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

The wheel speed sensor signal (vehicle speed signal) or the diesel fuel system is suspected.
The wheel speed sensor signal (vehicle speed signal) is transmitted from the ASC-ECU to the engine-ECU via the CAN bus line.

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.

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

	Go to Step 2.

	Repair the CAN bus lines (Refer to GROUP 54C - Troubleshooting, Can Bus Diagnostic Table ). Then go to Step 7.

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

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

	Go to Step 3.

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

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

	Go to Step 4.

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

	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.

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

	Go to Step 6.

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

	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 ).

	Return to Step 1.

	The procedure is complete.