| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM connectors and ground circuits are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. |
Circuit Description
ECM operates Idle Air Control (IAC) valve to perform idle-up and provide feedback for target idling speed. DTC is set when idle speed continues to vary greatly from target speed. Possible causes are
- Idle Air Control (IAC) valve is stuck, or remains closed.
- IAC valve circuit is open or shorted.
- A/C switch circuit is open or shorted.
- Air induction system malfunction.
- Defective ECM.
Diagnostic Aids
Using scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.