Inspection Procedure 5: ABS warning lamp 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 (Refer to GROUP 54C, Trouble code diagnosis ).
  • Whenever ECU is replaced, ensure that the CAN bus lines are normal.

OPERATION

  • ABS-ECU sends the illumination request signal of the ABS warning lamp to the combination meter through ETACS-ECU via CAN communication.
  • ABS-ECU illuminates the ABS warning lamp via ETACS-ECU for approximately 3 seconds for valve check with the ignition switch turned to the ON position.

COMMENTS ON TROUBLE SYMPTOM
This may be caused by faults in the CAN bus line, ETACS-ECU, combination meter or ABS-ECU.

PROBABLE CAUSES

  • Damaged wiring harness and connectors
  • Malfunction of ETACS-ECU
  • Malfunction of combination meter
  • Malfunction of ABS-ECU
    note Due to the abnormality in the supply voltage, the diagnosis code may not be set even when the ABS warning lamp is illuminated.

DIAGNOSTIC PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics
Use M.U.T.-III to diagnose the CAN bus lines.

Q. Is the check result normal?
Go to Step 2.
Repair the CAN bus lines. (Refer to GROUP 54C - CAN Bus Diagnosis table .) Then go to Step 7.

STEP 2. M.U.T.-III diagnosis code
Use M.U.T.-III to check the diagnosis code for the ABS system.

Q. Is the diagnosis code set?
Carry out the diagnosis for the diagnosis code. (Refer to .)
Go to Step 3.

STEP 3. Check the ABS-ECU power supply circuit system.
Refer to .

Q. Is the check result normal?
Go to Step 4.
Carry out the diagnosis of ABS-ECU power supply circuit system.(Refer to .)

STEP 4. M.U.T.-III diagnosis code for other systems
Using M.U.T.-III, check that diagnosis code No. U0141 is set by the combination meter system.

Q. Is the diagnosis code set?
Diagnose the combination meter. (Refer to GROUP 54A - Combination Meter, Troubleshooting .) Then go to Step 7.
Go to Step 5.

STEP 5. M.U.T.-III diagnosis code for other systems
Using M.U.T.-III, check that diagnosis code No. U0121 is set by the ETACS system.

Q. Is the diagnosis code set?
Perform troubleshooting on ETACS-ECU. (Refer to GROUP 54A - ETACS, Troubleshooting .) Then go to Step 7.
Go to Step 6.

STEP 6. Retest the system.

Q. Does the ABS warning lamp turn ON and OFF normally?
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction .)
Replace the ABS-ECU (Refer to ). Then go to Step 7.

STEP 7. Retest the system.

Q. Does the ABS warning lamp turn ON and OFF normally?
This diagnosis is complete.
Return to Step 1.