Inspection Procedure 7

Inspection Procedure 7: The headlight automatic shutdown function does not work normally.

CAUTION:
Whenever the ECU is replaced, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.

OPERATION

The ETACS-ECU operates this function in accordance with the input signals from column switch (lighting switch), ignition switch (IG1), and front door switch (LH).

TECHNICAL DESCRIPTION (COMMENT)

If the headlight automatic shutdown function does not work normally, the above described input circuits or ETACS-ECU may have a problem. Also, it may be possible that the headlight automatic shutdown function is set to "Disable" through configuration function.

TROUBLESHOOTING HINTS

- Malfunction of front door switch (LH)
- Malfunction of the ETACS-ECU
- The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector

DIAGNOSIS

Required Special Tools:

- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)

STEP 1. Using scan tool MB991958, Check the configuration function.

Use the ETACS-ECU configuration function to check that the "Head light auto cut customize" is set to "Enable (C-spec.)."





(1)
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 scan tool MB991958. Refer to "How to connect the scan tool (M.U.T.-III) Reading and Clearing Diagnostic Trouble Codes."
(2)Turn the ignition switch to the "ON" position.
(3)Use the ETACS-ECU configuration function to check that the "Headlight auto cut customize" is set to "Enable (C-spec.)."
(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the check result normal?

YES Go to Step 2.

NO Use the ETACS-ECU configuration function to set the "Headlight auto cut customize" to "Enable (C-spec.)." (Refer to Programming and Relearning).

STEP 2. Using scan tool MB991958, read the diagnostic trouble code.

(1)Turn the ignition switch to the "ON" position.

(2)Check whether the ETACS-ECU related DTC is set.

(3)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the DTC set?

YES Diagnose the ETACS-ECU (Refer to ETACS, Diagnosis Electronic Time and Alarm Control System (ETACS)).
NO Go to Step 3.
STEP 3. Using scan tool MB991958, check data list.

Use the ETACS-ECU service data to check the signals related to the operation of headlight automatic shutdown function.

- Turn the ignition switch to the LOCK (OFF) position.
- Illuminate the headlights.





- Open the driver's door.





Q. Does scan tool MB991958 display the items "Head light LO ON duty", "IG voltage" and "Dr door ajar switch" as normal condition?

YES Go to Step 4.
NO Troubleshoot the ETACS-ECU. Refer to ETACS, Diagnosis Symptom Chart.
STEP 4. Retest the system

Check that the headlight automatic shutdown function works normally.

Q. Is the check result normal?

YES The trouble can be an intermittent malfunction How to Cope With Intermittent Malfunctions).
NO Replace the ETACS-ECU.