Circuit Description

PCM controls engine idle with Idle Air Control (IAC) valve. To increase idle speed, PCM commands pintle inside IAC valve away from throttle body seat, allowing more air to bypass throttle blade. To decrease idle speed, PCM commands pintle towards throttle body seat, reducing amount of air bypassing throttle blade. Scan tool will read IAC valve pintle position in counts. The higher the counts, the greater the air flow bypassing the throttle blade.

DTC will set if idle speed is greater than desired idle by more than 60 RPM for 13 seconds and when the following conditions are met:

• DTCs P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0125, P0128, P0130, P0131, P0132, P0133, P0134, P0171, P0172, P0201-P0204, P0300-P0304, P0336, P0440, P0442, P0446, P0452, P0453, P0480, P0481, P0502, P0503, P1133 and P1441 are not set.
• IAC command is less than 2 counts.
• BARO greater than 72 kPa.
• ECT greater than 104°F (40°C).
• Engine running more than 20 seconds.
• Idle stabilized for 5 seconds.
• Battery voltage 11.6-17.0 volts.