Mitsubishi 380. Manual — part 226

HARNESS CONNECTOR INSPECTION

GENERAL <ELECTRICAL>

00E-2

HARNESS CONNECTOR INSPECTION

M1001003900201

CONNECTOR CONTINUITY AND VOLTAGE TEST

Required Special Tools:

• MB991219: Test Harness Set

• MD998459: Test Harness

Follow the steps below to avoid causing poor connector contact
and/or reduced waterproof performance of connectors when
checking continuity and/or voltage at waterproof connectors.

CAUTION

Never backtest probe a waterproof connector. Backprob-
ing a connector may cause the terminals to corrode, dete-
riorating circuit performance.
1. If the circuit to be checked is a closed state, use a special

tool like MD998459.

CAUTION

Forcing the test probe into the terminal may open the ter-
minal, causing intermittent or poor contact and creating an
open circuit.
2. If the connector is disconnected for checking and the facing

part is the female pin side, use an appropriate male terminal
for checking the contact pressure of connector pins (like
MB991219).

CAUTION

Do not simultaneously contact more than one terminal
with the test probe. Contacting two or more terminals at
the same time may damage a circuit, possibly to the point
of starting an electrical fire.
3. If the facing part is the male pin side, either carefully touch

the test probe to the pin so it does not accidently contact
other pins, or use an appropriate female terminal.

HOW TO DIAGNOSE

HOW TO DIAGNOSE

M1001004300086

The most important point in troubleshooting is to
determine "Probable Cause." Once the probable
causes are determined, parts to be checked can be
limited to those associated with such probable
causes. The determination of the probable causes
must be based on a theory and be supported by facts
and must not be based on intuition only.

AC000014

AB

MD998459

AC000015

AB

MB991219

HOW TO DIAGNOSE

GENERAL <ELECTRICAL>

00E-3

TROUBLESHOOTING STEPS

M1001004400049

If an attempt is made to solve a problem without going through correct steps for troubleshooting, the symp-
toms could become more complicated, resulting in failure to determine the causes correctly and making
incorrect repairs. The four steps below should be followed in troubleshooting.

INFORMATION FOR DIAGNOSIS

M1001004500132

This manual contains the harness diagrams as well as the individual circuit drawings, operational explana-
tions, and troubleshooting hints for each component. The information is presented in the following manner:

1. Connector diagrams show the connector

positions, etc., on the actual vehicle as well as the
harness path.

2. Circuit diagrams show the configuration of the

circuit with all switches in their normal positions.

3. Operational explanations include circuit drawings

of current flow when the switch is operated and
how the component reacts.

4. Troubleshooting hints include numerous

examples of problems which might occur, traced
backward in a common-sense manner to the
origin of the trouble. Problems whose origins may
not be found in this manner are pursued through
the various system circuits.

NOTE: Components of MPI, ETACS, etc. with ECU do not include 3 and 4 above. For this information, refer
to a relevant group which includes details of these components.

00DB087A

3

Checking of Parts Associated with

Probable Causes and Determination

of Faulty Parts

2 Determination of Probable Causes

4 Confirmation

Observe the symptom carefully. Check if there are also

other problems.

In determining the probable causes, it is necessary to

study the wiring diagram to understand the circuit as a

system. Knowledge of switches, relays and other parts is

necessary for accurate analysis. The causes of similar

problems in the past must be taken into account.

Troubleshooting is carried out by making step-by-step

checks until the cause is found.

After the problems are corrected, be sure to check that the

system operates correctly.

1 Observation of Problem Symptoms

HOW TO DIAGNOSE

GENERAL <ELECTRICAL>

00E-4

INSPECTION

M1001004600139

1. Sight and sound checks

Check relay operation, blower motor rotation, light
illumination, etc. Listen for a "click" when some relay covers
are pushed down.

2. Simple checks

For example, if a headlight does not come on and a faulty
fuse or poor grounding is suspected, replace the fuse with a
new one. Or use a jumper wire to ground the light to the
body. Determine which part(s) is/are responsible for the
problem.

3. Checking with instruments

Use an appropriate instrument in an adequate range and
read the indication correctly.

ACX00936 AB

CLICK

ACX00937

ACX00938AB

SELECTOR KNOB

POINTER

HOW TO DIAGNOSE

GENERAL <ELECTRICAL>

00E-5

INSPECTION INSTRUMENTS

M1001004700040

For inspection, use the following instruments:

CAUTION

Never use a test light for checking ECU-related circuits or
ECUs.
1. Test light

A test light consists of a 12V bulb and lead wires. It is used
to check voltages or short circuits.

2. Self-powered test light

A self-powered test light consists of a bulb, battery and lead
wires connected in series. It is used to check continuity or
grounding.

CAUTION

Never use a jumper wire to connect a power supply
directly to a load.
3. Jumper wire

A jumper wire is used to close an open circuit.

4. Voltmeter

A voltmeter is used to measure the circuit voltage. Normally,
the positive (red lead) test probe is applied to the point of
voltage measurement and the negative (black lead) test
probe to the body ground. Use a digital voltmeter to check
for voltage drop before or after a component.

ACX00939

ACX00940

ACX00941

ACX00942AB

RED LEAD WIRE

POWER LINE

BLACK LEAD WIRE

GROUND