Inspection Procedure 9
Inspection Procedure 9: ASC Operation Display Stays ON after the Engine is Started.
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 CAN Bus Line Diagnostics Flow ).
- Whenever ECU is replaced, ensure that the CAN bus lines are normal.
- 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 Testing and Inspection , Testing and Inspection and Testing and Inspection ).
OPERATION
- ASC-ECU sends the illumination request signal of the ASC indicator light to the combination meter through ETACS-ECU via the CAN communication.
COMMENTS ON TROUBLE SYMPTOM
This may be caused by faults in the CAN bus line, ETACS-ECU, combination meter or ASC-ECU.
PROBABLE CAUSES
- Damaged wiring harness and connectors
- ETACS-ECU malfunction
- Combination meter malfunction
- ASC-ECU malfunction
DIAGNOSIS
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 2.
NO Repair the CAN bus lines CAN Bus Diagnostics Chart).
Then go to Step 8.
STEP 2. Using scan tool MB991958, check the DTC
Use scan tool to check the DTC for the ASC system.
Q. Is the DTC set?
YES Carry out the diagnosis for the DTC (Refer to Active Stability Control System (ASC)).
NO Go to Step 3.
STEP 3. Actuator test of combination meter
Perform the following actuator test by the combination meter system, and check if the ASC OFF display or light illuminates normally Actuator Test Reference Table, Actuator Test Reference Table).
- Item No.13: Indicator 4
Q. Is the check result normal?
YES Go to Step 4.
NO Replace the combination meter Removal and Replacement).
Then go to Step 8.
STEP 4. Check the ASC-ECU power supply circuit system
Refer to Inspection Procedure 13.
Q. Is the check result normal?
YES Go to Step 5.
NO Diagnose the power supply circuit of the ASC-ECU Refer to Inspection Procedure 13.
STEP 5. Using scan tool MB991958, check the other system DTC
Using scan tool, check that DTC U0141 is not set by the combination meter system.
Q. Is the DTC set?
YES Diagnose the combination meter Refer to Combination Meter
Then go to Step 8.
NO Go to Step 6.
STEP 6. Using scan tool MB991958, check the other system DTC
Using scan tool, check that DTC U0121 is not set by the ETACS system.
Q. Is the DTC set?
YES
Perform troubleshooting on ETACS-ECU (Refer to Electronic Time and Alarm Control System (ETACS)).
Then go to Step 8.
NO Go to Step 7.
STEP 7. Retest the system.
Q. Does the ASC warning display turn OFF normally?
YES Intermittent malfunction How to Cope With Intermittent Malfunctions).
NO Replace the hydraulic unit (integrated with ASC-ECU) (Refer to Service and Repair).
Then go to Step 8.
STEP 8. Retest the system.
Q. Does the ASC warning display OFF normally?
YES The procedure is complete.
NO Return to Step 1.