C123B

DTC C123B: Prolonged operation of ASC

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 or re-installed, always perform the 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 controls ASC by calculating the data sent from the wheel speed sensor, steering wheel sensor, and G and yaw rate sensor.

DTC SET CONDITIONS

This diagnostic trouble code is set when ASC control is operated for a prolonged period.

NOTE:
This diagnostic trouble code may be set when the vehicle runs on a slippery or rough road, or when the vehicle performs a steady state cornering.

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.

Using scan tool MB991958, 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).
After repairing the CAN bus line, 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 This diagnosis is complete.
STEP 3. Scan tool diagnostic trouble code

Check that DTCs 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 diagnostic trouble code 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 G and Yaw Rate Sensor Calibration). 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. Scan tool data list

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 Testing and Inspection).
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 Testing and Inspection).
Then go to Step 8.
STEP 8. Scan tool 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 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.

(1)Erase the DTC.

(2)Drive the vehicle at 12mph (20 km/h) or higher.

Q. Does ASC unnecessary activation occur or is the DTC C123B set?

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

(1)Erase the DTC.

(2)Drive the vehicle at 12mph (20 km/h) or higher.

Q. Does ASC unnecessary activation occur or is the DTC C123B set?

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