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Inspection Procedure 8: ASC OFF display or ASC OFF light 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 (Refer to GROUP 54C - CAN Bus Line Diagnostic 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 , and ).
 
 
OPERATION
  • ASC-ECU sends the illumination request signal of ASC OFF display to the combination meter through ETACS-ECU via CAN communication.
  • By the operation of ASC OFF switch, the ASC OFF display illuminates when the ASC function is stopped.
  • When the ASC OFF switch is pressed for 3 seconds or more, the ASC system turns OFF.
  • When the ASC OFF switch is pressed for 15 seconds or more, the ASC is kept in ON state.
 
 
 
TECHNICAL DESCRIPTION (COMMENT)
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
  • ASC OFF switch malfunction
 
 
 
 
DIAGNOSIS
STEP 1. Using scan tool MB991958, diagnose the CAN bus lines.
Use scan tool to diagnose the CAN bus lines.
Is the check result normal?
Go to Step 2.
Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ). Then go to Step 10.
 
STEP 2. Using scan tool MB991958, check the DTC
Use scan tool to check the DTC for the ASC system.
Is the DTC set?
Carry out the diagnosis for the DTC (Refer to ).
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 (Refer to GROUP 54A - Combination Meter/Actuator Test Table , ).
  • Item No.7: Indicator 1
Is the check result normal?
Go to Step 4.
Replace the combination meter (Refer to GROUP 54A - Combination Meter ). Then go to Step 9.
 
STEP 4. ASC OFF switch check
Refer to .
Is the check result normal?
Go to Step 5.
Replace ASC OFF switch (Refer to ). Then go to Step 10.
 
STEP 5. Connector check: C-412 ETACS-ECU connector, C-27 intermediate connector, C-30 ASC OFF switch connector
Is the check result normal?
Go to Step 6.
Repair the damaged connector.
 
STEP 6. Wiring harness check between C-412 ETACS-ECU connector terminal No.15 and C-30 ASC OFF switch connector terminal No.1
  • Check the power supply circuit for short circuit.
Is the check result normal?
Go to Step 7.
Repair the wiring harness between C-412 ETACS-ECU connector terminal No.15 and C-30 ASC OFF switch connector terminal No.1.
 
STEP 7. Using scan tool MB991958, check the DTC for other systems
Using scan tool, check that DTC U0141 is not set by the combination meter system.
Is the DTC set?
Diagnose the combination meter (Refer to GROUP 54A - Combination Meter/DTC ). Then go to Step 10.
Go to Step 8.
 
STEP 8. Using scan tool MB991958, check the DTC for other systems
Using scan tool, check that DTC U0121 is not set by the ETACS system.
Is the DTC set?
Perform troubleshooting on ETACS-ECU (Refer to GROUP 54A - ETACS/DTC ). Then go to Step 9.
Go to Step 9.
 
STEP 9. Retest the system.
Does ASC OFF display or ASC OFF light turn ON and OFF normally?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/How to Cope with Intermittent Malfunctions ).
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ). Then go to Step 10.
 
STEP 10. Retest the system.
Does ASC OFF display or ASC OFF light turn ON and OFF normally?
The procedure is complete.
Return to Step 1.