 2 ...................... 1-4, 4-6 & 7-8
High .......................... 1-5, 5-6 & 7-8









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Fig. 5: Blower Motor Switch Connector Terminal ID (Pickup & Ram-50)
Courtesy of Mitsubishi Motor Sales of America.

Removal (Montero)
1) Move temperature control lever to WARM position. Drain
coolant from vehicle. Disconnect heater hoses from heater unit. See
Fig. 1.
2) Remove lap heater ducts. Remove hood release bracket.
Using screwdriver, release tabs and remove left and right demister
grilles. Remove glove box frame attaching screws, and remove glove
box. Remove passenger lap heater duct.
3) Using screwdriver and shop towel, carefully pry at top
center of instrument cluster cover, and remove cover. Remove 2 screws
at bottom of instrument panel and one bolt at top of instrument panel.
Gently pull instrument cluster out, and disconnect speedometer cable
and electrical connections. Remove instrument cluster.
4) Remove 4 screws, and disconnect electrical connections on
back of instrument cluster. Remove instrument cluster. Handle
instrument cluster carefully. Instrument cluster can be damaged if
dropped.
5) Remove center console knobs and side screw plugs. Remove
screws, disconnect electrical connections and remove console. Remove 6
bolts and console bracket (center dash reinforcement). Disconnect
radio connections while removing console bracket.
6) Remove horn pad and steering wheel retaining nut. Mark
steering wheel and steering shaft for reassembly reference. Using
steering wheel puller, remove steering wheel.
7) Using screwdriver, carefully pry out dash plug at upper
center of dash panel. Remove 3 upper dash mounting nuts, one upper
screw above steering column, and 2 lower mounting screws. Remove dash
panel.
8) Remove control cables at heater unit. Remove heater unit
attaching screws. Remove heater ducts. Remove heater unit. Remove
heater control lever arm.
9) Remove heater control valve cover. Remove heater pipe and
heater control valve. Disconnect control arm linkage. Remove control
arm. Remove heater core by moving it sideways.
Installation
1) To install, reverse removal procedure. Insert heater hoses
fully into pipes, and clamp securely to prevent leaks. Connect heater
hoses with 1-1.2" (25-30 mm) overlap on outlet.
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.
Removal (Pickup & Ram-50)
1) Disconnect battery ground cable. Place heater control
lever to far right. Drain coolant. Using trim stick, pry out hazard
switch and remove electrical connection. Remove 4 instrument cluster
cover screws, and remove cover. Remove 4 instrument cluster screws.
Tilt instrument cluster out, and disconnect speedometer cable and
electrical connections. Remove cluster.
2) Remove fuse box cover and fuse box assembly. Remove glove
box. Remove defroster air ducts. Disconnect heater control cables.
Using trim stick, pry under and remove speaker grilles. Remove clock
or coin box in center of dash. Remove center dash hole cover (located
above clock).
3) Remove 2 center support cover screws, and remove cover.
Remove shift knob and 6 console attaching screws. Remove console.
Ensure all electrical connections are free of dash panel. Remove 3 top
nuts, one bolt above steering column, and side and lower attaching

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