Idle Speed/Throttle Actuator - Electronic: Description and Operation

PURPOSE
System permits Powertrain Control Module (PCM) control of bypass air through throttle body, improving idle stability, warm-up, and driveability.

Idle Air Control Bypass Air Valve:

Idle Air Control:

OPERATION
Bypass Air Control (BAC) valve consists of a PCM controlled Idle Air Control (IAC) valve and an Bypass Air (BPA) valve that opens and closes according to engine coolant temperature. The air valve is open on cold start and closes by the time operating temperature is reached. The idle air control valve is PCM controlled to allow bypass air compensation according to a number of inputs (engine temperature, load from P/S, A/C, and A/T).