Mitsubishi Galant 9G. Manual — part 319

HOW TO DIAGNOSE

TSB Revision

GENERAL <ELECTRICAL>

00E-10

CHECKING SWITCHES

M1001004800144

In a circuit diagram, a switch is shown in the idle state.
1. Normally open or normally closed switch

Switches are classified into those which open the circuit and
those which close the circuit when off.
Switches are shown in their normal state unless specified
otherwise.

2. Switch connection

This figure illustrates a complex switch. The continuity
between terminals at each position is as indicated in the
table below.

SWITCH
POSITION

TESTER
CONNECTION

SPECIFIED
CONNECTION

OFF

−

−

1st stage

1

−5−6

Continuity

2nd stage

1

−4−6

Continuity

3rd stage

1

−3−6

Continuity

4th stage

1

−2−6

Continuity

ACX00944AC

CURRENT
FLOWS

CURRENT DOES
NOT FLOW

CURRENT DOES
NOT FLOW

CURRENT FLOWS

OFF

OFF

ON

ON

NORMALLY OPEN (NO) TYPE

NORMALLY CLOSED (NC) TYPE

ACX00945 AB

6

OFF

5

4

3

2

1

1ST 2ND 3RD 4TH STAGE

HOW TO DIAGNOSE

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GENERAL <ELECTRICAL>

00E-11

CHECKING RELAYS

M1001004900152

1. By using a relay, a heavy current can be turned on and off by

a switch using much less current. For example, in the circuit
shown here, when the switch is turned on (closed), current
flows to the coil of the relay. Then, its contact is turned on
(closed) and the light comes on. The current flowing through
the switch is much less than that for the light.

2. When current flows through the coil of a relay, its core is

magnetized to attract the iron piece, closing (ON) the
contact at the tip of the iron piece. When the coil current is
turned off, the iron piece returns to its original position by a
spring, opening the contact (OFF).

3. Relays may be classified as the normally open-type or the

normally closed-type, depending on their contact
construction.
NOTE: The deenergized state means that no current is flow-
ing through the coil. The energized state means that current
is flowing through the coil.

(1) The normally open-type

When a normally open relay as illustrated here is
checked, there should be no continuity between terminals
3 and 4 when the relay is deenergized. There should be
continuity between terminals 3 and 4 when battery
voltage and ground are applied to terminals 1 and 2. The
relay condition is determined by this check.
NOTE: Check the relay in both situation which is ener-
gized and is not energized.

(2) The normally closed-type

When a normally closed relay as illustrated here is
checked, there should be continuity between terminals 3
and 4 when the relay is deenergized. There should be no
continuity between terminals 3 and 4 when battery
voltage and ground are applied to terminals 1 and 2. The
relay condition is determined by this check.
NOTE: Check the relay in both situation which is ener-
gized and is not energized.

ACX00948 AB

POWER SUPPLY

FUSE

LIGHT

RELAY

SWITCH
ON

OFF

ON

OFF

AC308621 AB

COVER

SPRING

IRON
CORE

COIL

IRON
PIECE

CONTACT

NORMALLY OPEN (NO) TYPE

ENERGIZED STATE

AC310636 AB

NORMALLY OPEN (NO) TYPE

DEENERGIZED STATE ENERGIZED STATE

CURRENT FLOWS

CURRENT DOES
NOT FLOW

4

3

2

1

4

3

2

1

AC310637 AB

4

3

2

1

4

3

2

1

NORMALLY CLOSED (NC) TYPE

DEENERGIZED STATE ENERGIZED STATE

CURRENT FLOWS

CURRENT DOES
NOT FLOW

HOW TO DIAGNOSE

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GENERAL <ELECTRICAL>

00E-12

CABLES AND WIRES CHECK

M1001005100041

1. Check connections for looseness, rust, and stains.
2. Check terminals and wires for corrosion.
3. Check terminals and wires for open circuit or impending

open circuit.

4. Check wire insulation and coating for damage, cracks, and

wear.

5. Check conductive parts of terminals for contact with other

metallic parts (vehicle body and other parts).

6. Check grounding parts to verify that there is complete

continuity between attaching bolt(s) and vehicle body.

7. Check for incorrect wiring.
8. Check that harnesses are secured to prevent contact with

sharp edges and corners or hot parts (exhaust manifold,
pipe, etc.).

9. Check that harnesses are secured firmly to provide enough

clearance from the fan pulley, fan belt, and other rotating or
moving parts.

10.Check that the harnesses between fixed parts (such as the

vehicle body) and vibrating parts (such as the engine) are
long enough to allow for vibration and movement.

BATTERY HANDLING

M1001005200048

WARNING

Battery posts, terminals and related accessories con-
tain lead and lead compounds. WASH HANDS AFTER
HANDLING.

When checking or servicing does not require power from the
vehicle battery, be sure to disconnect the cable from the battery
(

−) terminal. This will prevent problems that could be caused by

a short circuit. Disconnect the (

−) battery terminal first and

reconnect it last.

GENERAL ELECTRICAL SYSTEM CHECK

M1001005300045

A circuit consists of the power supply, switch, relay, load,
ground, etc. There are various methods to check a circuit
including an overall check, voltage check, short-circuit check,
and continuity check. Each of the methods briefly described
below applies only to circuits similar to the illustration.

ACX00954 AB

ACX00955 AB

AC000017

HOW TO DIAGNOSE

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GENERAL <ELECTRICAL>

00E-13

1. VOLTAGE CHECK

(1) Ground one lead wire of the test light. If a voltmeter is

used instead of the test light, ground the grounding side
lead wire.

(2) Connect the other lead wire of the test light to the power

side terminal of the switch connector. The test light
should come on or the voltmeter should indicate a
voltage.

(3) Then, connect the test light or voltmeter to the motor

connector. The test light should not come on, or the
voltmeter should indicate no voltage. When the switch is
turned ON in this state, the test light should come on, or
the voltmeter should indicate a voltage, with the motor
starting to run.

(4) The circuit illustrated here is normal. If there is any

problem, such as the motor failing to run, check voltages
beginning at the connector nearest to the motor until the
faulty part is identified.

2. SHORT-CIRCUIT CHECK

Because the fuse has blown, it is probable that there is a
short circuit. Follow the procedures below to narrow down
the short-circuit location.

STEP 1. Remove the blown fuse and connect the test light
across the fuse terminals (Circuit switch: OFF).
Q: Does the test light illuminate?

YES : Short-circuit exists between the fuse block and the

switch. Repair the harness between the fuse block
and the switch.

NO : Go to Step 2.

ACX00956 AB

POWER SUPPLY

FUSE

SWITCH

MOTOR

(3)

ON (2)

OFF

(1)

TEST LIGHT
(OR
VOLTMETER)

ACX00957 AB

POWER SUPPLY

SWITCH

OFF

ILLUMINATION
LIGHT

TEST
LIGHT

FUSE BLOCK
(REMOVE
THE FUSE)

SHORT-CIRCUIT
LOCATION