C123C
DTC C123C: Abnormality in G and yaw rate sensor [Abnormality in lateral G and yaw rate output value (incorrect installation)]
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 Line Diagnostics Flow ).
- Whenever ECU is replaced, ensure that the CAN bus lines are normal.
- When the steering wheel sensor is replaced, always carry out calibration to make ASC-ECU learn the neutral point (Refer to Testing and Inspection ).
- 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 ).
OPERATION
- ASC-ECU supplies power to the G and yaw rate sensor at the terminal No.1.
- The G and yaw rate sensor outputs the signal to ASC-ECU via the CAN bus lines.
DTC SET CONDITIONS
This diagnostic trouble code is set if any malfunction below is found:
- The output value of lateral G and yaw rate sensor is abnormal.
- When abnormality is detected by comparing the value output from the lateral G and yaw rate sensor with the one from the steering wheel sensor and wheel speed sensor
PROBABLE CAUSES
- Improper installation of the G and yaw rate sensor
- G and yaw rate sensor malfunction
- Steering wheel sensor malfunction
- Improper installation of steering wheel sensor
- Malfunction of wheel speed sensor
- ASC-ECU malfunction
- External noise interference
DIAGNOSIS
STEP 1. Using scan tool MB991958, diagnose the CAN bus lines.
Use scan tool to diagnose the CAN bus lines.
Q. Is the check result normal?
YES Go to Step 2.
NO Repair the CAN bus lines CAN Bus Diagnostics Chart).
On completion, go to Step 2.
STEP 2. Using scan tool MB991958, DTC
Check that the DTC U0125 is set in ASC-ECU.
Q. Is DTC U0125 set?
YES Troubleshoot for the DTC (Refer to U0125). Then go to Step 3.
NO Go to Step 3.
STEP 3. DTC recheck after resetting CAN bus lines
Q. Is DTC C123C set?
YES Go to Step 4.
NO The procedure is complete.
STEP 4. Check the wheel speed sensor-related or steering wheel sensor-related DTC.
Use scan tool to check whether the wheel speed sensor-related or steering wheel sensor-related DTC is set or not.
Q. Is the DTC set?
YES Troubleshoot for the relevant DTC (Refer to Active Stability Control System (ASC)).
NO Go to Step 5.
STEP 5. G and yaw rate sensor installation check
Check that the G and yaw rate sensor is installed correctly.
Q. Is the check result normal?
YES After checking the G and yaw rate sensor, carry out calibration of the G and yaw rate sensor to make ASC-ECU relearn the neutral point (Refer to Testing and Inspection). Then go to Step 6.
NO Reinstall the G and yaw rate sensor correctly (Refer to Service and Repair), and then go to Step 12.
STEP 6. M.U.T.-III data list
Check the following data list (Refer to Data List Reference Table).
- Item 08: Lateral G-sensor
- Item 12: Yaw rate sensor
Q. Is the check result normal?
YES Go to Step 9.
NO Go to Step 7.
STEP 7. 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 8.
NO Repair the connector, and then go to Step 13.
STEP 8. Wiring harness check between A-03 ASC-ECU connector terminal No. 18 and C-22 G and yaw rate sensor connector terminal No. 3 as well as between A-03 ASC-ECU connector terminal No. 19 and C-22 G and yaw rate sensor connector terminal No. 2
- Check the communication circuit for open and short circuit.
Q. Is the check result normal?
YES Replace the G and yaw rate sensor (Refer to Service and Repair), and then go to Step 12.
NO Repair the wiring harness, and then go to Step 13.
STEP 9. Steering wheel sensor installation check
Check that the steering wheel sensor is installed correctly.
Q. Is the check result normal?
YES Go to Step 10.
NO Reinstall the steering wheel sensor correctly (Refer to Service and Repair), and then go to Step 10.
STEP 10. Wheel alignment check
Service and Repair.
Q. Is the check result normal?
YES After checking the wheel alignment, carry out calibration of steering wheel sensor to make ASC-ECU relearn the neutral point (Refer to Testing and Inspection). Then go to Step 11.
NO After adjusting the wheel alignment, carry out calibration of steering wheel sensor to make ASC-ECU relearn the neutral point (Refer to Testing and Inspection). Then go to Step 11.
STEP 11. M.U.T.-III data list
Check the following data list (Refer to Data List Reference Table).
- Item 11: Steering angle
Q. Is the check result normal?
YES Go to Step 12.
NO Replace the steering wheel sensor (Refer to Service and Repair), and then go to Step 12.
STEP 12. Check whether the DTC is reset.
(1)Erase the DTC.
(2)Drive the vehicle at 12mph (20 km/h) or higher.
Q. Is DTC C123C set?
YES Replace the hydraulic unit (ASC-ECU) (Refer to Service and Repair), and then go to Step 13.
NO Intermittent malfunction How to Cope With Intermittent Malfunctions).
STEP 13. Check whether the DTC is reset.
(1)Erase the DTC.
(2)Drive the vehicle at 12mph (20 km/h) or higher.
Q. Is DTC C123C set?
YES Return to Step 1.
NO The procedure is complete.