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.
^ 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.
^ 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 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 M.U.T.-III, 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. 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. M.U.T.-III 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. 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. Then go to Step 5.
NO: Reinstall the G and yaw rate sensor correctly. Then go to Step 10.

STEP 5. M.U.T.-III service data
Check the following service data.
^ 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. 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. Then go to Step 7.

STEP 7. 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 8.
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 8.

STEP 8. M.U.T.-III service data
Check the following service data.
^ Item 11: Steering angle

Q: Is the check result normal?
YES: Go to Step 9.
NO: Replace the steering wheel sensor. Then go to Step 10.

STEP 9. Check whether the DTC is reset.

Q: Is DTC C123B set?
YES: Replace the hydraulic unit (ASC-ECU). Then go to Step 10.
NO: Intermittent malfunction.

STEP 10. Check whether the DTC is reset.

Q: Is DTC C123B set?
YES: Return to Step 1.
NO: The procedure is complete.