Inspection Procedure
1: The front fog lamps do not illuminate normally.
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Whenever the ECU is replaced,
ensure that the power supply circuit, the earth circuit and the communication circuit are normal.
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CIRCUIT OPERATION
If the front 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 front 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
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(1)Operate the M.U.T.-III to read the ETACS-ECU option coding information.
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(2)Check that the "Front fog lamp" is set to "Present."
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Q.
Is the check result normal?
Go to Step 2.
Operate the M.U.T.-III to set the option coding "Front 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 in 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 front fog
lamp function.
- Turn the fog lamp switch to ON.
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Item No.
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Item name
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Normal condition
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70
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Front fog lamp
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ON
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OK: Normal condition is displayed.
Q.
Is the check result normal?
Go to Step 5.
Troubleshoot the ETACS-ECU. Refer to Inspection Procedure 9 "The column switch signal
is not received" .
STEP 5. Check the front fog lamp relay
Refer to .
Q.
Is the check result normal?
Go to Step 6.
Replace the front fog lamp relay.
STEP 6. Voltage measurement at the front fog lamp relay connector
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(1)Remove the front fog lamp relay, and measure at the relay box side.
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(2)Measure the voltage between the front fog lamp relay connector (power supply terminal)
and the body earth.
OK: System voltage
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Q.
Is the check result normal?
Go to Step 8.
Go to Step 7.
STEP 7. Check of short to power supply, and open circuit in power
supply lines between front fog lamp relay connector and the fusible link.
Q.
Is the check result normal?
Go to Step 11.
Repair the connector(s) or wiring harness.
STEP 8. Check of short to power supply, and open circuit in FOGY line
between front fog lamp relay connector and the ETACS-ECU connector.
Q.
Is the check result normal?
Go to Step 9.
Repair the connector(s) or wiring harness.
STEP 9. Check of short to power supply, and open circuit in output
lines between front fog lamp relay connector and the front fog lamp (LH) or front fog lamp (RH)
connector.
Q.
Is the check result normal?
Go to Step 10.
Repair the connector(s) or wiring harness.
STEP 10. Check of open circuit in body earth lines between the front
fog lamp (LH) or front fog lamp (RH) connector and body earth.
Q.
Is the check result normal?
Go to Step 11.
Repair the connector(s) or wiring harness.
STEP 11. Retest the system
Check that the front fog lamps 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 ).
Replace the ETACS-ECU (Refer to ).