Inspection Procedure C-13: The rear fog lamp switch signal is not received.












caution Whenever the ECU is replaced, ensure that the input signal circuit is normal.

COMMENTS ON TROUBLE SYMPTOM
Input signal from the rear fog lamp switch is used to operate the rear fog lamps. If the signal is abnormal, the rear fog lamps will not illuminate and extinguish normally.

PROBABLE CAUSES

  • Malfunction of the fog lamp switch
  • Malfunction of the ETACS-ECU
  • Damaged harness wires and connectors

DIAGNOSIS PROCEDURE

STEP 1. Connector check: D-28 fog lamp switch connector

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

STEP 2. Check the rear fog lamp switch.
Refer to .

Q. Is the check result normal?
Go to Step 3.
Replace the fog lamp switch.

STEP 3. Resistance measurement at D-28 fog lamp switch connector.
(1)Remove the fog lamp switch, and measure at the wiring harness side.
(2)Continuity between D-28 fog lamp switch connector terminal No.6 and body earth
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 between D-28 fog lamp switch connector terminal No.6 and body earth.

  • Check the earth wires for open circuit.

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

STEP 5. Connector check: D-421 ETACS-ECU connector

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

STEP 6. Check the wiring harness between D-421 ETACS-ECU connector terminal No.21 and D-28 fog lamp switch connector terminal No.5.

  • Check the input line for open circuit.

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

STEP 7. Retest the system.
Check that the rear fog lamp switch signal is received 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 ETACS-ECU.