Active Stability Control System (ASC)

DTC U0001: Bus-off

CAUTION:

- If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines CAN Bus Line Diagnostics Flow ).
- If diagnostic trouble code U0001 is set in ASC-ECU, always diagnose the CAN bus line. If there is any fault in the CAN bus lines, an incorrect diagnostic trouble code may be set. In this case, the set diagnostic trouble code is not highly reliable.
- Before replacing the ECU, ensure that the communication circuit is normal.
- When the hydraulic unit (integrated with ASC-ECU) is replaced, always carry out the calibration of the steering wheel sensor, the G and yaw rate sensor and brake fluid pressure sensor (Refer to Testing and Inspection , Testing and Inspection and Testing and Inspection ).

DTC SET CONDITIONS

This diagnostic trouble code is set when ASC-ECU has ceased the CAN communication (bus off).

COMMENTS ON TROUBLE SYMPTOM

Malfunction of wiring harness, connector (s), or ASC-ECU may be present.

PROBABLE CAUSES

- Wiring harness or connector failure of CAN bus line
- ASC-ECU malfunction
- Other ECU malfunction

DIAGNOSIS

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

Use scan tool MB991958 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 ASC-ECU) (Refer to Service and Repair), and then go to Step 3.
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.