Inspection Procedure 8: Hunting (Repeated Acceleration and Deceleration) Occurs at the Set Vehicle Speed <4B10-M/T>.


COMMENTS ON TROUBLE SYMPTOM



PROBABLE CAUSES



  • Malfunction of the vehicle speed sensor.
  • Malfunction of the throttle body.
  • Malfunction of the MPI system.
  • Malfunction of the engine-ECU.

DIAGNOSIS PROCEDURE

STEP 1. Check the MPI system diagnosis code.
Using M.U.T.-III, perform MPI system diagnosis code (Refer to GROUP 13B - Troubleshooting, Diagnosis Function ).

Q. Is any diagnosis code set?
Repair the MPI system (Refer to GROUP 13B - Troubleshooting, Inspection Chart for Diagnosis Trouble Code ). Then go to Step 4.
Go to Step 2.

STEP 2. 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 3.
Replace the engine-ECU (Refer to GROUP 13B - Engine-ECU ). When the Engine-ECU is replaced, register the encrypted code (Refer to GROUP 42C - Troubleshooting, ID Code Registration Necessity Judgment Table ). Then go to Step 4.

STEP 3. Retest the system

Q. Does a hunting occur?
Replace the engine-ECU (Refer to GROUP 13B - Engine-ECU ). When the Engine-ECU is replaced, register the encrypted code (Refer to GROUP 42C - Troubleshooting, ID Code Registration Necessity Judgment Table ). Then go to Step 4.
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 4. Retest the system

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