GM Genuine Parts Parking/Neutral Position and Backup Lamp Switchesare designed, engineered, and tested to rigorous standards, and are backed by General Motors. It is mounted on the transmission and allows your vehicle to start only in the park or neutral position. It also serves as the switch for your vehicle's backup lamps, turning them on when the car is placed into reverse. GM Genuine Parts are the true OE parts installed during the production of or validated by General Motors for GM vehicles. Some GM Genuine Parts may have formerly appeared as ACDelco GM Original Equipment (OE).