Diagnostic Aids
WARNING: This page is about a different car, the 2002 GMC Sierra, 2002 GMC Cab & Chassis Sierra, 2002 Chevrolet Silverado, and 2002 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
Inspect the wiring for poor electrical connections at the TCM. Look for a bent, backed-out or damaged terminal, poor terminal tension, a chafed wire or a broken wire inside the insulation. When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change. Drive the vehicle if necessary to experience a fault.