If there is any problem in the CAN bus lines, an incorrect diagnosis code may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C - Troubleshooting ).
Whenever ECU is replaced, ensure that the CAN bus lines are normal.
When the steering wheel sensor is replaced, always carry out calibration to make ASTC-ECU learn the neutral point (Refer to ).
When the hydraulic unit assembly (integrated with ASTC-ECU) is replaced, always carry out the calibration of the steering wheel sensor and the G sensor (Refer to ).
OPERATION
The steering wheel sensor outputs the steering wheel status to ASTC-ECU via the CAN bus lines.
DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set when ASTC-ECU has detected the communication error in the steering wheel sensor.
PROBABLE CAUSES
Current trouble
Malfunction of the column switch assembly (Integrated with steering wheel sensor)
Malfunction of the hydraulic unit assembly (integrated with ASTC-ECU)
Noise interference
Past trouble
Carry out diagnosis with particular emphasis on wiring harness and connector failures between ASTC-ECU and the steering wheel sensor. For diagnosis procedures, refer to How to treat past trouble (GROUP 00 - How to Cope with Intermittent Malfunctions ).
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 3.
Repair the CAN bus lines (Refer to GROUP 54C - Troubleshooting ). On completion, go to Step 2.
STEP 2. Diagnosis code recheck after resetting CAN bus lines
Q.
Is diagnosis code No. U0428 set?
Go to Step 3.
This diagnosis is complete.
STEP 3. Check for diagnosis codes of other systems.
Check if diagnosis code(s) other than U0428 is set.
Q.
Is the diagnosis code set?
Follow the relevant diagnosis code procedure, and then go to Step 5.
Go to Step 4.
STEP 4. Diagnosis code recheck
Check again if the diagnosis code is set.
(1)Erase the set diagnosis code.
(2)Ignition switch: "LOCK" (OFF)
(3)Ignition switch: "ON"
Q.
Is diagnosis code No. U0428 set?
Replace the column switch assembly (Integrated with steering wheel sensor) (Refer to GROUP 54A - Column Switch ). Then go to Step 5.
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
STEP 5. Diagnosis code recheck
Check again if the diagnosis code is set.
(1)Erase the set diagnosis code.
(2)Ignition switch: "LOCK" (OFF)
(3)Ignition switch: "ON"
Q.
Is diagnosis code No. U0428 set?
Replace the hydraulic unit assembly (integrated with ASTC-ECU) (Refer to ).
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).