U1003

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 CAN Bus Diagnostics Chart ).
- 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 (Refer to Testing and Inspection ).
- 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 (Refer to Testing and Inspection , Testing and Inspection and Testing and Inspection ).

CIRCUIT 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 ASC-ECU cannot receive the signal from the G and yaw rate sensor although there is no abnormality in ASC-ECU supply voltage.

PROBABLE CAUSES

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

DIAGNOSIS

STEP 1. Using scan tool MB991958, diagnose the CAN bus line.

Use scan tool MB991958 to diagnose the CAN bus lines.

Q. Is the check result normal?

YES Go to Step 3.
NO Repair the CAN bus lines CAN Bus Diagnostics Chart).
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-03 ASC-ECU connector, C-22 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-03 ASC-ECU connector terminals No.18 and C-22 G and yaw rate sensor connector terminals No.3, and between A-03 ASC-ECU connector terminals No.19 and C-22 G and yaw rate sensor connector terminals No.2.

Check for open and 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 DTC is reset.

Erase the DTC.

Q. Is DTC U1003 set?

YES Replace the G and yaw rate sensor (Refer to Service and Repair), and then go to Step 6.
NO The procedure is complete.
STEP 6. Check whether the DTC is reset.

Erase the DTC.

Q. Is DTC U1003 set?

YES Replace the hydraulic unit (integrated with ASC-ECU) (Refer to Service and Repair), and then go to Step 7.
NO The procedure is complete.
STEP 7. Check whether the DTC is reset.

Erase the DTC.

Q. Is DTC U1003 set?

YES Return to Step 1.
NO The procedure is complete.