U1003

DTC U1003 G and yaw rate sensor bus-off





CAUTION
^ If there is any problem in the CAN bus lines, an incorrect DTC 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.

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

DTC SET CONDITIONS
This DTC is set when the communication error occurs in the exclusive CAN bus communication between the ASC-ECU and the G and yaw rate sensor.

PROBABLE CAUSES
^ Wiring harness or connector failure for the special CAN bus lines between ASC-ECU and the G and yaw rate sensor
^ Malfunction of the G and yaw rate sensor
^ 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 A

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. DTC 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-51 ASC-ECU connector, C-137 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-51 ASC-ECU connector terminal No.18 and C-137 G and yaw rate sensor connector terminal No.2 as well as between A-51 ASC-ECU connector terminal No.19 and C-137 G and yaw rate sensor connector terminal No.3
^ Check the communication circuit for open and short 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. DTC recheck

Q: Is DTC U1003 set?
YES: Replace the G and yaw rate sensor. Then go to Step 6.
NO: Intermittent malfunction.

STEP 6. DTC recheck

Q: Is DTC U1003 set?
YES: Replace the hydraulic unit (ASC-ECU). Then go to Step 7.
NO: The procedure is complete.

STEP 7. DTC recheck

Q: Is DTC U1003 set?
YES: Return to Step 1.
NO: The procedure is complete.