Diagnostic Aids
WARNING: This page is about a different car, the 2002 GMC Yukon XL, 2002 GMC Sierra, 2002 Chevrolet Suburban, and 2002 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
Check stoplamp switch for proper adjustment. Inspect wiring for poor connections at PCM and stoplamp switch. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wires that could short to bare metal or other wiring. Check for wires broken inside their insulation. If diagnosing for intermittent short or open conditions, move wiring harness while observing scan tool for value changes.