Inspection Procedure
4: The rear fog lamp do not illuminate normally.
caution
Before replacing
the ECU, ensure that the power supply circuit, the earth circuit and the communication circuit
are normal.
When the ETACS-ECU of vehicles without KOS is replaced, the encrypted code of the ignition
key needs to be registered to the ETACS-ECU. (If the encrypted code is not registered, the engine
cannot be started. Register the encrypted code as described in Immobilizer System - How
to Register Key ID .)
CIRCUIT OPERATION
If the rear fog lamps do not illuminate normally, the input signal circuit(s) below or
the ETACS-ECU may be defective.
Tail lamp switch
Headlamp switch
Fog lamp switch
Option coding information
COMMENTS ON TROUBLE SYMPTOM
When the rear fog lamps do not illuminate normally, the mentioned input signal circuit(s)
or ETACS-ECU may be defective.
PROBABLE CAUSES
Malfunction of column switch
Malfunction of the ETACS-ECU
Damaged harness wires and connectors
DIAGNOSIS PROCEDURE
STEP 1. ETACS-ECU coding data check
(1)Operate the M.U.T.-III to read the ETACS-ECU option coding information (Refer to
GROUP 00 - Coding List ).
(2)Check that the "Rear fog lamp" is set to "Present."
Q.
Is the check result normal?
Go to Step 2.
Operate the M.U.T.-III to set the option coding "Rear fog lamp" to "Present,"
and check the trouble symptom.
STEP 2. Check the operation of the position lamps and the headlamps.
Check that the position lamps and the headlamps illuminate normally.
Q.
Is the check result normal?
Go to Step 3.
Check the position lamps and the headlamps (Refer to trouble symptom chart ).
STEP 3. M.U.T.-III diagnosis code
Check if diagnosis code is set to the ETACS-ECU.
Q.
Is the diagnosis code set?
Troubleshoot the ETACS-ECU. Refer to .
Go to Step 4.
STEP 4. M.U.T.-III data list
Use the ETACS-ECU service data to check the signal related to the operation of rear fog
lamp function.
Turn the fog lamp switch to ON.
Item No.
Item name
Normal condition
Item 345
Fog lamp ON
ON
OK: Normal condition is displayed.
Q.
Is the check result normal?
Go to Step 5.
Troubleshoot the ETACS-ECU. Refer to Inspection Procedure 11 "The column switch
signal is not received" .
STEP 5. Check the bulb of the rear fog lamp
Check the bulb of the defective lamp.
Q.
Is the check result normal?
Go to Step 6.
Replace the bulb of the defective lamp.
STEP 6. Resistance measurement at the rear fog lamp connector (earth
terminal).
(1)Disconnect the connector, and measure at the wiring harness side.
(2)Measure the resistance between the rear fog lamp connector (earth terminal) and
body earth. OK: Continuity exists (2 Ω or less)
Q.
Is the check result normal?
Go to Step 8.
Go to Step 7.
STEP 7. Check of open circuit in earth line between the rear fog lamp
connector and body earth.
Q.
Is the check result normal?
Go to Step 8.
Repair the connector(s) or wiring harness.
STEP 8. Check of open circuit in RFOG line between the rear fog lamp
connector and ETACS-ECU connector.
Q.
Is the check result normal?
Go to Step 9.
Repair the connector(s) or wiring harness.
STEP 9. Retest the system
Check that the rear fog lamp illuminate normally.
Q.
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How
to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction ).
).
Go to Step 2.
Operate the M.U.T.-III to set the option coding "Rear fog lamp" to "Present,"
and check the trouble symptom.