Inspection Procedure 8: After the ASC Off Switch Is Pressed to Turn "Off," the Stability Control/TCL Cannot Be Cancelled.

Inspection Procedure 8: After the ASC OFF switch is pressed to turn "OFF," the stability control/TCL cannot be cancelled.














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.
^ Whenever the ECU is replaced, ensure that the CAN bus lines are normal.

SYSTEM OPERATION
^ The ETACS-ECU terminal No. 15 is grounded when the ASC OFF switch is pressed. The ON/OFF status of ASC OFF switch is sent from ETACS-ECU to ASC-ECU via CAN bus line.
^ When the ASC OFF switch is pressed shortly, the ASC system is turned OFF.
^ When the ASC OFF switch is pressed and held for 15 seconds or more, the ASC OFF indicator light is turned off, and the ASC system is turned ON.

TECHNICAL DESCRIPTION (COMMENT)
In the case of this trouble symptom, there may be an open and short circuit to the ASC OFF switch circuit.

PROBABLE CAUSES
^ Damaged wiring harness and connectors
^ ASC OFF switch malfunction
^ ETACS-ECU malfunction
^ Combination meter 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.
Using scan tool MB991958, diagnose the CAN bus lines.
Q: Is the check result normal?
YES: Go to Step 2.
NO: Repair the CAN bus lines. (Refer to Troubleshooting Can Bus Diagnostics Table.) After repairing the CAN bus line, go to Step 8.

STEP 2. ASC OFF switch check
Q: Is the check result normal?
YES: Go to Step 3.
NO: Replace the ASC OFF switch. Then, go to Step 8.

STEP 3. Connector check: C-313 ETACS-ECU connector, C-42 intermediate connector, C-135 ASC OFF switch connector
Q: Is the check result normal?
YES: Go to Step 4.
NO: Repair the defective connector.

STEP 4. Wiring harness check between C-313 ETACS-ECU connector terminal No. 15 and C-135 ASC OFF switch connector terminal No. 1
^ Check the power supply 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-135 ASC OFF switch connector terminal No. 1.

STEP 5. Wiring harness check between C-135 ASC OFF switch connector terminal No. 2 and the body ground
^ Open circuit check of the ground circuit
Q: Is the check result normal?
YES: Go to Step 6.
NO: Repair the wiring harness between C-135 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 the ASC OFF switch?
YES: Intermittent malfunction.
NO: Replace the ETACS-ECU. Then, go to Step 7.

STEP 7. Retest the system.
Q: Does ASC turn ON and OFF normally using the ASC OFF switch?
YES: The procedure is complete.
NO: Replace the combination meter. Then, go to Step 8.

STEP 8. Retest the system.
Q: Does ASC turn ON and OFF normally using the ASC OFF switch?
YES: The procedure is complete.
NO: Return to Step 1.