Code No. U0126: Steering Wheel Sensor CAN Time-out


caution If diagnosis code U0126 is set from AS&G-ECU, surely perform CAN bus line diagnosis.
caution Replace ECU after certainly confirming that the communication circuits are normal.

TROUBLE JUDGMENT


Check Conditions
  • 2 seconds later after the ignition switch has been in "ON" position or the engine has started up.
  • The battery voltage is more than 9 V and is less than 16 V.
Judgement Criterion
  • Unable to receive the signals from the steering wheel sensor for 4 seconds.

COMMENTS ON TROUBLE SYMPTOM


Current malfunction
  • The failure is possibly caused by malfunction of the harness and connector in CAN bus line between AS&G-ECU and steering wheel sensor, by malfunction in the power supply system of steering wheel sensor, in steering wheel sensor itself, in AS&G-ECU.
Past malfunction
  • Proceed with troubleshooting focusing on malfunction of the harness and connector in CAN bus line between AS&G-ECU and steering wheel sensor and malfunction in the power supply system of steering wheel sensor. For diagnosis procedure, refer to how to cope with past malfunctions (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Treat Past Trouble).
    note In the case of past malfunctions, M.U.T.-III CAN bus line diagnosis cannot detect a malfunction even if there is a malfunction in CAN bus. Therefore, check CAN bus line as in the case of response to intermittent malfunctions (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions). It is possible to narrow down areas with a high possibility of malfunctions from diagnosis codes set to each ECU that performs CAN communication (Refer to GROUP 54C - Explanation about the M.U.T.-III CAN Bus Diagnostics).
FAIL-SAFE AND BACKUP FUNCTION
  • In the normal operation, the auto stop is prohibited.
  • If the malfunction is detected during the auto stop, the auto start is prohibited.

PROBABLE CAUSES



  • Failed harness and connector
  • Failed steering wheel sensor
  • Failed AS&G-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnosis
Use M.U.T.-III to perform CAN bus line diagnosis.

Q. Is the check result normal?
Go to Step 2.
Repair CAN bus line (Refer to GROUP 54C - Troubleshooting - CAN Bus Diagnosis Chart ). After repairing CAN bus line, go to Step 6.

STEP 2. M.U.T.-III diagnosis code
Confirm the diagnosis code is set from the steering wheel sensor.

Q. Is the diagnosis code set?
Perform troubleshooting of the steering wheel sensor (Refer to GROUP 37 - Troubleshooting - Diagnosis Code Chart).
Go to Step 3.

STEP 3. M.U.T.-III diagnosis code
Check that the other ECU performing CAN communication with steering wheel sensor sets diagnosis code No. U0126 (Refer to GROUP 54C - CAN Communication-related Diagnosis Code (U-code) Table ).

Q. Is the diagnosis code set?
Go to Step 4.
Go to Step 5.

STEP 4. M.U.T.-III diagnosis code

  • Reconfirmation of diagnosis code.
Confirm again the diagnosis code is set from the AS&G-ECU.

  1. Erase the set diagnosis code.
  2. Ignition switch: "LOCK" (OFF) → "ON"
  3. Confirm whether the diagnosis code is set.

Q. Is the diagnosis code set?
After replacing the steering wheel sensor, go to Step 6.
Intermittent malfunction in CAN bus line between AS&G-ECU and steering wheel sensor (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions).

STEP 5. M.U.T.-III diagnosis code

  • Reconfirmation of diagnosis code.
Confirm again the diagnosis code is set from the AS&G-ECU.

  1. Erase the set diagnosis code.
  2. Ignition switch: "LOCK" (OFF) → "ON"
  3. Confirm whether the diagnosis code is set.

Q. Is the diagnosis code set?
After replacing the AS&G-ECU, go to Step 6.
Intermittent malfunction in CAN bus line between AS&G-ECU and steering wheel sensor (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions).

STEP 6. M.U.T.-III diagnosis code

  • Reconfirmation of diagnosis code.
Confirm again the diagnosis code is set from the AS&G-ECU.

  1. Erase the set diagnosis code.
  2. Ignition switch: "LOCK" (OFF) → "ON"
  3. Confirm whether the diagnosis code is set.

Q. Is the diagnosis code set?
Go to Step 1.
Check end.