Possible Cause

Idle Air Control (IAC) valve controls engine speed and provides a dashpot function. IAC valve meters intake air around throttle plate through a bypass within IAC valve assembly and throttle body. PCM determines desired idle speed or bypass air and signals IAC valve through a specified duty cycle. The IAC valve responds by positioning to control amount of bypass air. Possible causes are:

• VPWR to IAC solenoid open (P0505, P1504 or P1507).
• IAC circuit open (P0505, P1504 or P1507).
• IAC circuit shorted to PWR (P0505, P1504 or P1507).
• IAC circuit shorted to GND (P1504).
• VPWR circuit open (P0505, P1504 or P1507).
• Air inlet plugged (P0505 or P1507).
• Air inlet leakage (P1507).
• Damaged IAC solenoid (P1504 or P1507).
• Damaged throttle body (P0505 or P1507).
• Damaged PCM (P0505, P1504 or P1507).