Active Stability Control System (ASC)
DTC C123C: Abnormality in G and yaw rate sensor (lateral G or yaw rate)
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 Initial Inspection and Diagnostic Overview ).
- Whenever the ECU is replaced, ensure that the CAN bus lines are normal.
- When the steering wheel sensor is replaced, always perform calibration to make ASC-ECU learn the neutral point (Refer to Testing and Inspection ).
- 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 G and Yaw Rate Sensor Calibration ).
- When the hydraulic unit (integrated with ASC-ECU) is replaced, always perform the calibration of steering wheel sensor, G and yaw rate sensor, brake fluid pressure sensor, cut valve, and inlet valve (Refer to G and Yaw Rate Sensor Calibration , Testing and Inspection , Master Cylinder Brake Fluid Pressure Sensor Calibration , and Testing and Inspection ).
CIRCUIT 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 local CAN bus lines.
DTC SET CONDITIONS
This diagnostic trouble code is set if any malfunction below is found:
- Lateral G value or yaw rate value output from G and yaw rate sensor is abnormal.
- When abnormality is detected by comparing the value output from the lateral G and yaw rate 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
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?
YES Go to Step 2.
NO Repair the CAN bus lines CAN Bus Diagnostics Chart).
After repairing the CAN bus line, go to Step 2.
STEP 2. Check for diagnostic trouble codes of other systems
Check if diagnostic trouble code No. U0125 is also set in ASC-ECU.
Q. Is DTC U0125 set?
YES Perform troubleshooting for the diagnostic trouble code that is set (Refer to U0125).
Then go to Step 3.
NO Go to Step 3.
STEP 3. Check whether the DTC is reset.
Q. Is DTC C123C set?
YES Go to Step 4.
NO The procedure is complete.
STEP 4. Check of wheel speed sensor-related or steering wheel sensor-related diagnostic trouble code
Using scan tool MB991958, check if the wheel speed sensor-related or steering wheel sensor-related diagnostic trouble code is set (Refer to Active Stability Control System (ASC)).
Q. Is any DTC set?
YES Perform troubleshooting for the diagnostic trouble code that is set (Refer to Active Stability Control System (ASC)).
NO Go to Step 5.
STEP 5. Check of G and yaw rate sensor installation status
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, perform the calibration of the G and yaw rate sensor to make ASC-ECU relearn the neutral point (Refer to G and Yaw Rate Sensor Calibration).
Then go to Step 6.
NO Reinstall the G and yaw rate sensor correctly (Refer to Service and Repair).
Then go to Step 10.
STEP 6. Scan tool 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-05 ASC-ECU connector, C-46 AWC-ECU connector, C-47 intermediate 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-05 ASC-ECU connector terminal No. 18 and C-38 G and yaw rate sensor connector terminal No. 3, between A-05 ASC-ECU connector terminal No. 19 and C-38 G and yaw rate sensor connector terminal No. 2, between C-46 AWC-ECU connector terminal No. 9 and C-38 G and yaw rate sensor connector terminal No. 3, between C-46 AWC-ECU connector terminal No. 10 and C-38 G and yaw rate sensor connector terminal No. 2
- Open or short circuit check of communication circuit
Q. Is the check result normal?
YES Replace the G and yaw rate sensor (Refer to Service and Repair).
Then go to Step 12.
NO Repair the wiring harness, and then go to Step 13.
STEP 9. Check of steering wheel sensor installation status
Check that the steering wheel sensor is installed correctly.
Q. Is the check result normal?
YES Go to Step 10.
NO Install the steering wheel sensor correctly (Refer to Service and Repair).
Then go to Step 10.
STEP 10. Wheel alignment check
Front Suspension.
Q. Is the check result normal?
YES After checking the wheel alignment, perform the 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, perform the 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. Scan tool data list
Check the following data list (Refer to Data List Reference Table).
- Item 11: Steering angle sensor
Q. Is the check result normal?
YES Go to Step 12.
NO Replace the steering wheel sensor (Refer to Service and Repair).
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 (integrated with ASC-ECU) (Refer to Service and Repair).
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.