Mitsubishi Lancer (4A9 engine). Manual - part 112

HEADLAMP

CHASSIS ELECTRICAL

54A-110

COMMENTS ON TROUBLE SYMPTOM
If both headlamps (low-beam) do not illuminate nor-
mally, the headlamp switch input circuit, headlamp
relay (LO), or ETACS-ECU may have a problem.

PROBABLE CAUSES

• Malfunction of column switch

• Malfunction of headlamp relay (LO)

• Malfunction of the ETACS-ECU

• Damaged harness wires and connectors

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III diagnosis code
Check if diagnosis code is set to the ETACS-ECU.

Q: Is the diagnosis code set?

YES :

Troubleshoot the ETACS-ECU. Refer to .

NO :

Go to Step 2.

STEP 2. M.U.T.-III data list
Use the ETACS-ECU service data to check the sig-
nal related to the operation of headlamp function.

• Headlamp switch to ON.

OK: Normal condition is displayed.

Q: Is the check result normal?

YES :

Go to Step 3.

NO :

Troubleshoot the ETACS-ECU. Refer to
Inspection Procedure 11 "The column
switch signal is not received" .

STEP 3. Connector check: A-28X Headlamp relay
(LO) connector

Q: Is the check result normal?

YES :

Go to Step 4.

NO :

Repair the defective connector.

STEP 4. Headlamp relay (LO) check
Refer to .

Q: Is the check result normal?

YES :

Go to Step 5.

NO :

Replace the headlamp relay (LO).

STEP 5. Voltage measurement at the A-28X
headlamp relay (LO) connector
(1) Remove the headlamp relay (LO), and measure

at the relay box side.

(2) Measure the voltage between headlamp relay

(LO) connector terminal No. 2/4 and the body
earth.

OK: System voltage

Q: Is the check result normal?

YES :

Go to Step 6.

NO :

Go to Step 8.

STEP 6. Connector check: C-312 ETACS-ECU
connector

Q: Is the check result normal?

YES :

Go to Step 7.

NO :

Repair the defective connector.

STEP 7. Wiring harness check between the A-28X
headlamp relay (LO) connector terminal No. 1
and the C-312 ETACS-ECU connector terminal
No. 6

• Check the output lines for open circuit or short

circuit.

Q: Is the check result normal?

YES :

Go to Step 9.

NO :

Repair the wiring harness.

STEP 8. Wiring harness check between the A-28X
headlamp relay (LO) connector terminal No. 2/4
and the fusible link (36) <Except 1800-DIESEL>
or (38) <1800-DIESEL>

• Check the output lines for open circuit or short

circuit.

Q: Is the check result normal?

YES :

Go to Step 9.

NO :

Repair the wiring harness.

STEP 9. Retest the system
Check that the headlamps (low-beam) illuminate nor-
mally.

Q: Is the check result normal?

Item No.

Item name

Normal
condition

Item 341

Head lamp switch

ACA00887

Connector: C-312 <RHD>
ETACS-ECU

HEADLAMP

CHASSIS ELECTRICAL

54A-111

YES :

The trouble can be an intermittent

malfunction (Refer to GROUP 00

− How to

use Troubleshooting/inspection Service
Points

− How to Cope with Intermittent

Malfunction ).

NO :

Replace the ETACS-ECU.

Inspection Procedure 2: None of the high-beam headlamps illuminate.

CAUTION

Whenever the ECU is replaced, ensure that the power source circuit, the earth circuit and the commu-
nication circuit are normal.

ETACS-ECU

HEADLAMP
RELAY (HI)

Wire colour code
B : Black LG : Light green G : Green L : Blue W : White Y : Yellow SB : Sky blue
BR : Brown O : Orange GR : Grey R : Red P : Pink V : Violet PU : Purple SI : Silver

ENGINE
COMPARTMENT

RELAY BOX

NOTE

:EXCEPT 1800-DIESEL
:1800-DIESEL

FUSIBLE
LINK

Headlamp Relay (High-Beam) Circuit

HEADLAMP

CHASSIS ELECTRICAL

54A-112

COMMENTS ON TROUBLE SYMPTOM
If both headlamps (high-beam) do not illuminate nor-
mally, the headlamp switch input circuit, headlamp
relay (HI), or ETACS-ECU may have a problem.

PROBABLE CAUSES

• Malfunction of column switch

• Malfunction of headlamp relay (HI)

• Malfunction of the ETACS-ECU

• Damaged harness wires and connectors

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III diagnosis code
Check if diagnosis code is set to the ETACS-ECU.

Q: Is the diagnosis code set?

YES :

Troubleshoot the ETACS-ECU. Refer to .

NO :

Go to Step 2.

STEP 2. M.U.T.-III data list
Use the ETACS-ECU service data to check the sig-
nal related to the operation of headlamp function.

• Headlamp switch to ON.

OK: Normal condition is displayed.

Q: Is the check result normal?

YES :

Go to Step 3.

NO :

Troubleshoot the ETACS-ECU. Refer to
Inspection Procedure 11 "The column
switch signal is not received" .

STEP 3. Connector check: A-19X headlamp relay
(HI) connector

Q: Is the check result normal?

YES :

Go to Step 4.

NO :

Repair the defective connector.

STEP 4. Headlamp relay (HI) check
Refer to .

Q: Is the check result normal?

YES :

Go to Step 5.

NO :

Replace the headlamp relay (HI).

STEP 5. Voltage measurement at the A-19X
headlamp relay (HI) connector
(1) Remove the headlamp relay (HI), and measure at

the relay box side.

(2) Measure the voltage between headlamp relay

(HI) connector terminal No. 2/4 and the body
earth.

OK: System voltage

Q: Is the check result normal?

YES :

Go to Step 6.

NO :

Go to Step 8.

STEP 6. Connector check: C-312 ETACS-ECU
connector

Q: Is the check result normal?

YES :

Go to Step 7.

NO :

Repair the defective connector.

AC612144

AC801941

Connector: A-19X

ACA00886

Connector: C-312 <LHD>
ETACS-ECU

ACA00887

Connector: C-312 <RHD>
ETACS-ECU

Item No.

Item name

Normal
condition

Item 341

Head lamp switch

HEADLAMP

CHASSIS ELECTRICAL

54A-113

STEP 7. Wiring harness check between the A-19X
headlamp relay (HI) connector terminal No. 1 and
the C-312 ETACS-ECU connector terminal No. 13

• Check the output lines for open circuit or short

circuit.

Q: Is the check result normal?

YES :

Go to Step 9.

NO :

Repair the wiring harness.

STEP 8. Wiring harness check between the A-19X
headlamp relay (HI) connector terminal No. 2/4
and the fusible link (36) <Except 1800-DIESEL>
or (38) <1800-DIESEL>

• Check the power source line for open circuit or

short circuit.

Q: Is the check result normal?

YES :

Go to Step 9.

NO :

Repair the wiring harness.

STEP 9. Retest the system
Check that the headlamps (high-beam) illuminate
normally.

Q: Is the check result normal?

YES :

The trouble can be an intermittent

malfunction (Refer to GROUP 00

− How to

use Troubleshooting/inspection Service
Points

− How to Cope with Intermittent

Malfunction ).

NO :

Replace the ETACS-ECU.

Inspection Procedure 3: The headlamps (low-beam) illuminate regardless of the lighting switch
positions. (High-beam does not illuminate)

CAUTION

Whenever the ECU is replaced, ensure that the
power supply circuit, the earth circuit and the
communication circuit are normal.
COMMENTS ON TROUBLE SYMPTOM
If the headlamps illuminate only at low-beam regard-
less of the lighting switch position, the headlamp fail-
safe function may be active.

PROBABLE CAUSES

• Malfunction of column switch

• Malfunction of the lighting control sensor <Vehi-

cles with auto lamp function>

• Malfunction of the ETACS-ECU

• Damaged harness wires and connectors

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III diagnosis code
Check if diagnosis code is set to the ETACS-ECU.

Q: Is the diagnosis code set?

YES :

Troubleshoot the ETACS-ECU. Refer to .

NO :

Go to Step 2.

STEP 2. M.U.T.-III other system diagnosis code
Check if diagnosis code is set to the LIN.

Q: Is the diagnosis code set?

YES :

Refer to diagnosis code chart .

NO :

Go to Step 3.

STEP 3. M.U.T.-III data list
Use the ETACS-ECU service data to check the sig-
nals related to the operation of auto lamp function.

• Headlamp switch to ON.

• Turn the lighting switch to the "AUTO" position

<Vehicles with auto lamp function>.

OK: Normal condition is displayed.

Q: Is the check result normal?

YES <Vehicles without auto lamp function> :

Go to

Step 5.

YES <Vehicles with auto lamp function> :

Go to

Step 4.

NO :

Troubleshoot the ETACS-ECU. Refer to
Inspection Procedure 11 "The column
switch signal is not received" .

STEP 4. Check that the auto lamp function.
Check that the auto lamp function normally (Refer to
).

Q: Is the check result normal?

Item No.

Item name

Normal
condition

Item 341

Head lamp switch

Item No.

Item name

Normal
condition

Item 348

Head lamp switch
(auto)

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