Code No.U1073 Bus off


caution
  • If the electric power steering-ECU sets diagnosis code No.U1073, diagnose the CAN bus lines. If there is any fault in the CAN bus lines, an incorrect diagnosis code may be set.
  • Whenever the ECU is replaced, ensure that the communication circuit is normal.


TROUBLE JUDGMENT
When the electric power steering-ECU is bus off, it is memorised.

COMMENTS ON TROUBLE SYMPTOM
Harness wire(s), connector(s) or the electric power steering-ECU may be defective.

PROBABLE CAUSES

  • Defective wire(s) or connector(s) in the CAN bus lines
  • Malfunction of the electric power steering-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics

caution Before connecting or disconnecting the M.U.T.-III, turn the ignition switch to the "LOCK" (OFF) position.
(1)Connect M.U.T.-III to the 16-pin diagnosis connector.
(2)Turn the ignition switch to the "ON" position.
(3)Diagnose the CAN bus line.
(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the check result normal?

The malfunction is intermittent. Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction .

Repair the CAN bus line (Refer to GROUP 54C - CAN bus line Diagnostic flow ).