Inspection Procedure 9: The ASTC system cannot be disabled when ASC OFF switch is pressed to turn the system OFF.
| 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 - Troubleshooting
 ).
- Whenever ECU is replaced, ensure that the CAN bus lines are normal.
- When the hydraulic unit assembly (integrated with ASTC-ECU) is replaced, always carry out the calibration of the steering wheel sensor and the G sensor (Refer to ).
|
OPERATION
- The ASTC-ECU connector terminal (SWON) is earthed by pressing the ASC OFF switch.
- When the ASC OFF switch remains pressed for three seconds or more, the ASC control and the ATC control will be deactivated.
- When the ASC OFF switch remains pressed for 15 seconds or more, the ASC and the ATC systems will be activated.
COMMENTS ON TROUBLE SYMPTOM
This phenomenon may be caused by the open circuit in ASC OFF switch circuit.
PROBABLE CAUSES
- Malfunction of the ASC OFF switch
- Damaged wiring harness and connectors
- Malfunction of the hydraulic unit assembly (integrated with ASTC-ECU)
DIAGNOSIS PROCEDURE
STEP 1. Measure the resistance at the ASTC-ECU connector
|
|
(1)Check the ASTC-ECU connector.
|
|
|
(2)Disconnect the connector and measure at the wiring harness side.
|
|
|
(3)Measure the resistance between SWON terminal and body earth.
OK:
- When the ASC OFF switch is pressed: Continuity exists (2 Ω or less)
- When the ASC OFF switch is not pressed: No continuity
|
Q.
Is the check result normal?
Go to Step 4.
Go to Step 2.
STEP 2. Check the ASC OFF switch
Refer to .
Q.
Is the check result normal?
Go to Step 3.
Replace the ASC OFF switch (Refer to ). Then go to Step 5.
STEP 3. Measure the resistance at the ASC OFF switch connector
|
|
(1)Check the ASTC-ECU connector.
|
|
|
(2)Check the ASC OFF switch connector.
|
|
|
(3)Disconnect the connector and measure at the wiring harness side.
|
|
|
(4)Measure the resistance between ASTC-ECU connector SWON terminal and ASC OFF switch and resistance between ASC OFF switch and body earth.
OK: Continuity exists (2 Ω or less)
|
Q.
Is the check result normal?
Go to Step 4.
The circuit may be open. Repair the wiring harness wires or connectors between ASTC-ECU connector SWON terminal and ASC OFF switch and resistance between ASC OFF switch and body earth. Then go to Step 5.
STEP 4. Retest the system
Q.
Does the ASC OFF switch turn ON and OFF normally?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
Replace the hydraulic unit assembly (integrated with ASTC-ECU) (Refer to ).
STEP 5. Retest the system
Q.
Does the ASC OFF switch turn ON and OFF normally?
This diagnosis is complete.
Replace the hydraulic unit assembly (integrated with ASTC-ECU) (Refer to ).