Inspection Procedure I-5
Headlight, Tail Light: Headlights do not Illuminate When the Lighting Switch is at "AUTO," "TAIL," and "PASSING" Position, but Illuminate at Low-beam when the Switch is at "HEAD" Position. At this Position, the Headlights cannot be Changed into High Beam by Operating the Dimmer SwitchNOTE: This troubleshooting requires use of scan tool MB991502 and SWS monitor kit MB991862. For details of how to use the SWS monitor, refer to "How to use SWS monitor".
TECHNICAL DESCRIPTION (COMMENT)
If the headlights illuminate at low-beam regardless of the lighting switch positions, the headlight operation is in fail-safe mode.
TROUBLESHOOTING HINTS
- Malfunction of the column switch
- Malfunction of the front-ECU
- Malfunction of the ETACS-ECU
- Damaged harness wires and connectors
Use scan tool to select "ECU CHECK" on the SWS monitor display.
Check the following ECUs:
- ETACS-ECU
- column-ECU
- front-ECU
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. When the ignition switch is turned to the "LOCK" (OFF) position, scan tool MB991502 should show "OK" on the "ECU CHECK" menu.
Q: Are "OK" displayed on the "ETACS ECU", "COLUMN ECU" and "FRONT ECU"?
"OK" are displayed for all the items : Replace the front- ECU. Check that the headlights and the tail lights illuminate normally.
"NG" is displayed on the "ETACS ECU" menu : Refer to Inspection Procedure A-3 "Communication with ETACS-ECU is impossible."
"NG" is displayed on the "COLUMN ECU" menu : Refer to Inspection Procedure A-2 "Communication with column switch (column-ECU) is impossible."
"NG" is displayed on the "FRONT ECU" menu : Refer to Inspection procedure A-4 "Communication with front-ECU is impossible."