Inspection Procedure J-4

Headlight and Taillight: When the passing switch is turned "ON", the headlights (low-beam or high-beam) do not illuminate.

NOTE: This troubleshooting procedure requires the use of scan tool MB991958 and SWS monitor kit MB991813. For details on how to use the SWS monitor, refer to "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
- Trouble in input signal system
- The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector
- The front-ECU may be defective

DIAGNOSIS

Required Special Tools:
- MB991223: Harness Set
- MB992006: Extra Fine Probe
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: M.U.T.-III USB Cable
- MB991911: M.U.T.-III Main Harness B
- MB991813: SWS monitor kit
- MB991806: SWS monitor cartridge
- MB991812: SWS monitor harness (for column-ECU)
- MB991922: Probe harness

STEP 1. Verify the headlights.

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

YES : Go to Step 2.

NO : Refer to Inspection Procedure J-2 "Headlights (low-beam) do not illuminate normally."

NO : Refer to Inspection Procedure J-3 "Headlights (high-beam) do not illuminate normally."

STEP 2. Check the input signal by using "DATA LIST" menu 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 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."
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 table.

Q: Does the scan tool MB991958 display the items "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 N-6 "The ETACS-ECU does not receive any signal from the passing light switch."