Inspection Procedure 7
INSPECTION PROCEDURE 7: Hunting (Repeated Acceleration and Deceleration) Occurs at the Set Vehicle SpeedCOMMENT
The secondary pulley speed sensor signal or the throttle body is suspected.
TROUBLESHOOTING HINTS (The most likely causes for this case:)
- Malfunction of the CAN bus line system.
- Malfunction of the secondary pulley speed sensor.
- Malfunction of the throttle body.
- Malfunction of the TCM.
- 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, diagnose the CAN bus line.
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. Diagnose the CAN bus line.
4. Turn the ignition switch to the "LOCK" (OFF) position.
5. Disconnect scan tool MB991958.
Q: Is the check result satisfactory?
YES : Go to Step 2
NO : Repair the CAN bus lines (Refer to Controller Area Network, Diagnosis - Can Bus Diagnostic Chart). Then go to Step 5.
STEP 2. Using scan tool MB991958, check for CVT system diagnostic trouble code.
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 CVT system diagnostic trouble code (Refer to CVT, Diagnosis - Diagnostic Function).
4. Turn the ignition switch to the "LOCK" (OFF) position.
5. Disconnect scan tool MB991958.
Q: Is any DTC set?
YES : Diagnose the CVT system (Refer to CVT, Diagnosis - Diagnostic Trouble Code Chart). Then go to Step 5.
NO : Go to Step 3.
STEP 3. Using scan tool MB991958, check for MFI system diagnostic trouble code.
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 diagnostic trouble code (Refer to MFI, Diagnosis - Diagnostic Function). Diagnostic Trouble Code Descriptions
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 MFI, Diagnosis - Diagnostic Trouble Code Chart). Then go to Step 5. Diagnostic Trouble Code Descriptions
NO : Go to Step 4.
STEP 4. Retest the system
Q: Does hunting occur?
YES : Replace the ECM. When the ECM is replaced, register the encrypted code (Refer to Wireless Control Module, Troubleshooting - ID Code Registration Judgment Table). Then go to Step 5.
NO : It can be assumed that this malfunction is intermittent (Refer to General (Body and Chassis), How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction).
STEP 5. Retest the system
Q: Does hunting occur?
YES : Return to Step 1.
NO : The procedure is complete.