Diagnostic Aids
WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
Inspect wiring for poor connections. Check for bent, backed out or damaged terminals, or poor terminal tension. Check for chafed wire or broken wire inside insulation. When diagnosing intermittent condition, wiggle wiring harness while watching scan tool for change in value.