C123B
DTC C123B: Prolonged operation of ASCCAUTION:
^ 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 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 diagnostic trouble code is set when ASC operates for a prolonged period.
NOTE: When the vehicle runs on a slippery or rough road, or when the vehicle makes the steady turn, this diagnostic trouble code may be set.
PROBABLE CAUSES
^ Steering wheel sensor malfunction
^ G and yaw rate sensor malfunction
^ Improper installation of wheel speed sensor, 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
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. Diagnostic trouble code recheck after resetting CAN bus lines
Q: Is DTC C123B set?
YES: Go to Step 3.
NO: The procedure is complete.
STEP 3. M.U.T.-III 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 relevant diagnostic trouble codes, and then go to Step 10.
For C100A C100A
For C1015 C1015
For C1020 C1020
For C102B C102B
For C1011 C1011
For C101C C101C
For C1027 C1027
For C1032 C1032
For C1014 C1014
For C101F C101F
For C102A C102A
For C1035 C1035
For C1041 C1041
For C1042 C1042
For C1043 C1043
For C1044 C1044
For C1219 C1219
For C2205 C2205
For C123C C123C
For C2204 C2204
NO: Go to Step 4.
STEP 4. 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 5.
NO: Reinstall the G and yaw rate sensor correctly, and then go to Step 10.
STEP 5. M.U.T.-III data list
Check the following service data.
^ Item 08: Lateral G-sensor
^ Item 09: G-sensor [AWD]
^ Item 12: Yaw rate sensor
Q: Is the check result normal?
YES: Go to Step 6.
NO: Replace the G and yaw rate sensor, and then go to Step 10.
STEP 6. Steering wheel and steering wheel sensor installation check
1) Check whether a steering wheel other than a correct one is fitted.
2) Check that the steering wheel sensor is installed correctly.
Q: Is the check result normal?
YES: Go to Step 7.
NO: (Different steering wheel): Replace with the normal steering wheel. Then, go to Step 7.
NO: (Improper installation of steering wheel): 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 data list
Check the following service data.
^ Item 11: Steering angle
Q: Is the check result normal?
YES: Go to Step 9.
NO: Replace the wheel speed sensor, and then go to Step 10.
STEP 9. Check whether the diagnostic trouble code is reset.
Q: Is DTC C123B set?
YES: Replace the ASC-ECU. Then go to Step 10.
NO: Intermittent malfunction.
STEP 10. Check whether the diagnostic trouble code is reset.
Q: Is DTC C123B set?
YES: Return to Step 1.
NO: This diagnosis is complete.