Circuit Description

PCM controls Idle Air Control (IAC) valve to regulate airflow through idle air by-pass passage. Idle speed is determined by the amount of air flowing through idle air by-pass passage. IAC valve is regulated according to engine load. A malfunctioning IAC valve could cause a stalling condition. DTC will set when PCM does not receive a closed signal from IAC valve after engine is started. When DTC sets, MIL will illuminate after 2 consecutive ignition cycles in which diagnostic runs with active fault. PCM will record operating conditions at time of failure and store information in FREEZE FRAME/FAILURE RECORDS data buffer.