Inspection Procedure J-9

Headlight, Tail Light: Headlight Automatic Shutdown Function does not Work Normally.

NOTE: 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."

Headlight Automatic Shut-down Function:

CIRCUIT OPERATION
The ETACS-ECU operates the headlight automatic shutdown function according to the following signals:
- Ignition switch (IG1): OFF
- Driver's door switch: ON
- Tail light switch: ON
- Headlight switch: ON

The ETACS-ECU operates the headlight automatic shutdown function under the following conditions:
- Ignition key: Other than "ON" position
- Driver's door: open
- Tail light or headlight: Illuminating

TECHNICAL DESCRIPTION (COMMENT)
If the function does not work normally, the input circuit system from the switches, the ETACS-ECU or the front-ECU may be defective (refer to "CIRCUIT OPERATION").

TROUBLESHOOTING HINTS
- Malfunction of the driver's door switch
- Malfunction of the column switch (turn-signal light and lighting switch)
- Malfunction of the ETACS-ECU
- 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







Check the input signal by using service data of the SWS monitor.
Check the input signals from the following switches:
- Ignition switch: "ON" to "OFF"
- Lighting switch: "TAIL" or "HEAD"

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 "LIGHTING - HD AUTO-CUT" (FUNCTION DIAG), and check that normal conditions are displayed on the items described in the table.




4. When the driver's door is opened, check that normal conditions are displayed on the items described in the table.

Q: Does the scan tool display the items "TAIL LIGHT SW", "IG SW IG1", "DR DOOR SW" and "H/L AUTO-CUT" as normal condition?

YES: Replace the front-ECU. Check that the headlight automatic shutdown function works normally.

NO:
- The scan tool does not show the respective normal condition for item "TAILLIGHT SW." Refer to Inspection Procedure O-7 "ETACS-ECU does not receive a signal from the tail light switch."
- The scan tool does not show the respective normal condition for item "IG SW(IG1)." Refer to Inspection Procedure O-2 "ETACS-ECU does not receive a signal from the ignition switch (IG1)."
- The scan tool does not show the respective normal condition for item "DR DOOR SW." Refer to Inspection Procedure O-6 "ETACS-ECU does not receive a signal from the driver's or the front passenger's door switch."
- The scan tool does not show the respective normal condition for item "H/L AUTO-CUT." Replace the front-ECU. Check that the headlight automatic shutdown function works normally.