Inspection Procedure J-9

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

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

Headlight Automatic Shutt-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: 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

Check the input signal by using "FUNCTION DIAG." menu of the SWS monitor.
Check the input signals from the following switches:
- Ignition switch: "ON" to "OFF"
- Lighting switch: "TAIL" or "HEAD"
- Driver's and front passenger's door: closed

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. Turn the ignition switch to the "LOCK" (OFF) position.
3. Operate scan tool MB991958 according to the procedure below to display "H/L AUTO-CUT."
a. Select "Interactive Diagnosis."
b. Select "System select."
c. Select "SWS."
d. Select "SWS MONITOR."
e. Select "Function Diag."
f. Select "LIGHTING."
g. Select "H/L AUTO-CUT."




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




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

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

Normal conditions are displayed for all the items: Replace the front-ECU. Check that the headlight automatic shutdown function works normally.

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 "FRONT 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.