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Inspection Procedure 15: HSA (Hill Start Assist) does not work.
 
 
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 (Refer to GROUP 54C - CAN Bus Diagnostics Table ).
  • Whenever ECU is replaced, ensure that the CAN bus lines are normal.
 
 
COMMENTS ON TROUBLE SYMPTOM
  • The slope gradient may be low.
  • The vehicle is not completely stationary.
  • A failure may have occurred in the calibration of the G and yaw rate sensor or brake fluid pressure sensor.
  • A defective parking brake may cause the HSA not to function.
  • A problem (noise interference) may have occurred in the CAN bus line, resulting in an improper communication with ASC-ECU or each ECU.
note
  • The HSA does not work even when the wheel speed sensor output pulse (vehicle moved) while the vehicle is parked.
  • The HSA is affected by the loading conditions and vehicle posture at the occurrence of phenomenon. When checking the HSA operation in actual driving, carry out the check on the vehicle with one occupant (driver) only.
 
 
 
TROUBLESHOOTING HINTS
  • Calibration failure of the G and yaw rate sensor
  • Calibration failure of the brake fluid pressure sensor
  • Malfunction of parking brake
  • Malfunction of wheel speed sensor
  • Malfunction of ETACS-ECU
  • Malfunction of hydraulic unit (integrated with ASC-ECU)
  • Wiring harness or connector failure of CAN bus line
  • Damaged wiring harness and connectors
 
 
 
 
DIAGNOSIS
STEP 1. HSA operation check.
Check if the HSA works with one occupant (driver) only in the vehicle.
Is the check result normal?
This diagnosis is complete.
Go to Step 2.
 
STEP 2. Parking brake check.
Does the brake warning lamp remain on after the parking brake is released?
Is the check result normal?
Go to Step 3.
Carry out Inspection procedure 3 "The brake warning light does not go out (ABS warning light is OFF) although the parking brake is released" (Refer to ).
 
STEP 3. Scan tool (M.U.T.-IIISE) CAN bus diagnostics.
(1)
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn off the power supply mode of the electric motor switch before connecting or disconnecting scan tool (M.U.T.-IIISE).
Connect scan tool (M.U.T.-IIISE). Refer to "How to connect the Scan Tool (M.U.T.-IIISE) ."
(2) Turn on the power supply mode of the electric motor switch.
(3) Diagnose the CAN bus line.
(4) Turn off the power supply mode of the electric motor switch.
Is the check result normal?
Go to Step 4.
Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ). Then go to Step 9.
 
STEP 4. Scan tool (M.U.T.-IIISE) DTC.
Use scan tool (M.U.T.-IIISE) to check the DTC for the ASC system.
Is the DTC set?
Carry out the diagnosis for the DTC (Refer to ).
Go to Step 5.
 
STEP 5. Scan tool (M.U.T.-IIISE) data list.
Check the PHEV-ECU system data list (Refer to GROUP 54Da - Troubleshooting, Data list reference table ).
  • Item No.04: Parking brake switch
  • Item No.303: Shift position (for control)
Is the check result normal?
Go to Step 6.
: Carry out the Inspection procedure 3 "The brake warning light does not go out (ABS warning light is OFF) although the parking brake is released" (Refer to ).
: Go to Step 9.
 
STEP 6. Scan tool (M.U.T.-IIISE) data list.
Check the following data list under curb weight condition or one occupant (driver) only in the vehicle, on a flat road (Refer to ).
  • Item No. 09: G sensor
  • Item No. 12: Yaw rate sensor
Is the check result normal?
Go to Step 7.
Carry out the calibration of the G and yaw rate sensor (Refer to ).
 
STEP 7. Scan tool (M.U.T.-IIISE) data list.
Check the following data list (Refer to ).
  • Item No. 10: Master cylinder pressure
Is the check result normal?
Go to Step 8.
Carry out the calibration of the brake fluid pressure sensor (Refer to ).
 
STEP 8. Scan tool (M.U.T.-IIISE) DTC.
Use scan tool (M.U.T.-IIISE) to check whether the DTC is set in the PHEV-ECU (related to the parking lock and clutch proportional valve).
Is the DTC set?
: Carry out the diagnosis for the DTC (Refer to GROUP 54Da - Troubleshooting ).
Go to Step 9.
 
STEP 9. Retest the system.
Check if the HSA works with one occupant (driver) only in the vehicle.
Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/How to Cope with Intermittent Malfunctions ).
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ).