Controller Area Network (CAN)

DTC U1003: G and yaw rate sensor bus-off





CAUTION
^ If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines.
^ Whenever the ECU is replaced, ensure that the CAN bus lines are normal.
^ Do not drop the G and yaw rate sensor or subject it to a shock.
^ When the G and yaw rate sensor is replaced, always perform the calibration to make ASC-ECU learn the neutral point
^ When the hydraulic unit (integrated with ASC-ECU) is replaced, after turning the ignition switch ON and OFF (vehicle information from ETACS-ECU is registered), always perform the calibration of steering wheel sensor, G and yaw rate sensor, brake fluid pressure sensor, cut valve, and inlet valve

CIRCUIT OPERATION
The G and yaw rate sensor outputs the signal to ASC-ECU and S-AWC-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 in special CAN bus lines between ASC-ECU and 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. Using scan tool MB991958, diagnose the CAN bus lines.
Using scan tool MB991958, diagnose the CAN bus lines.

Q: Is the check result normal?
YES: Go to Step 3.
NO: Repair the CAN bus lines. After repairing the CAN bus line, go to Step 2.

STEP 2. DTC recheck after repairing the CAN bus line

Q: Is DTC U1003 set?
YES: Go to Step 3.
NO: The procedure is complete.

STEP 3. Connector check: A-05 ASC-ECU connector, C-46 S-AWC-ECU connector, C-47 intermediate connector, C-50 joint 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-05 ASC-ECU connector terminal No. 18 and C-38 G and yaw rate sensor connector terminal No. 2, between A-05 ASC-ECU connector terminal No. 19 and C-38 G and yaw rate sensor connector terminal No. 3, between C-46 S-AWC-ECU connector terminal No. 9 and C-38 G and yaw rate sensor connector terminal No. 2, between C-46 S-AWC-ECU connector terminal No. 10 and C-38 G and yaw rate sensor connector terminal No. 3
^ Open or short circuit check of 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 DTC is reset.

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

STEP 6. Check whether the DTC is reset.

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

STEP 7. Check whether the DTC is reset.

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