Diagnostic Aids
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 1997 GMC Yukon, 1997 GMC Suburban, 1997 GMC Pickup, 1997 GMC Cab & Chassis, and 1997 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.
An intermittent may be caused by a poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect VCM harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness.
If connections and harness are okay, using DVOM connected between affected terminals and ground, monitor voltage while wiggling related connectors and wiring harness. If a failure is induced, voltage will change. A change in voltage will assist in isolating location of fault.