1991 MITSUBISHI MONTERO lock

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.

Fig. 6: Blower Motor Switch Connector Terminal ID (Montero)
Courtesy of Mitsubishi Motor Sales of America.
BLOWER MOTOR TEST
1) Turn ignition on. Check fuses. If fuses are bad, check
wiring harness for short circuits. If fuses are okay, check voltage
between heater relay and ground circuit. If voltage does not exist at
heater relay, check for broken wire between fuse block and heater
relay.
2) If voltage exists at heater relay, check relay, and
replace if necessary. See BLOWER MOTOR RELAY TEST under TESTING. If
relay is okay, disconnect blower motor connector. Set heater switch to
either LO, MED or HI setting.
3) Check voltage between harness side of connector and
vehicle ground. Battery voltage should be present. If battery voltage
is present, go to next step. If battery voltage is not present, check
continuity between resistor terminals. See BLOWER MOTOR RESISTOR TEST
under TESTING. If continuity is not present, replace resistor.

4) If continuity is present between motor terminals at blower
connector, check ground circuit. If ground circuit is okay, check for
blower motor malfunction. Disconnect blower motor terminals. Connect
blower motor terminals directly to battery. Blower motor should
operate smoothly.
5) Reverse blower motor terminal polarity to battery. Blower
motor should operate smoothly in reverse direction. If blower motor
does not operate as specified, replace blower motor.
BLOWER MOTOR RELAY TEST
NOTE: Pickup and Ram-50 blower motors do not have blower motor
relays.
1) Remove blower motor relay from fuse/relay block. Connect
an ohmmeter between terminals No. 1 and 3. See Fig. 7. Continuity
should not be present.
2) Connect an ohmmeter between terminals No. 2 and 4.
Continuity should be present. Connect 12-volt battery positive lead to
terminal No. 2 and negative lead to terminal No. 4. See Fig. 7.
3) Connect an ohmmeter between terminals No. 1 and 3.
Continuity should be present. If continuity is not as specified in any
step, replace relay.
Fig. 7: Identifying Blower Relay Terminals
Courtesy of Mitsubishi Motor Sales of America.
BLOWER MOTOR RESISTOR TEST

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

WIRING DIAGRAM COMPONENT LOCATIONS
When trying to locate a component in a wiring diagram and you
don't know the specific system where it is located, use this handy
component locator to find the system wiring diagram in which the
component is located. Then, go to that system and locate the component
within the wiring diagram.
For example, if you don't know the specific system in which
the ignition switch is located, look up ignition switch in the wiring
diagram component location tables and go to the appropriate wiring
diagram(s) which contain either full or partial views of the ignition
switch. The full view of the ignition switch is located in Power
Distribution.
The first listing for the component will be the full or most
complete view of the component. Additional listings will be partial
views of the component. Not all components are used on all models.
All components will have a partial view in Ground
Distribution and Power Distribution. Data Link Connectors show
connecting circuits between modules. Alternate names for components
may be listed in wiring diagram component locations tables.
WIRING DIAGRAM COMPONENT LOCATIONS TABLE









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Component Wiring Diagram
ABS Electronic Control Unit ....................... Anti-Lock Brakes
Data Link Connectors
ABS Hydraulic Unit ................................ Anti-Lock Brakes
Acceleration Sensor ............................... Anti-Lock Brakes
Accessory Delay Relay ................................ Power Windows
A/C Compressor Clutch Relay ..................... Engine Performance
A/C Sensor ...................................... Engine Performance
A/C Pressure Switch ............................. Engine Performance
Adaptive Lamp Control Module ....................... Exterior Lights
Air Bag(s) ................................ Air Bag Restraint System\
Air Bag Module ............................ Air Bag Restraint System
Air Bag Sensor(s) ......................... Air Bag Restraint System\
Air Injection Pump Relay ........................ Engine Performance
Air Temperature Sensor ............................ Overhead Console
Alternator (Generator) ..................... Generators & Regulators\
Anti-Theft Control Module ........................ Anti-Theft System
Starters
Autolamp Control Relay ........................... Headlight Systems
Daytime Running Lights
Automatic Shutdown (ASD) Relay .................. Engine Performance\
Generators & Regulators
Autostick Switch ................................ Engine Performance
Auxiliary Battery Relay .................... Generators & Regulators
Back-Up Lights ...................................... Back-Up Lights
Exterior Lights
Barometric (BARO) Pressure Sensor ............... Engine Performance\
Battery ......................................... Power Distribution
Battery Temperature Sensor ...................... Engine Performance
Body Control Module .......................... Body Control Computer
Anti-Theft System
Daytime Running Lights
Engine Performance
Headlight Systems
Warning Systems
Boost Control Solenoid .......................... Engine Performance
Boost Sensor .................................... Engine Performance
Brake Fluid Level Switch .................. Analog Instrument Panels