Mitsubishi Galant (2004+). Manual - part 292

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-359

INSPECTION PROCEDURE H-7: Headlight and Taillight: One of the headlights does not illuminate. 
<4-bulb type>

HEADLIGHT
RELAY: HIGH

PULSE WIDTH 
MODULATOR

HEADLIGHT
(LOW: LH)

HEADLIGHT
(LOW: RH)

HEADLIGHT
(HIGH: LH)

HEADLIGHT
(HIGH: RH)

RELAY
BOX

FRONT-ECU

Headlights Circuit <4-bulb type>

AC305977AE

CONNECTOR: A-11X

AC305210

A-20 (BR)

A-21 (B)

CONNECTORS: A-20, A-21

AH

SYMPTOM PROCEDURES

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-360

.

TECHNICAL DESCRIPTION (COMMENT)
If one of the headlights does not illuminate, a head-
light bulb may be defective.

.

TROUBLESHOOTING HINTS

• The headlight bulb may be defective

• The wiring harness or connectors may have 

loose, corroded, or damaged terminals, or termi-
nals pushed back in the connector

.

DIAGNOSIS

Required Special Tool:

• MB991223: Harness Set

STEP 1. Check the headlight operation.
Q: Which of the headlights does not illuminate?

Low (LH) : Go to Step 2.
Low (RH) : Go to Step 8.
High (LH) : Go to Step 14.
High (RH) : Go to Step 20.
Low beam only (both RH and LH) : Refer to Inspection 

Procedure H-2 "The headlights (low-beam) do not 
illuminate normally 

P.54B-313

."

High beam only (both RH and LH) : Refer to Inspection 

Procedure H-3 "The headlights (high-beam) do not 
illuminate normally 

P.54B-318

."

High beam indicator light : Refer to Inspection Procedure 

H-8 "The high-beam indicator light does not illuminate 

P.54B-369

."

STEP 2. Check headlight (LOW: LH) connector A-20 for 
loose, corroded or damaged terminals, or terminals 
pushed back in the connector.

Q: Is headlight (LOW: LH) connector A-20 in good 

condition?
YES : Go to Step 3.
NO :  Repair or replace the damaged component(s). Refer 

to GROUP 00E, Harness Connector Inspection 

P.00E-2

. Check that the headlight (LOW: LH) 

illuminates normally.

AC305206

A-31 (B)

A-32 (BR)

CONNECTORS: A-31, A-32

AP

AC305210AN

CONNECTOR: A-20

A-20 (BR)

HARNESS SIDE

SYMPTOM PROCEDURES

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SIMPLIFIED WIRING SYSTEM (SWS)

54B-361

STEP 3. Check the headlight bulb (LOW: LH).

(1) Remove the headlight bulb (LOW: LH).
(2) Verify that the headlight bulb (LOW: LH) is not damaged or 

burned out.

Q: Is the headlight bulb (LOW: LH) in good condition?

YES : Go to Step 4.
NO :  Replace the headlight bulb (LOW: LH). Verify that the 

headlight (LOW: LH) illuminates normally.

STEP 4. Check the ground circuit to the headlight (LOW: 
LH). Measure the resistance at headlight (LOW: LH) 
connector A-20.

(1) Disconnect headlight (LOW: LH) connector A-20 and 

measure the resistance available at the wiring harness side 

of the connector.

(2) Measure the resistance value between terminal 2 and 

ground.

• The resistance should be 2 ohms or less.

Q: Is the measured resistance 2 ohms or less?

YES : Go to Step 6.
NO :  Go to Step 5.

STEP 5. Check the wiring harness between headlight 
(LOW: LH) connector A-20 (terminal 2) and ground.

Q: Is the wiring harness between headlight (LOW: LH) 

connector A-20 (terminal 2) and ground in good 
condition?
YES : Replace the headlight socket (LOW: LH). Verify that 

the headlight (LOW: LH) illuminates normally.

NO :  The wiring harness may be damaged or the 

connector(s) may have loose, corroded or damaged 
terminals, or terminals pushed back in the connector. 
Repair the wiring harness as necessary. Verify that 
the headlight (LOW: LH) illuminates normally.

AC305210AN

CONNECTOR: A-20

A-20 (BR)

HARNESS SIDE

AC209364GP

CONNECTOR A-20
(HARNESS SIDE)

AC305210AN

CONNECTOR: A-20

A-20 (BR)

HARNESS SIDE

SYMPTOM PROCEDURES

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SIMPLIFIED WIRING SYSTEM (SWS)

54B-362

STEP 6. Check front-ECU connector A-11X for loose, 
corroded or damaged terminals, or terminals pushed back 
in the connector.

Q: Is front-ECU connector A-11X in good condition?

YES : Go to Step 7.
NO :  Repair or replace the damaged component(s). Refer 

to GROUP 00E, Harness Connector Inspection 

P.00E-2

. Check that the headlight (LOW: LH) 

illuminates normally.

STEP 7. Check the wiring harness between headlight 
(LOW: LH) connector A-20 (terminal 1) and front-ECU 
connector A-11X (terminal 6).

Q: Is the wiring harness between headlight (LOW: LH) 

connector A-20 (terminal 1) and front-ECU connector 
A-11X (terminal 6) in good condition?
YES : No action is necessary and testing is complete.
NO :  The wiring harness may be damaged or the 

connector(s) may have loose, corroded or damaged 
terminals, or terminals pushed back in the connector. 
Repair the wiring harness as necessary. Verify that 
the headlight (LOW: LH) illuminates normally.

AC305977AH

CONNECTOR: A-11X

RELAY BOX SIDE 

AC305977AH

CONNECTOR: A-11X

RELAY BOX SIDE 

AC305210AN

CONNECTOR: A-20

A-20 (BR)

HARNESS SIDE