Conditions for Setting the DTC: C0165
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 DTC sets when the EBCM detects an open in the stop lamp supply voltage circuit. The EBCM determines an open circuit if the voltage at the stop lamp supply voltage circuit is between 75 percent and 40 percent of ignition voltage.