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Mitsubishi Montero (2004+). Manual - part 3

HOW TO USE THIS MANUAL

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GENERAL <BODY AND CHASSIS>

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ACX00860

(continued)

TROUBLESHOOTING GUIDELINES

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GENERAL <BODY AND CHASSIS>

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TROUBLESHOOTING GUIDELINES

M1001008800157

VERIFY THE COMPLAINT

• Make sure the customer's complaint and the ser-

vice writer's work order description are under-
stood before starting work.

• Make sure the correct operation of the system is

understood. Read the service manual description
to verify any aspect of normal system operation.

• Operate the system to see the symptoms. Look

for other symptoms that were not reported by the
customer, or on the work order, that may be
related to the problem.

DETERMINE POSSIBLE CAUSES

Compare the confirmed symptoms to the diagnostic
symptom indexes to get to the right diagnosis proce-
dure.
If the confirmed symptoms can not be found on any
symptom index, determine other possible causes.

• Analyze the system diagrams and list all possible

causes for the problem symptoms.

• Rank all these possible causes in order of proba-

bility, based on how much of the system they
cover, how likely they are to be the cause, and
how easy they will be to check. Be sure to take
experience into account. Consider the causes of
similar problems seen in the past. The list of
causes should be ranked in order from general to
specific, from most-likely to least-likely, and from
easy-to-check to hard-to-check.

FIND THE PROBLEM

After the symptoms have been confirmed, and prob-
able causes have been identified, the next step is to
make step-by-step checks of the suspected system
components, junctions, and links in logical order.
Use the diagnostic procedures in the service manual
whenever possible. Follow these procedures care-
fully to avoid missing an important step in the diagno-
sis sequence. It might be the skipped step that leads
to the solution of the problem.
If the service manual doesn't have step-by-step pro-
cedures to help diagnose the problem, come up with
a series of checks based on the ranked list of proba-
ble causes. Troubleshooting checks should be made
in the order that the list of causes was ranked:

• general to specific

• most-likely to least-likely

• easy-to-check to hard-to-check

REPAIR THE PROBLEM

When the step-by-step troubleshooting checks find a
fault, perform the proper repairs. Make sure to fix the
root cause of the problem, not just the symptom. Just
fixing the symptom, without fixing the root cause, will
cause the symptom to eventually return.

VERIFY THE REPAIR

After repairs are made, recheck the operation of the
system to confirm that the problem is eliminated.
Make sure to check the system thoroughly. Some-
times new problems are revealed after repairs have
been made.

HOW TO USE TROUBLESHOOTING/INSPECTION SERVICE

POINTS

M1001000200515

Troubleshooting of electronic control systems for
which the scan tool can be used follows the basic
outline described below. Even in systems for which
the scan tool cannot be used, part of these systems
still follow this outline.

TROUBLESHOOTING CONTENTS

1. STANDARD FLOW OF DIAGNOSTIC TROU-
BLESHOOTING
Troubleshooting strategy are shown.

2. SYSTEM OPERATION AND SYMPTOM
VERIFICATION TESTS
If verification of the symptoms is difficult, procedures
for checking operation and verifying symptoms are
shown.

3. DIAGNOSTIC FUNCTION
The following trouble code diagnosis are shown.

• How to read diagnostic trouble codes

• How to erase diagnostic trouble codes

• Input inspection service points

HOW TO USE TROUBLESHOOTING/INSPECTION SERVICE POINTS

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GENERAL <BODY AND CHASSIS>

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4. DIAGNOSTIC TROUBLE CODE CHART
If the scan tool displays a diagnostic trouble code,
retrieve an applicable inspection procedure accord-
ing to this chart.

5. SYMPTOM CHART
If there are symptoms, even though the results of
inspection using the scan tool show that all diagnos-
tic trouble codes are normal, inspection procedures
for each symptom will be found by using this chart.

6. DIAGNOSTIC TROUBLE CODE PROCEDURES
Indicates the inspection procedures corresponding to
each diagnostic trouble code. (Refer to

P.00-6

7. SYMPTOM PROCEDURES
Indicates the inspection procedures corresponding to
each symptoms classified in the Symptom Chart.
(Refer to

P.00-6

)

8. SERVICE DATA REFERENCE TABLE
Inspection items and normal judgment values have
been provided in this chart as reference information.

9. CHECK AT ECU TERMINALS
Terminal numbers for the ECU connectors, inspec-
tion items and standard values have been provided
in this chart as reference information.

Terminal Voltage Checks
1. Connect a needle-nosed wire probe to a voltmeter

probe.

CAUTION

Short-circuiting the positive (+) probe between a
connector terminal and ground could damage
the vehicle wiring, the sensor, the ECU, or all
three. Use care to prevent this!
2. Insert the needle-nosed wire probe into each of

the ECU connector terminals from the wire side,
and measure the voltage while referring to the
check chart.

NOTE: Measure voltage with the ECU connectors
connected.
You may find it convenient to pull out the ECU to
make it easier to reach the connector terminals.
Checks don't have to be carried out in the order
given in the chart.

3. If voltage readings differ from normal condition

values, check related sensors, actuators, and
wiring, then replace or repair.

4. After repair or replacement, recheck with the

voltmeter to confirm that the repair has corrected
the problem.

Terminal Resistance and Continuity Checks
1. Turn the ignition switch to the "LOCK" (OFF)

position.

2. Disconnect the ECU connector.

CAUTION

If resistance and continuity checks are per-
formed on the wrong terminals, damage to the
vehicle wiring, sensors, ECU, and/or ohmmeter
may occur. Use care to prevent this!
3. Measure the resistance and check for continuity

between the terminals of the ECU harness-side
connector while referring to the check chart.
NOTE: Checks don't have to be carried out in the
order given in the chart.

4. If the ohmmeter shows any deviation from the

Normal Condition value, check the corresponding
sensor, actuator and related electrical wiring, then
repair or replace.

5. After repair or replacement, recheck with the

ohmmeter to confirm that the repair has corrected
the problem.

10. INSPECTION PROCEDURES USING AN
OSCILLOSCOPE
When there are inspection procedures using an
oscilloscope, these are listed here.

HOW TO USE THE INSPECTION
PROCEDURES

The causes of many of problems occurring in electric
circuitry are generally the connectors, components,
the ECU and the harnesses between connectors, in
that order. These inspection procedures follow this
order. They first try to discover a problem with a con-
nector or a defective component.

HOW TO USE TROUBLESHOOTING/INSPECTION SERVICE POINTS

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GENERAL <BODY AND CHASSIS>

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ACX00861AH

(1) Relevant circuit(s) of the component which
the DTC indicates are described.

(3) Shows the location of the connector(s) from
the circuit(s) above.

(4) Explains about the operation principle of the
component or its relevant parts in that circuit.

B-48(B)

(2) For connector color, refer to GROUP 80A,
How to read configuration diagrams.

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