Diagnostic Aids
WARNING: This page is about a different car, the 1999 Pontiac Grand Am and 1999 Oldsmobile Alero. However, it is still accessible from the selected car via links, so may be relevant.
If battery voltage is found on the BCM parking lights relay output circuit, check relay and power to the relay. If DTC is history, problem may be intermittent. Perform test procedure while wiggling wiring and connectors.