If the EPS-ECU
sets the 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.
Before replacing ECU, ensure that the communication circuit is normal.
TROUBLE JUDGEMENT
The diagnosis code is stored when a EPS-ECU bus-off occurs.
COMMENT ON TROUBLE SYMPTOM
The wiring harness, connector, or EPS-ECU may be faulty.
PROBABLE CAUSES
Defective wire(s) or connector(s) in the CAN bus lines
Malfunction of the EPS-ECU
DIAGNOSIS PROCEDURE
STEP 1. M.U.T.-III CAN bus diagnosis
Use the M.U.T.-III 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, Troubleshooting .)
STEP 2. Diagnosis code recheck
Recheck if the diagnosis code is set.
(1)Turn the electric motor switch to the "LOCK" (OFF) → "ON" position.
(2)Start the electric motor unit.
(3)Check if the diagnosis code No. U1073 is set as a current trouble.
Q.
Is the diagnosis code No. U1073 set?
Replace EPS-ECU.
Intermittent malfunction. (Refer to GROUP 00 - How to Cope with Intermittent
Malfunction .)
Go to Step 2.
Repair the CAN bus lines. (Refer to GROUP 54C, Troubleshooting 
.)