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Inspection Procedure 6: ABS warning 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 stored. 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 ).
 
 
SYSTEM OPERATION
  • ASC-ECU sends the illumination request signal of the ABS warning light to the combination meter through ETACS-ECU via CAN communication.
  • ASC-ECU illuminates the ABS warning light via ETACS-ECU for approximately 3 seconds for valve check with the ignition switch turned to the ON position.
 
 
 
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
  • Control stop due to the low voltage
    noteDue to the abnormality in the supply voltage, the diagnostic trouble code may not be stored even when the ABS warning light is illuminated.
 
 
 
 
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 8.
 
STEP 2. Using scan tool MB991958, check the DTC
Use scan tool to check the DTC for the ASC system.
Is the DTC stored?
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 ABS warning light illuminates normally (Refer to GROUP 54A - Combination Meter/Actuator Test Table , ).
  • Item No.07: 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 8.
 
STEP 4. Check the ASC-ECU power supply circuit system.
Refer to .
Is the check result normal?
Go to Step 5.
Diagnose the power supply circuit of the ASC-ECU (Refer to ).
 
STEP 5. Using scan tool MB991958, check the other system DTC
Using scan tool, check that DTC U0141 is not stored in the combination meter system.
Is the DTC stored?
Diagnose the combination meter (Refer to GROUP 54A - Combination Meter/DTC ). Then go to Step 8.
Go to Step 6.
 
STEP 6. Using scan tool MB991958, check the other system DTC
Using scan tool, check that DTC U0121 is not stored in the ETACS system.
Is the DTC stored?
Perform troubleshooting on ETACS-ECU (Refer to GROUP 54A - ETACS/DTC ). Then go to Step 8.
Go to Step 7.
 
STEP 7. Retest the system.
(1) Erase the DTC.
(2) Drive the vehicle at 6 mph (10 km/h) or higher.
Does the ABS warning 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 ), and then go to Step 8.
 
STEP 8. Retest the system.
(1) Erase the DTC.
(2) Drive the vehicle at 6 mph (10 km/h) or higher.
Does the ABS warning light turn ON and OFF normally?
The procedure is complete.
Return to Step 1.