U1003

DTC U1003: G and yaw rate sensor bus-off





CAUTION:
^ 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.
^ Whenever ECU is replaced, ensure that the CAN bus lines are normal.
^ Do not drop or shock the G and yaw rate sensor.
^ When the G and yaw rate sensor is replaced, always carry out calibration to make ASC-ECU learn the neutral point.
^ 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.

CIRCUIT OPERATION
The G and yaw rate sensor outputs the signal to ASC-ECU via the special CAN bus lines.

DTC SET CONDITIONS
This diagnostic trouble code is set when ASC-ECU cannot receive the signal sent from the G and yaw rate sensor.

PROBABLE CAUSES
^ Wring harness or connector failure for the special CAN bus lines between ASC-ECU and the G and yaw rate sensor
^ G and yaw rate sensor malfunction
^ ASC-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

STEP 1. M.U.T.-III CAN bus diagnostics
Use scan tool to diagnose the CAN bus lines.
Q: Is the check result normal?
YES: Go to Step 3.
NO: Repair the CAN bus lines. On completion, go to Step 2.

STEP 2. Diagnostic trouble code recheck after resetting CAN bus lines
Q: Is DTC U1003 set?
YES: Go to Step 3.
NO: The procedure is complete.

STEP 3. Connector check: A-02 ASC-ECU connector, C-26 G and yaw rate sensor connector
Q: Is the check result normal?
YES: Go to Step 4.
NO: Repair the connector, and then go to Step 7.

STEP 4. Wiring harness check between A-02 ASC-ECU connector terminals No.29 and C-26 G and yaw rate sensor connector terminals No.2, and between A-02 ASC-ECU connector terminals No.25 and C-26 G and yaw rate sensor connector terminals No.3.
Check for open or short circuit in communication circuit
Q: Is the check result normal?
YES: Go to Step 5.
NO: Repair the wiring harness, and then go to Step 7.

STEP 5. Check whether the diagnostic trouble code is reset.
Q: Is DTC U1003 set?
YES: Replace the G and yaw rate sensor and then go to Step 6.
NO: The procedure is complete.

STEP 6. Check whether the diagnostic trouble code is reset.
Q: Is DTC U1003 set?
YES: Replace the ASC-ECU, and then go to Step 7.
NO: The procedure is complete.

STEP 7. Check whether the diagnostic trouble code is reset.
Q: Is DTC U1003 set?
YES: Return to Step 1.
NO: This diagnosis is complete.