Inspection Procedure 7: Hunting (Repeated Acceleration and Deceleration) Occurs at the Set Vehicle Speed. <CVT>


COMMENTS ON TROUBLE SYMPTOM


The secondary pulley speed sensor signal (vehicle speed signal), or the throttle body is suspected.
note When the vehicle is driven with the low-speed gear in the sport mode, hunting occurs easily, however, this is not a failure.

PROBABLE CAUSES



DIAGNOSIS PROCEDURE
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.
  • Before replacing the ECU, ensure that the CAN bus lines is normal.

STEP 1. Check the CAN bus system diagnosis.
Using M.U.T.-III, perform CAN bus diagnosis (Refer to GROUP 54C - Explanation About The M.U.T-III Can Bus Diagnostics ).

Q. Is the check result satisfactory?
Go to Step 2.
Repair the CAN bus lines (Refer to GROUP 54C - Troubleshooting, Can Bus Diagnostic Table ). Then go to Step 6.

STEP 2. Check the CVT system diagnosis code.
Using M.U.T.-III, perform CVT system diagnosis code (Refer to GROUP 23A - Troubleshooting, Diagnosis Function ).

Q. Is any diagnosis code set?
Repair the CVT system (Refer to GROUP 23A - Troubleshooting, Inspection Chart for Diagnosis Code ). Then go to Step 6.
Go to Step 3.

STEP 3. Check the MPI system diagnosis code.
Using M.U.T.-III, perform MPI system diagnosis code (Refer to GROUP 13A - Troubleshooting, Diagnosis Function <4B1>, GROUP 13C - Troubleshooting, Diagnosis Function <4J1>).

Q. Is any diagnosis code set?
Repair the MPI system (Refer to GROUP 13A - Troubleshooting, Inspection Chart for Diagnosis Code <4B1>, GROUP 13C - Troubleshooting, Inspection Chart for Diagnosis Code <4J1>). Then go to Step 6.
Go to Step 4.

STEP 4. Check the data list.
Using M.U.T.-III, check the data list (Refer to data list reference table ).

  • Item 04: Vehicle speed signal

Q. Is the check result normal?
Go to Step 5.
Replace the engine-ECU (Refer to GROUP 13A - Engine-ECU <4B1>, GROUP 13C - Engine-ECU <4J1>). Then go to Step 6.

STEP 5. Check the symptom.

Q. Does a hunting occur?
Replace the engine-ECU (Refer to GROUP 13A - Engine-ECU <4B1>, GROUP 13C - Engine-ECU <4J1>). Then go to Step 6.
It can be assumed that this malfunction is intermittent (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points, How to Cope with Intermittent Malfunction ).

STEP 6. Check the symptom.

Q. Does a hunting occur?
Return to Step 1.
The procedure is complete.