Inspection Procedure 15

Inspection Procedure 15: The coming home light 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.

TECHNICAL DESCRIPTION (COMMENT)

When the coming home light function does not operate normally, the keyless entry system or the ETACS-ECU may have a problem. Or, the coming home light function may have been set to disabled using the customization function.

TROUBLESHOOTING HINTS

- Malfunction of the keyless entry system
- Malfunction of the ETACS-ECU

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.





(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 scan tool (M.U.T.-III) Reading and Clearing Diagnostic Trouble Codes."
(2)Turn the ignition switch to the "ON" position.
(3)Check that any one of the followings other than "Disabled" is set for "Coming home light" with a customization function.

- 15 sec
- 30 sec
- 60 sec
- 180 sec
(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is it set to other than "Disabled"?

YES Go to Step 2.

NO Set "Coming home light" to any one other than "Disabled" with a customization function (Refer to Programming and Relearning).

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

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

(2)Check whether the ETACS-ECU 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 data list to check the signals related to the front dome light.

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





OK: Normal condition is displayed.


Q. Is the check result normal?

YES Go to Step 4.
NO Troubleshoot the ETACS-ECU. Refer to Inspection Procedure 2 "The ignition switch (IG1) signal is not received" Inspection Procedure 2.
STEP 4. Check the headlights.

When the lighting switch is operated, check that the headlights illuminate/go off normally.

Q. Is the check result normal?

YES Go to Step 5.
NO Troubleshoot the headlights. Refer to trouble symptom chart Symptom Chart.
STEP 5. Retest the system.

Check that the coming home light 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.