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 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.
^ 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.
^ 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.
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. (Refer to Troubleshooting Can Bus Diagnostics Table.) 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 Diagnostic Trouble Code Descriptions.) 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. Scan tool service data
Check the following service data. (Refer to Scan Tool Testing and Procedures.)
^ 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
Refer to On-vehicles service Testing and Inspection.
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. Scan tool service data
Check the following service data. (Refer to Scan Tool Testing and Procedures.)
^ 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.
Drive the vehicle for 15 seconds or more at 25 mph (40 km/h) or higher.
Q: Is DTC C123B set?
YES: Replace the hydraulic unit (incorporates in ASC-ECU). Then go to Step 10.
NO: Intermittent malfunction.
STEP 10. Check whether the DTC is reset.
Drive the vehicle for 15 seconds or more at 25 mph (40 km/h) or higher.
Q: Is DTC C123B set?
YES: Return to Step 1.
NO: The procedure is complete.