Inspection Procedure 7

Inspection Procedure 7: ABS system inoperative.

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.

COMMENTS ON TROUBLE SYMPTOM

In case of this trouble symptom, ABS system operation may be disabled. DTC may be set by the ABS system using scan tool.

PROBABLE CAUSES

- Low battery voltage

- Wiring harness or connector failure of CAN bus line

- The ABS-ECU is defective.

- Different ETACS-ECU, abnormal variant coding information

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).
On completion, go to Step 2.
STEP 2. DTC check after resetting CAN bus lines

Q. Is any DTC set?

YES Carry out the relevant troubleshooting (Refer to Anti-Lock Braking System (ABS)).
NO Go to Step 3.
STEP 3. Hydraulic unit (integrated with ABS-ECU) check

Refer to Anti-Lock Braking System (ABS).

Q. Is the check result normal?

YES Go to Step 4.
NO Repair the brake pipe or replace the hydraulic unit (integrated with ABS-ECU)
(Refer to Anti-Lock Braking System (ABS)).
STEP 4. Operation check

Q. Does ABS operate normally?

YES The procedure is complete.
NO Check the brake system related components except the ABS system.