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




COMMENTS ON TROUBLE SYMPTOM




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 7.

STEP 2. Check the ASC system diagnosis code.


Using M.U.T.-III, perform ASC system diagnosis code.

Q. Is any diagnosis code stored?

Repair the ASC system (Refer to GROUP 35C - Troubleshooting, Diagnosis Code Chart ). Then go to Step 7.
Go to Step 3.

STEP 3. Check the A/T system diagnosis code.


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

Q. Is any diagnosis code stored?

Repair the A/T system (Refer to GROUP 23C - Troubleshooting, Diagnosis Code Chart ). Then go to Step 7.
Go to Step 4.

STEP 4. Check the diesel fuel system diagnosis code.


Using M.U.T.-III, perform diesel fuel system diagnosis code (Refer to GROUP 13D - Troubleshooting, Diagnosis Function ).

Q. Is any diagnosis code stored?

Repair the diesel fuel system (Refer to GROUP 13D - Troubleshooting, Inspection Chart for Diagnosis Trouble Code ). Then go to Step 7.
Go to Step 5.

STEP 5. Check the data list.


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

  • Item 04: Vehicle speed.

Q. Is the check result normal?

Go to Step 6.
Replace the engine-ECU (Refer to GROUP 13D - Engine-ECU ). Then go to Step 7.

STEP 6. Check the symptom.


Q. Does a hunting occur?

Replace the engine-ECU (Refer to GROUP 13D - Engine-ECU ). Then go to Step 7.
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 7. Check the symptom.


Q. Does a hunting occur?

Return to Step 1.
The procedure is complete.