Inspection Procedure No. 17 - Engine Vibrates When Decelerating
NOTE:
Possible causes are: defective idle air control motor system.
- Using scan tool, check for stored Diagnostic Trouble Codes (DTCs). If stored DTCs exist, perform appropriate test procedure for each DTC and clear DTCs from ECM. If no DTCs exist, go to next step.
- Ensure engine coolant temperature is less than 68°F (20°C). Turn ignition on. Listen for operating sound at idle air control motor when ignition is turned off. Idle air control motor is mounted on throttle body and uses a 6-pin Black connector.
- If idle air control motor operating sound is heard, go to next step. If idle air control motor operating sound is not heard, check idle control system. Perform DTC TEST NO. 24 under SELF-DIAGNOSTIC TESTS.
- Using scan tool, perform scan tool service data inspection procedure on throttle position sensor. See SCAN TOOL SERVICE DATA INSPECTION PROCEDURE at end of TROUBLE SYMPTOMS.
- If throttle position sensor operates correctly, go to next step. If throttle position sensor does not operate correctly, check throttle position sensor circuit. Perform DTC TEST NO. 5 under SELF-DIAGNOSTIC TESTS.
- Using scan tool, perform scan tool service data inspection procedure on closed throttle position switch. See SCAN TOOL SERVICE DATA INSPECTION PROCEDURE at end of TROUBLE SYMPTOMS.
- If closed throttle position switch does not operate correctly, check closed throttle position switch system. Perform DTC TEST NO. 25 under SELF-DIAGNOSTIC TESTS. If closed throttle position switch operates correctly, clean throttle body. See ADJUSTMENTS - TURBO article.