Inspection Procedure 5: Hunting (Repeated Acceleration and Deceleration) Occurs at the Set Vehicle Speed.


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 stored. 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 transmission system diagnosis code.
Using M.U.T.-III, perform transmission system diagnosis code (Refer to GROUP 23A - Troubleshooting, Diagnosis Function <CVT>, GROUP 23C - Troubleshooting, Diagnosis Function <A/T>).

Q. Is any diagnosis code stored?
Repair the transmission system (Refer to GROUP 23A - Troubleshooting, Inspection Chart for Diagnosis Code <CVT>, GROUP 23C - Troubleshooting, Inspection Chart for Diagnosis Code <A/T>). 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 13B - Troubleshooting, Diagnosis Function <6B3>).

Q. Is any diagnosis code stored?
Repair the MPI system (Refer to GROUP 13A - Troubleshooting, Inspection Chart for Diagnosis Code <4B1>, GROUP 13B - Troubleshooting, Inspection Chart for Diagnosis Code <6B3>). 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 13B - Engine-ECU <6B3>). 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 13B - Engine-ECU <6B3>). 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.