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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 (Refer to GROUP 54C - Diagnostic trouble code diagnosis ).
  • If DTC U0001 is set in ASC-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.
  • 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 , and ).

DTC SET CONDITIONS
This DTC 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
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. M.U.T.-III CAN bus diagnosis
Use scan tool to diagnose the CAN bus lines.

Q. Is the check result normal?
Go to Step 2.
Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostic table ). On completion, go to Step 3.

STEP 2. Check whether the DTC is reset.

Q. Is DTC U0001 set?
Replace the hydraulic unit (ASC-ECU) (Refer to ), and then go to Step 3.
If the trouble symptom is resolved, an intermittent malfunction such as poorly engaged connector(s) or wiring harness is suspected (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).

STEP 3. Check whether the DTC is reset.

Q. Is DTC U0001 set?
Return to Step 1.
The procedure is complete.