Diagnostic Aids
WARNING: This page is about a different car, the 2003 Buick Regal and 2003 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
Inspect wiring harness for poor connections at ISS, transaxle in-line 20-pin connector and PCM. Check for bent, backed out or damaged terminals, or for poor terminal tension. Check for chafed wiring. When diagnosing an intermittent condition, wiggle wiring harness while observing scan tool for change in value. Inspect transaxle in-line 20-pin connector for transaxle fluid. Check for Electromagnetic Interference (EMI) in ISS signal and ground circuits. EMI may be induced by a misrouted wiring harness along spark plug wires.