Diagnostic Aids
WARNING: This page is about a different car, the 2003 GMC Sierra and 2003 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
Inspect for the following conditions:
- High resistance in an IAC valve control circuit.
- The correct PCV valve, properly installed and proper operation of the PCV valve.
- Proper operation and installation of all air intake components.
- Proper installation and operation of MAF sensor, if equipped.
- A tampered with or damaged throttle stop screw.
- A tampered with or damaged throttle plate, throttle shaft, throttle linkage, or cruise control linkage, if equipped.
- A skewed high TP sensor.
- Excessive deposits in the IAC passage or on IAC pintle.
- Excessive deposits in the throttle bore or on the throttle plate.
- Vacuum leaks.
- A high or unstable idle condition could be caused by a non-IAC system problem that cannot be overcome by the IAC valve.
- For intermittent conditions, see INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 4.3L SIERRA & SILVERADO article.