Inspection Procedure 9: ASC Operation Display Stays ON After the Engine Is Started
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 diagnosis 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 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 sends the illumination request signal of the ASC indicator lamp 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
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 2.
NO: Repair the CAN bus lines.
STEP 2. M.U.T.-III diagnostic trouble code
Use scan tool to check the diagnostic trouble code for the ASC system.
Q: Is the DTC set?
YES: Carry out the diagnosis for the diagnostic trouble code.
NO: Go to Step 3.
STEP 3. M.U.T.-III other system diagnostic trouble code
Using scan tool, check that the diagnostic trouble code U0141 is set by the combination meter system.
Q: Is the DTC set?
YES: Diagnose the combination meter. Then go to Step 5.
NO: Go to Step 4.
STEP 4. M.U.T.-III other system diagnostic trouble code
Using scan tool, check that the diagnostic trouble code U0121 is set by the ETACS system.
Q: Is the DTC set?
YES: Perform troubleshooting on ETACS-ECU. Then go to Step 5.
NO: Replace the ASC-ECU Then go to Step 5.
STEP 5. Retest the system.
Q: Does the ASC operation display turn ON and OFF normally?
YES: This diagnosis is complete.
NO: Return to Step 1.