Inspection Procedure 14

INSPECTION PROCEDURE 14: The engine stalls when decelerating.

COMMENT
- The intake air volume may be insufficient due to a defective electronic control throttle valve system.

TROUBLESHOOTING HINTS (The most likely causes for this case:)
- Malfunction of the electronic control throttle valve system.

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

STEP 1. Check if the battery terminal is disconnected.

Q: Has the battery terminal been disconnected lately?

YES: Start the engine and let it run at idle for approximate 10 minutes after engine warm up. Then if a malfunction occurs, go to step 2.

NO: Go to Step 2.




STEP 2. Using scan tool MB991958, read the diagnostic trouble code (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.
2. Turn the ignition switch to the "ON" position.
3. Read the DTC.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the DTC set?

YES: Refer to Diagnostic Trouble Code Chart. Diagnostic Trouble Code Descriptions

NO: Go to Step 3.




STEP 3. Using scan tool MB991958, check data list.

1. Turn the ignition switch to the "ON" position.
2. Check the following items in the data list. Refer to Data List Reference Table. Datal List Reference Table
a. Item 13: Throttle Position Sensor (main)
b. Item 15: Throttle Position Sensor (sub)
c. Item 11: Accelerator Pedal Position Sensor (main)
d. Item 12: Accelerator Pedal Position Sensor (sub)

3. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Are they operating properly?

YES: Go to Step 4.

NO: Repair or replace it. Then confirm that the malfunction symptom is eliminated.

STEP 4. Inspection of throttle body (throttle valve area) for dirtiness.

Q: Is the throttle valve area dirty?

YES: Refer to On-vehicle Service - Clean the throttle valve area.

NO: Check the following items, and repair, replace or clean the defective sections.
a. Check the ignition coil and spark plugs.
b. Check the EGR valve.

Then confirm that the malfunction symptom is eliminated.