Inspection Procedure I-4

Headlight, Tail Light: When the Passing Switch is Turned "ON", the Headlights (Low-beam or High-beam) do not Illuminate

TECHNICAL DESCRIPTION (COMMENT)
If both of the headlights (low-beam and high-beam) do not illuminate, the input circuit from the passing switch or the front-ECU may be defective.

TROUBLESHOOTING HINTS
- Malfunction of the column switch
- Malfunction of the front-ECU
- Damaged harness wires or connectors

DIAGNOSIS

Required Special Tools:
- MB991223: Test Harness Set
- MB991502: Scan Tool (MUT-II)
- MB991862: SWS monitor kit

STEP 1. Check the headlights.

Q: Do the headlights (low-beam and high-beam) illuminate normally?

YES: Go to Step 2.
Headlights (low-beam) do not illuminate normally : Refer to Inspection Procedure K-2 "Headlights (low-beam) do not illuminate normally."
Headlights (high-beam) do not illuminate normally : Refer to Inspection Procedure K-3 "Headlights (high-beam) do not illuminate normally."

STEP 2. Check the input signal by using service data of the SWS monitor.
Turn the passing switch to the "ON" position before checking input signals from the passing switch.

CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502. Also connect SWS monitor kit MB991862 after turning on scan tool MB991502.







1. Connect scan tool MB991502 to the data link connector.
2. Connect SWS monitor kit MB991862 to the column switch connector.




3. Select "COLUMN ECU" (DATALIST), and check that normal conditions are displayed on the items described in the table.

Q: Is normal condition displayed on the "PASSING SW"?

YES: Replace the front-ECU. When the passing switch is turned "ON", the headlights (low-beam and high-beam) should illuminate normally.

NO: Refer to Inspection Procedure L-5 "ETACS-ECU does not receive a signal from the passing switch."