Anti-Lock Braking System (ABS)

DTC U0001: Bus-off

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).

- If DTC U0001 is set in ABS-ECU, always diagnose the CAN bus line. If there is any fault in the CAN bus lines, an incorrect DTC may be set. In this case, the set DTC is not highly reliable.

- Before replacing the ECU, ensure that the communication circuit is normal.

DTC SET CONDITIONS

This DTC is set when ABS-ECU has ceased the CAN communication (bus off).

PROBABLE CAUSES

- Wiring harness or connector failure of CAN bus line

- ABS-ECU malfunction

- Other ECU malfunction

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 3.
STEP 2. Check whether the DTC is reset.

Erase the DTC.

Q. Is DTC U0001 set?

YES Replace the hydraulic unit (integrated with ABS-ECU) (Refer to Anti-Lock Braking System (ABS)).
NO If the trouble symptom is resolved, an intermittent malfunction such as poorly engaged connector(s) or wiring harness is suspected How to Cope With Intermittent Malfunctions).
STEP 3. Check whether the DTC is reset.

Erase the DTC.

Q. Is DTC U0001 set?

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