Inspection Procedure 1

Inspection Procedure 1: The front dome light does not illuminate normally.

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














TROUBLE JUDGMENT

The ETACS-ECU illuminates and extinguishes the front dome light in accordance with the input signals below.

- Ignition switch (IG1)
- Key reminder switch
- Door switches
- Front door lock actuator

TECHNICAL DESCRIPTION (COMMENT)

If this does not work normally, the above switch input circuit(s), front dome light, or ETACS-ECU may have a problem.

TROUBLESHOOTING HINTS

- Malfunction of the key reminder switch
- Malfunction of door switch
- Malfunction of the front door lock actuator switch
- Malfunction of front dome light
- 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. Rear dome light operation check.

Check that the rear dome light illuminates and extinguishes normally.

Q. Does rear dome light work normally?

YES Go to Step 2.
NO Replace the ETACS-ECU.
STEP 2. Using scan tool MB991958, read the diagnostic trouble code.





(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 whether the ETACS-ECU related DTC is set.
(4)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.
- Remove the ignition key from the ignition key cylinder.
- Open each door.





Q. Does scan tool MB991958 display the items "Dr door unlock", "IG voltage", "Dr door ajar switch", "As door ajar switch", "RR door ajar switch", "RL door ajar switch" and "Handle lock switch" as normal condition?

YES : (Normal conditions are displayed for all items.) Go to Step 4.
NO : (Normal condition is not displayed.) Troubleshoot the ETACS-ECU. Refer to ETACS, Diagnosis, Input signal chart Symptom Chart.
STEP 4. Check front dome light connector D-03 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is front dome light connector D-03 in good condition?

YES Go to Step 5.
NO Repair or replace the damaged component(s). Harness Connector Inspection.
STEP 5. Front dome light bulb check

Check that the front dome light bulb is normal.

Q. Is front dome light bulb normal?

YES Go to Step 6.
NO Replace the front dome light bulb.
STEP 6. Check ETACS-ECU connector C-316 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is ETACS-ECU connectors C-316 in good condition?

YES Go to Step 7.
NO Repair or replace the damaged component(s). Harness Connector Inspection.
STEP 7. Check the wiring harness between front dome light connector D-03 (terminal 2, 3) and ETACS-ECU connector C-316 (terminal 6, 5)

- Check the line for open circuit.

Q. Are wiring harness between front dome light connector D-03 (terminal 2, 3) and ETACS-ECU connector C-316 (terminal 6, 5) in good condition?

YES Go to Step 8.
NO The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary.
STEP 8. Check the wiring harness between front dome light connector D-03 (terminal 1) and body ground.

- Check the ground wires for open circuit.

Q. Is wiring harness between front dome light connector D-03 (terminal 1) and body ground in good condition?

YES Replace the front dome light, and then go to Step 9.
NO The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary.
STEP 9. Retest the system

Check that the front dome light illuminates and extinguishes normally.

Q. Do the front dome light work normal?

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