Inspection Procedure 16: HSA (Hill Start Assist) works on a flat road.


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 - CAN Bus Diagnostics Table ).
  • Whenever ECU is replaced, ensure that the CAN bus lines are normal.

COMMENTS ON TROUBLE SYMPTOM

  • A failure may have occurred in the calibration of the G & yaw rate sensor.
  • Some drivers mistake a brake dragging for HSA operation.
  • If the suspension is modified, the vehicle posture changes, and the ASC-ECU judges that the vehicle is on a steep slope and may activate HSA.

PROBABLE CAUSES

  • ASC-ECU malfunction
  • Brake drag
  • Damaged wiring harness and connectors

DIAGNOSIS PROCEDURE

STEP 1. HSA operation check
Check if the HSA works on a flat road with one occupant (driver) only in the vehicle.

Q. Does the HSA work on a flat road?
Go to Step 2
This diagnosis is complete.

STEP 2. M.U.T.-III data list
Check the following data list (Refer to ).

  • Item 09: G sensor

Q. Is the check result normal?
Go to Step 3
Carry out the calibration of the G and yaw rate sensor (Refer to ). Then go to Step 4.

STEP 3. Brake drag check
Check the brake system for drag.

Q. Is the check result normal?
Go to Step 4
Repair the brake drag, and then go to Step 4.

STEP 4. Retest the system.
Check if the HSA works on a flat road with one occupant (driver) only in the vehicle.

Q. Does the HSA work on a flat road?
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ).
This diagnosis is complete.