Diagnostic Aids

Inspect for the following conditions:

• High resistance in an IAC circuit.
• Restricted air intake system.
• Proper operation and installation of all air intake components.
• Collapsed, clogged, or loose air intake ducts.
• A clogged air filter.
• Proper operation of the Mass Airflow (MAF) sensor, if equipped.
• A tampered with or damaged throttle stop screw.
• A tampered with or damaged throttle plate, throttle shaft, or throttle linkage.
• Objects blocking the IAC passage or throttle bore.
• Excessive deposits in the IAC passage or on the IAC pintle.
• Excessive deposits in the throttle bore or on the throttle plate.
• Vacuum leaks.
• A low or unstable idle condition could be caused by a non-IAC system problem that can not be overcome by the IAC valve.

If the problem is determined to be intermittent, see INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 4.3L ASTRO, BLAZER, JIMMY CANADIAN, SAFARI, SONOMA & S10 PICKUP article.