| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM harness connector and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. If ECM is replaced, ECM must be programmed with proper ignition key code for engine immobilizer system. For programming procedures, see COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION. |
Circuit Description
Idle Air Control (IAC) valve is a rotary solenoid type and is located in front of air intake chamber. Intake air by-passing the throttle valve is directed to IAC valve through a passage. This allows air volume by-passing the throttle valve to be regulated. DTC P0505 is set if idle speed continues to vary greatly from target speed. Possible causes are
- IAC valve stuck or closed.
- Open or short in IAC valve circuit.
- Open or short in A/C signal circuit.
- Faulty air intake hose.
Diagnostic Aids
Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.