Back-up Lights
FIGURE 39-15
Typical backup lights illuminated.

The back-up lights, also called reverse lights, are white lights mounted at the rear of a vehicle Figure 39-15. They provide the driver with vision behind the vehicle at night and also alert other drivers to the fact that the vehicle is in reverse. The lighting circuit consists of the battery, fuses and fusible links, the ignition switch, the back-up light (reverse) switch or a combined transmission back-up light/neutral safety switch on the transmission, back-up lamps, wiring to connect the components, and the ground circuit to allow current to return to the battery through the vehicle chassis.

When the ignition is on, and the vehicle is placed in reverse gear, the current flows from the battery, through the ignition switch, and through the closed reverse lamp or transmission position switch on the transmission. Electrical current then flows out of the closed switch to the back-up lamps and returns to the battery by the vehicle chassis ground circuit. Modern vehicles use network/bus systems and the BCM to command the back-up lights to come on.

Back-up lights are the only white lights on the rear of the vehicle. Since they operate only in reverse, other drivers can tell that the driver is backing up. This is why it is illegal to have broken tail/brake/turn signal lenses in the rear of the vehicle since white light would be visible, confusing other drivers.