C123C
DTC C123C: Abnormality in G and yaw rate sensorCAUTION:
^ 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 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.
^ 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.
^ 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.
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
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. M.U.T.-III CAN bus diagnostics
Use scan tool to diagnose the CAN bus lines.
Q: Is the check result normal?
YES: Go to Step 3.
NO: Repair the CAN bus lines. On completion, go to Step 2.
STEP 2. M.U.T.-III diagnostic trouble code
Check that the diagnostic trouble code U0125 is set in ASC-ECU.
Q: Is the diagnostic trouble code No.U0125 set?
YES: Troubleshoot for the diagnostic trouble code. Then go to Step 3.
NO: Go to Step 3.
STEP 3. Diagnostic trouble code 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 diagnostic trouble code.
Use scan tool to check whether the wheel speed sensor-related or steering wheel sensor-related diagnostic trouble code is set or not.
Q: Is any DTC set?
YES: Troubleshoot for the relevant diagnostic trouble code.
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, perform the calibration of the G and yaw rate sensor to make ASC-ECU relearn the neutral point. Then go to Step 6.
NO: Reinstall the G and yaw rate sensor correctly, and then go to Step 10.
STEP 6. M.U.T.-III data list
Check the following service data.
^ Item 08: Lateral G-sensor
^ Item 12: Yaw rate sensor
Q: Is the check result normal?
YES: Go to Step 7.
NO: Replace the G and yaw rate sensor, and then go to Step 10.
STEP 7. Steering wheel sensor installation check
Check that the steering wheel sensor is installed correctly.
Q: Is the check result normal?
YES: Go to Step 8.
NO: Reinstall the steering wheel sensor correctly, and then go to Step 8.
STEP 8. Wheel alignment check
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. Then go to Step 9.
NO: After adjusting the wheel alignment, perform the calibration of steering wheel sensor to make ASC-ECU relearn the neutral point. Then go to Step 9.
STEP 9. M.U.T.-III data list
Check the following service data.
^ Item 11: Steering angle sensor
Q: Is the check result normal?
YES: Go to Step 10.
NO: Replace the steering wheel sensor, and then go to Step 10.
STEP 10. Check whether the diagnostic trouble code is reset.
Q: Is DTC C123C set?
YES: Replace the ASC-ECU, and then go to Step 11.
NO: Intermittent malfunction.
STEP 11. Check whether the diagnostic trouble code is reset.
Q: Is DTC C123C set?
YES: Return to Step 1.
NO: This diagnosis is complete.