Inspection Procedure 8

Inspection Procedure 8: ASC OFF display stays ON after the engine is started.













CAUTION:

- If there is any problem in the CAN bus lines, an incorrect DTC 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 ASC OFF display or ASC OFF light to the combination meter through ETACS-ECU via CAN communication.

- By the operation of ASC OFF switch, the ASC OFF display or ASC OFF light 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 and the system cannot be turned OFF until the ignition switch is turned to the ON position next time.

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

- Malfunction of ETACS-ECU

- 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 A

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 10.
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).

- Item No.7: Indicator 1

Q. Is the check result normal?

YES Go to Step 4.
NO Replace the combination meter Removal and Replacement).
Then go to Step 9.
STEP 4. ASC OFF switch check

Refer to Testing and Inspection.

Q. Is the check result normal?

YES Go to Step 5.
NO Replace ASC OFF switch (Refer to Service and Repair). Then go to Step 10.
STEP 5. Connector check: C-313 ETACS-ECU connector, C-36 intermediate connector, C-45 ASC OFF switch connector

Q. Is the check result normal?

YES Go to Step 6.
NO Repair the damaged connector.
STEP 6. Wiring harness check between C-313 ETACS-ECU connector terminal No.15 and C-45 ASC OFF switch connector terminal No.1

- Check the power supply circuit for short circuit.

Q. Is the check result normal?

YES Go to Step 7.
NO Repair the wiring harness between C-313 ETACS-ECU connector terminal No.15 and C-45 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.

Q. Is the DTC set?

YES Diagnose the combination meter Combination Meter).
Then go to Step 10.
NO 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.

Q. Is the DTC set?

YES Perform troubleshooting on ETACS-ECU Electronic Time and Alarm Control System (ETACS)).
Then go to Step 9.
NO Go to Step 9.
STEP 9. Retest the system.

Q. Does ASC OFF display turn OFF normally?

YES Intermittent malfunction How to Cope With Intermittent Malfunctions).
NO Replace the hydraulic unit (integrated with ASC-ECU) (Refer to Active Stability Control System (ASC)).
Then go to Step 10.
STEP 10. Retest the system.

Q. Does ASC OFF display turn OFF normally?

YES The procedure is complete.
NO Return to Step 1.