Diagnostic Aids
WARNING: This page does not describe the selected car, but rather 14 other vehicles, including the 1998 GMC Savana Special, 1998 GMC Savana Camper Special, 1998 GMC Savana, 1998 Chevrolet RV Cutaway, and 1998 Chevrolet Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
Inspect wiring for poor connections at VCM, transmission 20-pin connector and speed sensor. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change. First diagnose and clear any engine or TP sensor DTCs that are present, then inspect for any transmission DTCs that may have reset. Check for misrouted sensor harness. Wiring may be near DIS components or ignition wires.