Inspection Procedure 3

Inspection Procedure 3: The front fog light indicator 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.






TECHNICAL DESCRIPTION (COMMENT)

If the fog light indicator does not illuminate normally, connector(s), wiring harness in the CAN bus lines, the ETACS-ECU or the combination meter may be defective.

TROUBLESHOOTING HINTS

- The ETACS-ECU may be defective
- The combination meter may be defective
- Damaged harness wires and connectors

DIAGNOSIS

STEP 1. Check the fog lights.

When the fog light switch is operated, check that the fog lights illuminate and go off normally.

Q. Is the fog lights normal?

YES Go to Step 2.
NO First, repair the front fog lights. Refer to Inspection Procedure 2 "One of the front fog lights does not illuminate Inspection Procedure 2."
STEP 2. Using scan tool MB991958, diagnose the CAN bus line.

(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 too (M.U.T.-III) Reading and Clearing Diagnostic Trouble Codes."

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

(3)Diagnose the CAN bus line.

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

Q. Is the CAN bus line found to be normal?

YES Go to Step 3.
NO Repair the CAN bus line CAN Bus Diagnostics Chart).
STEP 3. Using scan tool MB991958, read the combination meter diagnostic trouble code.

(1)Check whether a combination meter-related DTC is set.

(2)Turn the ignition switch to the "ON" position.
Check whether the combination meter-related DTC is set.

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

Q. Is the DTC set?

YES Diagnose the combination meter (Refer to combination meter, Diagnosis Combination Meter).
NO Go to Step 4.
STEP 4. Using scan tool MB991958, check actuator test.

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

(2)Perform the actuator test for the combination meter, and check that the fog light indicator illuminates (Refer to combination meter, Diagnosis Symptom Chart).

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

Q. Is the check result normal?

YES Replace the ETACS-ECU.
NO Replace the combination meter.