C123B

DTC C123B: Prolonged operation of ASC

CAUTION:

- If there is any problem in the CAN bus lines, an incorrect DTC 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.
- 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 Active Stability Control System (ASC) ).
- 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 Active Stability Control System (ASC) , Active Stability Control System (ASC) and Active Stability Control System (ASC) ).

OPERATION

ASC-ECU controls ASC by calculating the data sent from the wheel speed sensor, the steering wheel sensor, and the G and yaw rate sensor.

DTC SET CONDITIONS

This DTC is set when ASC operates for a prolonged period.

NOTE:
This DTC may be set when the vehicle runs on a slippery or rough road.

PROBABLE CAUSES

- Steering wheel sensor malfunction
- G and yaw rate sensor malfunction
- Improper installation of steering wheel sensor, or G and yaw rate sensor
- ASC-ECU malfunction
- Different steering wheel
- Wheel alignment not performed

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.

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 CAN Bus Diagnostics Chart).
On completion, go to Step 2.
STEP 2. DTC recheck after repairing the CAN bus line

Q. Is DTC C123B set?

YES Go to Step 3.
NO The procedure is complete.
STEP 3. Check the wheel speed sensor, and G and yaw rate sensor-related DTC.

Check that DTCs No.C100A, C1015, C1020, C102B, C1011, C101C, C1027, C1032, C1014, C101F, C102A, C1035, C1041, C1042, C1043, C1044, C1219, C2205, C123C, and C2204 are also set.

Q. Are DTCs C100A, C1015, C1020, C102B, C1011, C101C, C1027, C1032, C1014, C101F, C102A, C1035, C1041, C1042, C1043, C1044, C1219, C2205, C123C, and C2204 also set?

YES Carry out the diagnosis for the DTC that is set (Refer to Active Stability Control System (ASC)).
Then go to Step 10.
NO Go to Step 4.
STEP 4. 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 Active Stability Control System (ASC)). Then go to Step 5.
NO Reinstall the G and yaw rate sensor correctly (Refer to Service and Repair).
Then go to Step 10.
STEP 5. Using scan tool MB991958, check the service data

Check the following data list (Refer to Data List Reference Table).

- Item 08: Lateral G sensor
- Item 09: G sensor
- Item 12: Yaw rate sensor

Q. Is the check result normal?

YES Go to Step 6.
NO Replace the G and yaw rate sensor (Refer to Service and Repair). Then go to Step 10.
STEP 6. 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 7.
NO Install the steering wheel sensor correctly (Refer to Service and Repair).
Then go to Step 7.
STEP 7. 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 Active Stability Control System (ASC)).
Then go to Step 8.
NO After adjusting the wheel alignment, perform the calibration of steering wheel sensor to make ASC-ECU relearn the neutral point (Refer to Active Stability Control System (ASC)).
Then go to Step 8.
STEP 8. Using scan tool MB991958, check the service data

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 9.
NO Replace the steering wheel sensor (Refer to Service and Repair). Then go to Step 10.
STEP 9. Check whether the DTC is reset.

Q. Is DTC C123B set?

YES Replace the hydraulic unit (integrated with ASC-ECU) (Refer to Active Stability Control System (ASC)). Then go to Step 10.
NO Intermittent malfunction. How to Cope With Intermittent Malfunctions).
STEP 10. Check whether the DTC is reset.

Q. Is DTC C123B set?

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