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Inspection Procedure 14: 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.
 
 
 
PROBABLE CAUSES
  • 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 light 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. Using scan tool (M.U.T.-IIISE), diagnose the CAN bus line.
(1)
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn the ignition switch to the "LOCK" (OFF) position 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 the ignition switch to the "ON" position.
(3) Diagnose the CAN bus line.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the check result normal?
Go to Step 4.
Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ).
 
STEP 4. Using scan tool (M.U.T.-IIISE), check other 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. Using scan tool (M.U.T.-IIISE), check data list
Check the following data list (Refer to ).
  • Apply the parking brake.
 
Item No.Item nameNormal condition
29Parking brake switchON
Item No.Item nameNormal condition
29Parking brake switchON
  • Release the parking brake.
 
Item No.Item nameNormal condition
29Parking brake switchfrom "ON" to "OFF"
Item No.Item nameNormal condition
29Parking brake switchfrom "ON" to "OFF"
  • The selector lever is in the "R", "D", "N" and "P" position.
 
Item No.Item nameNormal condition
15Target gear
  • "R"
    • Selector lever: "R" position
  • "D"
    • Selector lever: "D" position
  • "P"
    • Selector lever: "P" position
  • "N"
    • Selector lever: "N" position
14Actual gear
Item No.Item nameNormal condition
15Target gear
  • "R"
    • Selector lever: "R" position
  • "D"
    • Selector lever: "D" position
  • "P"
    • Selector lever: "P" position
  • "N"
    • Selector lever: "N" position
14Actual gear
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. Using scan tool (M.U.T.-IIISE), check 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 06: Yaw rate sensor
  • Item 09: G sensor
Is the check result normal?
Go to Step 7.
Carry out the calibration of the G and yaw rate sensor (Refer to ). Then go to Step 9.
 
STEP 7. Using scan tool (M.U.T.-IIISE), check data list
Check the following data list (Refer to ).
  • Item 07: 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. Using scan tool (M.U.T.-IIISE), check other system DTC.
Use scan tool (M.U.T.-IIISE) to check that the DTC is set in the TCM.
Is the DTC set?
Carry out the diagnosis for the DTC (Refer to GROUP - 23A - Troubleshooting/Diagnostic Trouble Code Chart ).
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 ).