Circuit Description
WARNING: This page is about a different car, the 2000 Pontiac Firebird, 2000 Chevrolet Corvette, and 2000 Chevrolet Camaro. However, it is still accessible from the selected car via links, so may be relevant.
Idle Air Control (IAC) valve is controlled by PCM. PCM uses IAC to maintain a desired idle speed, which can vary depending on input to PCM and other criteria. If PCM detects that idle speed is out of IAC systems range of control at idle, it will perform an active test while vehicle is being driven.
During this test, PCM will command IAC valve to move while monitoring MAF. If expected change in MAF is detected, and IAC operation is verified, but since idle RPM is out of IAC system control and IAC valve is working, DTC P0506 will set. DTC P1508 will set, when there is no change in MAF, and IAC valve is functional, but idle RPM is out of IAC system control.
DTC will set when the following conditions are present:
- DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0125, P0171, P0172, P0174, P0175, P0300, P0401, P0404, P0405, P0443, P0500-P0503, P1120, P1220, P1221 or P1441 not set.
- Engine running greater than 60 seconds.
- ECT greater than 140°F (60°C).
- IAT greater than 14°F (-10°C).
- BARO greater than 65 kPa.
- Ignition voltage 9-18 volts.
- Vehicle speed less than one MPH.
- Actual idle speed is 100 RPM less than desired idle speed.
- Above conditions met for 5 seconds.