Mitsubishi Galant. Manual — part 681

SWS DIAGNOSIS

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-119

STEP 4. Check the taillight relay.

Q: Is the taillight relay in good condition?

YES : Go to Step 5.
NO : Replace it. The taillights should illuminate normally.

STEP 5. Check the taillight relay power supply circuit at
the taillight relay connector A-05X.
(1)Disconnect the taillight relay connector A-05X and measure

at the relay box side.

(2)Measure the voltages between terminal 3, 4 and ground.

Q: Are the voltages approximately 12 volts (battery

positive voltage)?
YES : Go to Step 8.
NO : Go to Step 6.

STEP 6. Check taillight relay connector A-05X for damage.
Q: Is taillight relay connector A-05X in good condition?

YES : Go to Step 7.
NO : Repair or replace it. Refer to GROUP 00E, Harness

Connector Inspection

P.00E-2

. The taillights should

illuminate normally.

BATTERY
VOLTAGE

TESTER
CONNECTION

SPECIFIED
CONDITION

Not applied

1

−

3

Continuity

1

−

Battery (

−

)

terminal,
3

−

Battery (+)

terminal

4

−

5

Continuity

1

2 3

4

5

1

3

4

5

ACX01544

1

2

3

4

5

ACX01590AC

CONNECTOR A-05X
(RELAY BOX SIDE)

AC003128 AF

CONNECTOR: A-05X

TAILLIGHT
RELAY

BATTERY

SWS DIAGNOSIS

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-120

STEP 7. Check the harness wire between taillight relay
connector A-05X and battery.
Q: Is the harness wire between taillight relay connector A-

05X and battery in good condition?
YES : There is no action to be taken.
NO : Repair it. The taillights should illuminate normally.

STEP 8. Check taillight relay connector A-05X and front-
ECU connector A-09X for damage.
Q: Are taillight relay connector A-05X and front-ECU

connector A-09X in good condition?
YES : Go to Step 9.
NO : Repair or replace them. Refer to GROUP 00E,

Harness Connector Inspection

P.00E-2

. The taillights

should illuminate normally.

STEP 9. Check the harness wire between taillight relay
connector A-05X and front-ECU connector A-09X.
Q: Is the harness wire between taillight relay connector A-

05X and front-ECU connector A-09X in good condition?
YES : Replace the front-ECU. The taillights should

illuminate normally.

NO : Repair it. The taillights should illuminate normally.

AC003128 AF

CONNECTOR: A-05X

TAILLIGHT
RELAY

BATTERY

AC003128 AE

A-09X

CONNECTORS: A-05X, A-09X

FRONT - ECU

A-05X

TAILLIGHT
RELAY

BATTERY

AC003128 AE

A-09X

CONNECTORS: A-05X, A-09X

FRONT - ECU

A-05X

TAILLIGHT
RELAY

BATTERY

SWS DIAGNOSIS

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-121

Inspection Procedure I-2: Headlight, taillight: Headlights (low-beam) do not illuminate.

Headlight Relay (low) Drive Circuit

AC004211

SWS DIAGNOSIS

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-122

CIRCUIT OPERATION

•

If the headlight switch signal from the column
switch turns on, the front-ECU makes the
headlights illuminate. Whenever the headlights
illuminate, the low-beam lights illuminate due to
the headlight dimmer switch automatic resetting
function.

•

If the SWS communication line is defective, the
low-beam headlights will illuminate by using other
signal line (headlight back-up circuit).

TECHNICAL DESCRIPTION (COMMENT)
The headlight relay (low), column switch or the front-
ECU may be defective.

NOTE: If only one of the headlights does not
illuminate, the light bulb may be burned out or the
harness wires between the light and the headlight
relay (low) may be defective. In this case, check the
circuit by referring to GROUP 90, Headlight

P.90-60

.

TROUBLESHOOTING HINTS

•

Malfunction of the headlight relay (low)

•

Malfunction of the column switch (turn-signal light
and lighting switch)

•

Malfunction of the front-ECU

•

Damaged harness wires or connectors

DIAGNOSIS

Required Special Tools:

•

MB991223: Test Harness Set

•

MB991502: Scan Tool (MUT-II)

•

MB991529: Diagnostic Trouble Code Check Harness

AC003128 AG

A-09X

CONNECTORS: A-08X, A-09X

FRONT - ECU

A-08X

HEADLIGHT
RELAY(LOW)

BATTERY

AC003129 AD

CONNECTORS: A-27, A-32

A-27

A-32

AC003089 AC

CONNECTOR: C-05

AC003078 AB

CONNECTOR: C-60

COLUMN SWITCH

AC003079 AB

CONNECTOR
BLOCK (LH)

CONNECTOR: C-66