Inspection Procedure J-4

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

NOTE: This troubleshooting requires use of scan tool MB991958 and SWS monitor kit MB991862. For details of how to use the SWS monitor, refer to "How to use SWS monitor." How To Use SWS Monitor

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: Harness Set
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: Vehicles communication interface
- MB991827: MUT-III USB cable
- MB991911: MUT-III Main harness B
- MB991813: SWS monitor kit
- MB991806: SWS monitor cartridge
- MB991812: SWS monitor harness (for column-ECU)
- MB991922: Probe harness

STEP 1. Check the headlights.

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

The headlights illuminate normally: Go to Step 2.

Headlights (low-beam) do not illuminate normally: Refer to Inspection Procedure J-2 "Headlights (low-beam) do not illuminate normally."

Headlights (high-beam) do not illuminate normally: Refer to Inspection Procedure J-3 "Headlights (high-beam) do not illuminate normally."

STEP 2. Check the input signal by using "DATA LIST" of the SWS monitor.
Tun the passing switch to the "ON" position before checking input signals from the passing switch.

CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958. Connect special tool MB991911 before connecting special tool MB991812. Be sure to connect special tool MB991806 after turning on special tool MB991824.







1. Connect the special tool. Refer to "How to connect SWS monitor." How to Connect SWS Monitor
2. Operate scan tool MB991958 according to the procedure below to display "COLUMN ECU."
a. Select "Interactive Diagnosis."
b. Select "System select."
c. Select "SWS."
d. Select "SWS MONITOR."
e. Select "Data List."
f. Select "COLUMN ECU."




3. Check that normal conditions are displayed on the items described in the given table.

Q: Does the scan tool display "PASSING SW" as normal condition?

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 O-7 "ETACS-ECU does not receive a signal from the passing light switch."