Conditions for Setting the DTC

WARNING: This page is about a different car, the 2006 Pontiac Montana SV6, 2006 Chevrolet Uplander, and 2006 Buick Terraza. However, it is still accessible from the selected car via links, so may be relevant.

The BCM detects a short to battery positive voltage, a short to ground, a poor connection or an open in the park lamp relay control circuit when it is trying to energize the park lamp relay.
A short to ground in the park lamp supply voltage circuit
An open in the park lamp relay coil
The condition above must be present for more than 0.3 seconds.