Inspection Procedure 8

Inspection Procedure 8: Hunting (Repeated Acceleration and Deceleration) Occurs at the Set Vehicle Speed. [M/T]

COMMENT
The vehicle speed sensor or the throttle body is suspected.

TROUBLESHOOTING HINTS (THE MOST LIKELY CAUSES FOR THIS CASE:)
- Malfunction of the vehicle speed sensor.
- Malfunction of the throttle body.
- Malfunction of the MFI system
- Malfunction of the ECM.

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A

STEP 1. Using scan tool MB991958, check for MFI system DTC.






CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.

1. Connect scan tool MB991958 to the data link connector. Scan Tool Connecting
2. Turn the ignition switch to the "ON" position.
3. Check for MFI system DTC. (Refer to Diagnostic Function.) Diagnostic Function [2.0L ENGINE Non-turbo> or (Refer to Diagnostic Function.) Diagnostic Function [2.4L ENGINE>.
4. Turn the ignition switch to the "LOCK" (OFF) position.
5. Disconnect scan tool MB991958.

Q: Is any DTC set?

YES : Diagnose the MFI system. (Refer to Diagnostic Trouble Code Chart. [2.0L ENGINE Non-turbo> Diagnostic Trouble Code Descriptions) or (Refer to Diagnostic Trouble Code Chart [2.4L ENGINE> Diagnostic Trouble Code Descriptions). Then go to Step 4.

NO : Go to Step 2.

STEP 2. Using scan tool MB991958, check data list item 04: Vehicle speed sensor.

1. Connect scan tool MB991958 to the data link connector. Scan Tool Connecting
2. Turn the ignition switch to the "ON" position.
3. Set scan tool MB991958 to data reading mode for cruise control system. Reading Diagnostic Trouble Codes
- Item 04: Vehicle speed sensor.

4. Turn the ignition switch to the "LOCK" (OFF) position.
5. Disconnect scan tool MB991958.

Q: Is the vehicle speed sensor operating properly?

YES : Go to Step 3.

NO : Replace the ECM. Then go to Step 4.

STEP 3. Retest the system

Q: Does hunting occur?

YES : Replace the ECM. Then go to Step 4.

NO : It can be assumed that this malfunction is intermittent.

STEP 4. Retest the system

Q: Does hunting occur?

YES : Return to Step 1.

NO : The procedure is complete.