Diagnostic Aids
WARNING: This page is about a different car, the 2003 Cadillac Seville and 2003 Cadillac DeVille. 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.
- Proper operation and installation of all air intake components.
- Correct Positive Crankcase Ventilation (PCV) valve, properly installed and proper operation of PCV valve (if equipped).
- Proper installation and operation of the Mass Airflow (MAF) sensor, if equipped
- Tampered with or damaged throttle stop screw.
- Tampered with or damaged throttle plate, throttle shaft, throttle linkage, or cruise control linkage (if equipped).
- A skewed high Throttle Position (TP) sensor.
- Excessive deposits in IAC passage or on IAC pintle.
- Excessive deposits in throttle bore or on 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. Refer to SYMPTOMS under TROUBLE SHOOTING - NO CODES article.
- If the problem is determined to be intermittent, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 4.6L DEVILLE & SEVILLE article.