INSPECTION PROCEDURE L-7: The headlamp(s) do not illuminate.


caution Whenever the ECU is replaced, ensure that the input and output signal circuits are normal.


COMMENTS ON TROUBLE SYMPTOM
If any of the headlamps does not illuminate, the wiring harness connector(s), the bulb or the fuse may be defective or burned out.

POSSIBLE CAUSES

  • Malfunction of the headlamp bulbs
  • Damaged harness wires and connectors

DIAGNOSIS PROCEDURE

Step 1. Connector check: A-35 head lamp (HI: RH) connector or A-21 head lamp (HI: LH) connector, A-38 head lamp (LO: RH) connector or A-18 head lamp (LO: LH) connector.




Q. Is the check result normal?

Go to Step 2.

Repair the defective connector.

Step 2. Check the bulbs of the head lamp.
Check the bulb of the lamp which does not illuminate.

Q. Is the check result normal?
Go to Step 3.
Replace the bulb of the lamp which does not illuminate.

Step 3. Resistance measurement at the A-35 head lamp (HI: RH) connector or A-21 head lamp (HI: LH) connector, A-38 head lamp (LO: RH) connector or A-18 head lamp (LO: LH) connector.




(1)Disconnect the connector, and measure at the wiring harness side.


(2)Check the resistance between the lamp connector and body earth.

  • Resistance between A-35 headlamp (HI: RH) connector terminal No.2 and body earth
  • Resistance between A-21 headlamp (HI: LH) connector terminal No.2 and body earth
  • Resistance between A-38 headlamp (LO: RH) connector terminal No.1 and body earth
  • Resistance between A-18 headlamp (LO: LH) connector terminal No.1 and body earth
OK: 2 Ω or less

Q. Is the check result normal?

Go to Step 6.

Go to Step 4.

Step 4. Connector check: A-25 earth connector.


Q. Is the check result normal?

Go to Step 5.

Repair the defective connector.

Step 5. Check the wiring harness from A-35 head lamp (HI: RH) connector terminal No.2 or A-21 head lamp (HI: LH) connector terminal No.2, A-38 head lamp (LO: RH) connector terminal No.1 or A-18 head lamp (LO: LH) connector terminal No.1 to earth connector terminal No.5 (HI and LO:RH), No.2 (HI and LO:LH).





  • Check the earth wires for open circuit.

Q. Is the check result normal?

Go to Step 8.

Repair the wiring harness.

Step 6. Connector check: A-14X front-ECU connector.

Q. Is the check result normal?

Go to Step 7.

Repair the defective connector.

Step 7. Check the wiring harness from A-35 head lamp (HI: RH) connector terminal No.1, A-21 head lamp (HI: LH) connector terminal No.1, A-38 head lamp (LO: RH) connector terminal No.2 or A-18 head lamp (LO: LH) connector terminal No.2 to A-14X front-ECU connector terminal Nos.2 (HI) or 6 (LO).






  • Check the output lines for open circuit.

Q. Is the check result normal?

Go to Step 8.

Repair the wiring harness.

Step 8. Retest the system.
(1)Replace the socket of the defective headlamp.
(2)Check that the headlamps operate normally.

Q. Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
Replace the headlamp assembly.