Inspection Procedure J-9

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

Headlight Automatic Shutt-down Function:

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." How To Use SWS Monitor

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
- The driver's door switch may be defective
- The column switch (turn-signal light and lighting switch) may be defective
- The ETACS-ECU may be defective
- The front-ECU may be defective
- The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector

DIAGNOSIS

Required Special Tools:
- MB991223: Harness Set
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: Vehicles communication interface (V.C.I.)
- 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 MB991910 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 table.




5. 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 MB991958 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. Verify that the headlight automatic shutdown function works normally.
Normal condition is not displayed for "TAILLIGHT SW": Refer to Inspection Procedure O-7 "ETACS-ECU does not receive any signal from the tail light switch."
Normal condition is not displayed for "IG SW (IG1)": Refer to Inspection Procedure O-2 "ETACS-ECU does not receive any signal from the ignition switch (IG1)."
Normal condition is not displayed for "FRONT DOOR SW": Refer to Inspection Procedure O-6 "ETACS-ECU does not receive any signal from the driver's or the front passenger's door switch."
Normal condition is not displayed for "H/L AUTO-CUT": Replace the front-ECU. Verify that the headlight automatic shutdown function works normally.