Inspection Procedure 3

Inspection Procedure 3: ABS warning light does not illuminate when ignition switch is turned to the ON position (engine stopped).

CAUTION:

- If there is any problem in the CAN bus lines, an incorrect DTC may be set. Prior to this diagnosis, diagnose the CAN bus lines CAN Bus Diagnostics Chart).

- Whenever ECU is replaced, ensure that the CAN bus lines are normal.

SYSTEM OPERATION

- ABS-ECU sends the illumination request signal of the ABS warning light to the combination meter through ETACS-ECU via CAN communication.

- ABS-ECU illuminates the ABS warning light via ETACS-ECU for approximately 3 seconds for valve check with the ignition switch turned to the ON position.

COMMENTS ON TROUBLE SYMPTOM

This may be caused by faults in the CAN bus line, ETACS-ECU, combination meter or ABS-ECU.

PROBABLE CAUSES

- Damaged wiring harness and connectors

- Malfunction of ETACS-ECU

- Combination meter malfunction

- ABS-ECU malfunction

- Malfunction of coding data for 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

STEP 1. Using scan tool MB991958, diagnose the CAN bus line.

Use scan tool to diagnose the CAN bus lines.

Q. Is the check result normal?

YES Go to Step 2.
NO Repair the CAN bus lines CAN Bus Diagnostics Chart).
Then go to Step 9.
STEP 2. Using scan tool MB991958, check the DTC

Use scan tool to check the DTC for the ABS system.

Q. Is the DTC set?

YES Carry out the diagnosis for the DTC. (Refer to Anti-Lock Braking System (ABS).)
NO Go to Step 3.
STEP 3. Using scan tool MB991958, check the actuator test

Perform the following actuator test by the combination meter system, and check if the ABS warning light illuminates Actuator Test Reference Table).

- Item No.07: Indicator 1

Q. Is the check result normal?

YES Go to Step 4.
NO Troubleshoot the combination meter Symptom Chart). Then go to Step 9
.
STEP 4. Check coding data

Use scan tool to check if coding data stored in ETACS-ECU is normal Coding List).

Q. Is the check result normal?

YES Go to Step 6.
NO Go to Step 5.
STEP 5. ETACS-ECU variant coding

Perform the variant coding to the ETACS-ECU.

Q. Does variant coding succeed?

YES Go to Step 9.
NO Replace the ETACS-ECU Electronic Time and Alarm Control System (ETACS)-ECU Removal and Installation), and then go to Step 9.
STEP 6. Scan tool other system DTC

Using scan tool, check that the DTC U0141 is not set by the combination meter system.

Q. Is the DTC set?

YES Troubleshoot the combination meter Combination Meter), and then go to Step 9
.
NO Go to Step 7.
STEP 7. Scan tool other system DTC

Using scan tool, check that the DTC U0121 is not set by the ETACS system.

Q. Is the DTC set?

YES Troubleshoot the ETACS-ECU Electronic Time and Alarm Control System (ETACS)), and then go to Step 9.
NO Go to Step 8.
STEP 8. Retest the system.

Q. Does the ABS warning light turn ON and OFF normally?

YES Intermittent malfunction How to Cope With Intermittent Malfunctions).
NO Replace the hydraulic unit (integrated with ABS-ECU) (Refer to Anti-Lock Braking System (ABS)).
Then go to Step 9.
STEP 9. Retest the system.

Q. Does the ABS warning light turn ON and OFF normally?

YES The procedure is complete.
NO Return to Step 1.