Inspection Procedure 6: One of the headlamps does not illuminate.


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










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

PROBABLE CAUSES

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

DIAGNOSIS PROCEDURE

STEP 1. Connector check: A-40 headlamp (HI: RH) connector or A-23 headlamp (HI: LH) connector, A-41 headlamp (LO: RH) connector <without discharge headlamp>, A-20 headlamp (LO: LH) connector <without discharge headlamp>, A-39 headlamp (LO: RH) connector <with discharge headlamp> or A-25 headlamp (LO: LH) connector <with discharge headlamp>.

Q. Is the check result normal?
Go to Step 2.
Repair the defective connector.

STEP 2. Check the bulbs of the headlamp.
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-40 headlamp (HI: RH) connector or A-23 headlamp (HI: LH) connector, A-41 headlamp (LO: RH) connector <without discharge headlamp>, A-20 headlamp (LO: LH) connector <without discharge headlamp>, A-39 headlamp (LO: RH) connector <with discharge headlamp> or A-25 headlamp (LO: LH) connector <with discharge headlamp>.
(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-40 headlamp (HI: RH) connector terminal No.1 and body earth
  • Resistance between A-23 headlamp (HI: LH) connector terminal No.1 and body earth
  • Resistance between A-41 headlamp (LO: RH) connector terminal No.1 and body earth <without discharge headlamp>
  • Resistance between A-20 headlamp (LO: LH) connector terminal No.1 and body earth <without discharge headlamp>
  • Resistance between A-39 headlamp (LO: RH) connector terminal No.1 and body earth <with discharge headlamp>
  • Resistance between A-25 headlamp (LO: LH) connector terminal No.1 and body earth <with discharge headlamp>
OK: Continuity exists (2 Ω or less)

Q. Is the check result normal?
Go to Step 5.
Go to Step 4.

STEP 4. Check the wiring harness from A-40 headlamp (HI: RH) connector terminal No.1 or A-23 headlamp (HI: LH) connector terminal No.1, A-41 headlamp (LO: RH) connector terminal No.1 <without discharge headlamp> or A-20 headlamp (LO: LH) connector terminal No.1 <without discharge headlamp>, A-39 headlamp (LO: RH) connector terminal No.1 <with discharge headlamp> or A-25 headlamp (LO: LH) connector terminal No.1 <with discharge headlamp>to body earth.

  • Check the earth wires for open circuit.

Q. Is the check result normal?
Go to Step 7.
Repair the wiring harness.

STEP 5. Connector check: A-08X front-ECU connector.

Q. Is the check result normal?
Go to Step 6.
Repair the defective connector.

STEP 6. Check the wiring harness from A-40 headlamp (HI: RH) connector terminal No.2, A-23 headlamp (HI: LH) connector terminal No.2, A-41 headlamp (LO: RH) connector terminal No.2 <without discharge headlamp> or A-20 headlamp (LO: LH) connector terminal No.2 <without discharge headlamp>, A-39 headlamp (LO: RH) connector terminal No.2 <with discharge headlamp> or A-25 headlamp (LO: LH) connector terminal No.2 <with discharge headlamp> to A-08X 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 7.
Repair the wiring harness.

STEP 7. 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.