Circuit Description
WARNING: This page is about a different car, the 2004 Pontiac Sunfire and 2004 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
The electronic brake control module (EBCM) sources 5 volts on the stop lamp switch signal circuit when the stop lamp switch is inactive. The voltage is supplied a ground path through the stop lamp bulbs.