Inspection Procedure 17: The hill descent control does not work. <4WD>


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 ).

COMMENTS ON TROUBLE SYMPTOM


The hill descent control is not activated under any of the following conditions:

PROBABLE CAUSES



DIAGNOSIS PROCEDURE


STEP 1. M.U.T.-III CAN bus diagnosis


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

Q. Is the check result normal?

Go to Step 2.

Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting ). Then go to Step 4.

STEP 2. M.U.T.-III diagnosis code


Use M.U.T.-III to check the diagnosis code for the ASTC system.

Q. Is the diagnosis code set?

Carry out the diagnosis for the diagnosis code (Refer to ).

Go to Step 3.

STEP 3. Operate the hill descent control switch to check the system.


Is the hill descent control turned on when you operate the hill descent control switch while all of the following conditions are satisfied?

Q. Is the check result normal?

Go to Step 4.

Inspection Procedure 18: Proceed to "The hill descent control is not turned on or off by operating the hill descent control switch." (Refer to ). Then go to Step 4.

STEP 4. Retest the system


Is the hill descent control activated when you drive downhill on a non-gentle gradient at 20 km/h or less with the hill descent control turned on?

Q. Is the check result normal?

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 ).