Inspection Procedure 9

Inspection Procedure 9: The skid control/TCL system cannot be disabled when ASC OFF switch is pressed for 3 seconds or more to turn the system OFF.













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.

OPERATION

- ETACS-ECU terminal No.15 is grounded by pressing ASC OFF switch. The ON/OFF state of ASC OFF switch is transferred from ETACS-ECU to ASC-ECU via CAN bus line.
- When the ASC OFF switch is pressed for 3 seconds or more, the ASC system turns OFF.
- When the ASC OFF switch is pressed and held for 15 seconds or more, ASC turns ON.

COMMENTS ON TROUBLE SYMPTOM

This may be caused by the open and short circuit in the ASC OFF switch circuit.

PROBABLE CAUSES

- Damaged wiring harness and connectors
- ASC OFF switch malfunction
- Malfunction of ETACS-ECU

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 7.
STEP 2. ASC OFF switch check

Refer to Testing and Inspection.

Q. Is the check result normal?

YES Go to Step 3.
NO Replace ASC OFF switch (Refer to Service and Repair). Then go to Step 7.
STEP 3. 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 4.
NO Repair the damaged connector.
STEP 4. Wiring harness check between C-313 ETACS-ECU connector terminal No.15 and C-45 ASC OFF switch connector terminal No.1

- Check the signal circuit for open and short circuit.

Q. Is the check result normal?

YES Go to Step 5.
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 5. Wiring harness check between C-45 ASC OFF switch connector terminal No.2 and the body ground

- Check the ground wires for open circuit.

Q. Is the check result normal?

YES Go to Step 6.
NO Repair the wiring harness between C-45 ASC OFF switch connector terminal No.2 and the body ground.
STEP 6. Retest the system.

Q. Does ASC turn ON and OFF normally using ASC OFF switch?

YES Intermittent malfunction How to Cope With Intermittent Malfunctions).
NO Replace the ETACS-ECU Electronic Time and Alarm Control System (ETACS)-ECU Removal and Installation).
Then go to Step 7.
STEP 7. Retest the system.

Q. Does ASC turn ON and OFF normally using ASC OFF switch?

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