[Previous] [Next]

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 (Refer to .)
  • 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 (Refer to , , , and .)

CIRCUIT OPERATION
The G and yaw rate sensor outputs the signal to ASC-ECU and AWC-ECU via the local 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

  • Wiring 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
  • Connector disconnected or improperly connected
  • Stretched or broken wires

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. Using scan tool MB991958, diagnose the CAN bus lines.
Using scan tool MB991958, 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 .) 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?
Go to Step 3.
The procedure is complete.

STEP 3. Connector check: A-05 ASC-ECU connector, C-46 AWC-ECU connector, C-47 intermediate connector, C-50 joint connector

Q. Is the check result normal?
Go to Step 4.
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 AWC-ECU connector terminal No. 9 and C-38 G and yaw rate sensor connector terminal No. 2, between C-46 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?
Go to Step 5.
Repair the wiring harness, and then go to Step 7.

STEP 5. Check whether the DTC is reset.

Q. Is DTC U1003 set?
Replace the G and yaw rate sensor. (Refer to .) Then go to Step 6.
Intermittent malfunction. (Refer to GROUP 00 - How to Cope with Intermittent Malfunction .)

STEP 6. Check whether the DTC is reset.

Q. Is DTC U1003 set?
Replace the hydraulic unit (incorporates in ASC-ECU). (Refer to .) Then go to Step 7.
The procedure is complete.

STEP 7. Check whether the DTC is reset.

Q. Is DTC U1003 set?
Return to Step 1.
The procedure is complete.