break MITSUBISHI MONTERO 1991 Owner's Guide

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Page 1071 of 1333

MITSUBISHI MONTERO 1991 Owners Guide 2. ENGINE IGNITION TIMING - Must be set with timing terminal
grounded.
3. ENGINE VACUUM - Must be normal for your altitude.
4. ENGINE VALVE TIMING - To specifications.
5. ENGINE COMPRESSION -

Page 1146 of 1333

MITSUBISHI MONTERO 1991 Owners Guide motor to increase idle speed. To prevent A/C compressor from switching
on before idle speed has increased, ECU momentarily opens A/C relay
circuit.
Idle Speed Control (ISC) Motor
Con

motor to increase idle speed. To prevent A/C compressor from switching
on before idle speed has increased, ECU momentarily opens A/C relay
circuit.
Idle Speed Control (ISC) Motor
Controls pintle-type air valve (DOHC engines) or throttle
plate angle (SOHC engines) to regulate volume of intake air at idle.
During start mode, ECU controls idle intake air volume
according to coolant temperature input. After starting, with idle
position switch activated (throttle closed), fast idle speed is
controlled by ISC motor and fast idle air control valve (if equipped).\
When idle switch is deactivated (throttle open), ISC motor
moves to a preset position in accordance with coolant temperature
input.
When automatic transmission (if equipped) is shifted from
Neutral to Drive, A/C is turned on or power steering pressure reaches
a preset value, ECU signals ISC motor to increase engine RPM.
Fast Idle Air Control Valve
Some models use a coolant temperature-sensitive fast idle air
control valve, located on throttle body, to admit additional intake
air volume during engine warm-up. Control valve closes as temperature
increases, restricting by-pass airflow rate. At engine warm-up, valve
closes completely.
IGNITION SYSTEMS
DIRECT IGNITION SYSTEM (DIS) - DOHC ENGINES
Ignition system is a 2-coil, distributorless ignition system.
Crankshaft angle and TDC sensor assembly, mounted in place of
distributor, are optically controlled.
Power Transistors & Ignition Coils
Based on crankshaft angle and TDC sensor inputs, ECU controls
timing and directly activates each power transistor to fire coils.
Power transistor "A" controls primary current of ignition coil "A" to
fire spark plugs on cylinders No. 1 and 4 at the same time. Power
transistor "B" controls primary current of ignition coil "B" to fire
spark plugs on cylinders No. 2 and 3 at the same time.
Although each coil fires 2 plugs at the same time, ignition
takes place in only one cylinder since the other cylinder is on its
exhaust stroke when plug fires.
ELECTRONIC IGNITION SYSTEM - SOHC ENGINES
Mitsubishi breakerless electronic ignition system uses a disc
and optical sensing unit to trigger power transistor.
Power Transistor & Ignition Coil
Power transistor is mounted inside distributor with disc and
optical sensing unit. When ignition is on, ignition coil primary
circuit is energized. As distributor shaft rotates, disc rotates,
triggering optical sensing unit. ECU receives signals from optical
sensing unit. Signals are converted and sent to power transistor,
interrupting primary current flow and inducing secondary voltage.
IGNITION TIMING CONTROL SYSTEM
Ignition timing is controlled by ECU. ECU adjusts timing
based upon various conditions, such as engine temperature, altitude
and detonation (turbo vehicles only).

Page 1149 of 1333

$MITSUBISHI MONTERO 1991 Owners Guide \003 TR AIL E R H IT C H W ELD C AN B REA K : N EW T R AIL E R H IT C H 1991 M it s u bis h i M onte ro NHTSA RECALL BULLETIN Models: 1986 Isuzu Trooper II$

\003
TR AIL E R H IT C H W ELD C AN B REA K : N EW T R AIL E R H IT C H

1991 M it s u bis h i M onte ro
NHTSA RECALL BULLETIN
Models: 1986 Isuzu Trooper II
1987 Dodge Raider
1987 Isuzu Trooper II
1988 Dodge Raider
1988 Isuzu Trooper II
1989 Dodge Raider
1989 Isuzu Amigo
1989 Isuzu Trooper II
1990 Isuzu Amigo
1990 Isuzu Trooper
1991 Isuzu Amigo
1991 Isuzu Trooper
1991 Mitsubishi Montero
1991 Toyota Land Cruiser
1992 Mitsubishi Montero
1992 Toyota Land Cruiser
1993 Toyota Land Cruiser
Number of Affected Vehicles: 670
Beginning Date of Manufacture: 1992 MAR
Ending Date of Manufacture: 1993 JUN
FAULT:
Weld, Solder broken
SYSTEM:
Trailer hitch.
EQUIPMENT DESCRIPTION:
Reese class II trailer hitch, Part No. 06070.
DESCRIPTION OF DEFECT:
The weld on the receiver unit of the trailer hitch can break.
CONSEQUENCE OF DEFECT:
If the failure occurs, the trailer can separate from the towing
vehicle, and could result in a vehicle crash without warning.
CORRECTIVE ACTION:
Replace the trailer hitch.
NOTE:
If your vehicle is presented to the dealer from whom you purchased the
item on an agreed service date and the remedy is not provided or the
remedy does correct the safety-related defect or noncompliance, please
contact Reese Products warranty department at 1-800-326-1090, ext.
203. Also contact the National Highway Traffic Safety Administration's
auto safety hotline at 1-800-424-9393.
ADDITIONAL INFORMATION:
The National Highway Traffic Safety Administration operates Monday

Page 1224 of 1333

$MITSUBISHI MONTERO 1991 Owners Guide ignition switch Open circuit between Repair circuit ignition switch and starter solenoid ��\ ��$

ignition switch
Open circuit between Repair circuit
ignition switch and
starter solenoid
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Engine Runs Fuel lines leaking or Tighten fitting,
Rough clogged remove restriction
Initial timing incorrect Reset ignition timing
see ENGINE PERFORMANCE
Centrifugal advance Repair distributor
malfunction advance
Defective spark plugs or Replace plugs or plug
wiring wiring
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Component Failure Spark arc-over on cap, Replace cap, rotor or
rotor or coil or coil
Defective pick-up coil Replace pick-up coil
Defective ignition coil Replace ignition coil
Defective vacuum unit Replace vacuum unit
Defective control module Replace control module
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BASIC ELECTRONIC IGNITION TROUBLE SHOOTING
CHARTS - USING OSCILLOSCOPE PATTERNS
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CONDITION POSSIBLE CAUSE CORRECTION\
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Firing Voltage Retarded ignition timing Reset ignition
Lines are the Same, timing, see ENGINE
but Abnormally High PERFORMANCE section
Fuel mixture too lean Readjust carburetor,
see ENGINE PERFORMANCE
High resistance in coil Replace coil wire
wire
Corrosion in coil tower Clean and/or replace
terminal coil
Corrosion in distributor Clean and/or replace
coil terminal distributor cap
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Firing Voltage Fuel mixture too rich Readjust carburetor,
Lines are the Same see ENGINE PERFORMANCE
but Abnormally Low
Breaks in coil wire causing Replace coil wire
arcing
Cracked coil tower causing Replace coil
arcing
Low coil output Replace coil
Low engine compression Determine cause and

Page 1225 of 1333

$MITSUBISHI MONTERO 1991 Owners Guide repair��\ ��\ ��\ ��\ ��\ ��\ ��\ ��$

repair\
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One or More, But Carburetor idle mixture Readjust carburetor,
Not All Firing not balanced see ENGINE PERFORMANCE
Voltage Lines are
Higher Than Others EGR valve stuck open Clean and/or replace
valve
High resistance in spark Replace spark plug
plug wires wires
Cracked or broken spark Replace spark plugs
plug insulator
Intake vacuum leak Repair leak
Defective spark plugs Replace spark plugs
Corroded spark plug Replace spark plugs
terminals
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One or More, But Curb idle mixture not Readjust carburetor,
Not All Firing balanced see ENGINE PERFORMANCE
Voltage Lines Are
Lower Than Others Breaks in plug wires Replace plug wires
causing arcing
Cracked coil tower causing Replace coil
arcing
Low compression Determine cause and
repair
Defective spark plugs Replace spark plugs
Corroded spark plugs Replace spark plugs
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Cylinders Not Cracked distributor cap Replace distributor
Firing terminals cap
Shorted spark plug wire Determine cause and
repair
Mechanical problem in Determine cause and
engine repair
Defective spark plugs Replace spark plugs
Spark plugs fouled Replace spark plugs
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BASIC DRIVEABILITY PROBLEMS TROUBLE SHOOTING TABLE\
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CONDITION POSSIBLE CAUSE CORRECTION\
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Hard Starting Binding carburetor linkage Eliminate binding
Binding choke linkage Eliminate binding
Binding choke piston Eliminate binding
Restricted choke vacuum Check vacuum lines
for blockage

Page 1269 of 1333

MITSUBISHI MONTERO 1991 Owners Guide the types of injector circuits that your noid lights are designed for.
There are three. They are:
* Systems with a voltage controlled injector driver. Another
way to say it: The noid l

the types of injector circuits that your noid lights are designed for.
There are three. They are:
* Systems with a voltage controlled injector driver. Another
way to say it: The noid light is designed for a circuit with
a "high" resistance injector (generally 12 ohms or above).
* Systems with a current controlled injector driver. Another
way to say it: The noid light is designed for a circuit with
a low resistance injector (generally less than 12 ohms)
without an external injector resistor.
* Systems with a voltage controlled injector driver and an
external injector resistor. Another way of saying it: The
noid light is designed for a circuit with a low resistance
injector (generally less than 12 ohms) and an external
injector resistor.
NOTE: Some noid lights can meet both the second and third
categories simultaneously.
If you are not sure which type of circuit your noid light is
designed for, plug it into a known good car and check out the results.
If it flashes normally during cranking, determine the circuit type by
finding out injector resistance and if an external injector resistor
is used. You now know enough to identify the type of injector circuit.
Label the noid light appropriately.
Next time you need to use a noid light for diagnosis,
determine what type of injector circuit you are dealing with and
select the appropriate noid light.
Of course, if you suspect a no-pulse condition you could plug
in any one whose connector fit without fear of misdiagnosis. This is
because it is unimportant if the flashing light is dim or bright. It
is only important that it flashes.
In any cases of doubt regarding the use of a noid light, a
lab scope will overcome all inherent weaknesses.
OVERVIEW OF DVOM
A DVOM is typically used to check injector resistance and
available voltage at the injector. Some techs also use it check
injector on-time either with a built-in feature or by using the
dwell/duty function.
There are situations where the DVOM performs these checks
dependably, and other situations where it can deceive you. It is
important to be aware of these strengths and weaknesses. We will cover
the topics above in the following text.
Checking Injector Resistance
If a short in an injector coil winding is constant, an
ohmmeter will accurately identify the lower resistance. The same is
true with an open winding. Unfortunately, an intermittent short is an
exception. A faulty injector with an intermittent short will show
"good" if the ohmmeter cannot force the short to occur during testing.
Alcohol in fuel typically causes an intermittent short,
happening only when the injector coil is hot and loaded by a current
high enough to jump the air gap between two bare windings or to break
down any oxides that may have formed between them.
When you measure resistance with an ohmmeter, you are only
applying a small current of a few milliamps. This is nowhere near
enough to load the coil sufficiently to detect most problems. As a
result, most resistance checks identify intermittently shorted
injectors as being normal.
There are two methods to get around this limitation. The
first is to purchase an tool that checks injector coil windings under

Page 1320 of 1333

$MITSUBISHI MONTERO 1991 Owners Guide White .................. WHT ................... WT Yellow ................. YEL ................... YL ��\ ��\ ��\ ��\ ��$

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