Idle Control System

See IDLE AIR CONTROL (IAC) SOLENOID heading under SOLENOIDS  under RELAYS & SOLENOIDS. Curb idle and fast idle speed are controlled by Powertrain Control Module (PCM) and are not adjustable. Some throttle bodies have a sludge-tolerant design with a special coated throttle bore. A Yellow/Black warning decal on these units warns against backing off throttle plate adjustment screw to avoid throttle plate sticking in bore. Faults in idle control system components or circuit should set a service code. Refer to the QUICK TEST in the appropriate TESTS W/CODES - EEC-IV article in this section.