Inspection Procedure 6

INSPECTION PROCEDURE 6: 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 vehicle speed sensor [M/T].
- Malfunction of the output shaft speed sensor [A/T].
- Malfunction of the throttle body.
- Malfunction of the ECM [M/T] or PCM [A/T].

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, read the MFI system diagnostic trouble code [M/T].

(1)
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.

Connect scan tool MB991958 to the data link connector. (Refer to Reading and Clearing Diagnostic Trouble Codes).
(2)Turn the ignition switch to the "ON" position.
(3)Check for MFI system diagnostic trouble code Reading and Clearing Diagnostic Trouble Codes) [2.4L engine] or OBD-II Drive Cycle) [3.8L 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. Multiport Fuel Injection (MFI)) [2.4L engine] or
Multiport Fuel Injection (MFI)) [3.8L engine]. Then go to Step 5.

NO Go to Step 4.

STEP 4. Retest the system

Q. Does hunting occur?

YES Replace the ECM [M/T] or PCM [A/T]. Immobilizer System).
Then go to Step 5.
NO It can be assumed that this malfunction is intermittent. How to Cope With Intermittent Malfunctions).
STEP 5. Retest the system

Q. Does hunting occur?

YES Return to Step 1.
NO The procedure is complete.