Inspection Procedure M-1: The fog lamps do not illuminate normally.


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


Comments on trouble symptom
If the fog lights do not illuminate normally, the input signal circuit(s) below or the ETACS-ECU may be defective.

  • Tail lamp switch
  • Headlamp switch
  • Automatic lighting switch
  • Fog lamp switch

POSSIBLE CAUSES

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

DIAGNOSTIC PROCEDURE

Step 1. Check that the tail/stop lamps and headlamps operate.
Check that the tail/stop lamps and headlamps illuminate normally.

Q. Is the check result normal?
Go to Step 2.
Check the tail/stop lamps and the headlamps (Refer to trouble symptom chart ).

Step 2. Pulse check
Check the input signals below, which are related to the fog lamps.
System switch
 Check condition
Ignition switch (IG1)
 When turned from ACC to ON
Tail lamp switch
 When the lighting switch is turned to the TAIL position
Headlamp switch
 When the lighting switch is turned to the HEADLAMP position
Fog lamp switch
 When the fog lamp switch is turned from off to on
OK: The M.U.T.-III sounds or the voltmeter needle fluctuates.

Q. Is the check result normal?
All the signals are received normally. : Go to Step 3.
The ignition switch (IG1) signal is not received. : Refer to Inspection Procedure P-2 "The ignition switch (IG1) signal is not received ."
The tail lamp switch signal is not received. : Refer to Inspection Procedure P-5 "The column switch (lighting and turn-signal lamp switch) signal is not received ."
The headlamp switch signal is not received. : Refer to Inspection Procedure P-5 "The column switch (lighting and turn-signal lamp switch) signal is not received ."
The fog lamp switch signal is not received. : Refer to Inspection Procedure P-3 "The fog lamp switch signal is not received ."

Step 3. Connector check: A-08X fog lamp relay connector

Q. Is the check result normal?

Go to Step 4.

Repair the defective connector.

Step 4. Check the fog lamp relay.
Refer to GROUP 54A - Fog lamp .

Q. Is the check result normal?
Go to Step 5.
Replace the fog lamp relay.

Step 5. Voltage measurement at the A-08X fog lamp relay connector.

(1)Remove the fog lamp relay, and measure at the relay box side.

(2)Check the voltage between the fog lamp relay connector and body earth.

  • Voltage between A-08X fog lamp relay connector terminal No.1 and body earth
  • Voltage between A-08X fog lamp relay connector terminal No.2 and body earth
OK: System voltage

Q. Is the check result normal?

Go to Step 7.

Go to Step 6.

Step 6. Check the wiring harness between A-08X fog lamp relay connector terminals No.1 and No.2 to the fusible link (26).


  • Check the power supply line 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 7. Connector check: A-14X front-ECU connector

Q. Is the check result normal?

Go to Step 8.

Repair the defective connector.

Step 8. Check the wiring harness between A-08X fog lamp relay connector terminal No.3 to A-14X front-ECU connector terminal No.1.


  • Check the output lines for open circuit.

Q. Is the check result normal?

Go to Step 9.

Repair the wiring harness.

Step 9. Retest the system.
Check that the fog lamps illuminate 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.