| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM connectors and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. |
Circuit Description
The ECM operates 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 stuck or closed.
- IAC valve circuit open or short.
- A/C switch circuit open or short.
- Air intake leak.
- ECM.