Diagnostic Aids
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 1994 GMC Vandura, 1994 GMC Rally, 1994 GMC Pickup, 1994 Chevrolet Sportvan, and 1994 Chevrolet Pickup. However, it is still accessible from the selected car via links, so may be relevant.
A slow, unstable idle may be caused by a system problem that cannot be overcome by IAC. Scan counts will be greater than 60 if too low, and zero counts if too high. If idle is too high, stop engine. With ignition on, ground ALDL test terminal "B". Wait 45 seconds for IAC to seat, then disconnect IAC. Start engine. If idle speed is greater than 800 RPM, inspect vehicle for vacuum leaks.