Inspection Procedure 5

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

COMMENT
The output shaft speed sensor signal or the throttle body is suspected.

TROUBLESHOOTING HINTS (THE MOST LIKELY CAUSES FOR THIS CASE:)
- Malfunction of the output shaft speed sensor.
- Malfunction of the throttle body.
- Malfunction of the PCM.

DIAGNOSIS

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

STEP 1. Using scan tool MB991958, read the diagnostic trouble code.

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.
2. Turn the ignition switch to the "ON" position.
3. Check for A/T system diagnostic trouble code. (refer to, A/T Diagnosis - Diagnostic Function - How to Read and Erase Diagnostic Trouble Code in Transmission Control Systems/Testing/Displaying & Reading Trouble Codes).
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4. Turn the ignition switch to the "LOCK" (OFF) position.
5. Disconnect scan tool MB991958.

Q: Is any DTC set?

YES: Repair the automatic transaxle control system. (Refer to, A/T Diagnosis - Diagnostic Trouble Code Chart in Transmission Control System/Testing/Trouble Code Descriptions). Then go to Step 4.

NO: Go to Step 2.

STEP 2. Using scan tool MB991958, read the diagnostic trouble code.

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.
2. Turn the ignition switch to the "ON" position.
3. Check for MFI system diagnostic trouble code. (Refer to, MFI Diagnosis - Diagnostic Function - How to Read and Erase Diagnostic Trouble Code). Reading Diagnostic Trouble Codes
4. Turn the ignition switch to the "LOCK" (OFF) position.
5. Disconnect scan tool MB991958.

Q: Is any DTC set?

YES: Repair the MFI control system. (Refer to MFI Diagnosis - Diagnostic Trouble Code Chart). Diagnostic Trouble Code Descriptions Then go to Step 4.

NO: Go to Step 3.

STEP 3. Check the symptoms.

Q: Does a hunting occur?

YES: Replace the PCM. Then go to Step 4

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

STEP 4. Check the symptoms.

Q: Does a hunting occur?

YES: Return to Step 1.

NO: The procedure is complete.