Backup Lamp Relay: Description and Operation

The brake lamp relay is located in the underhood accessory fuse block in the engine compartment. The brake lamp relay is a micro relay and is contained within a small, rectangular, molded plastic housing. All of the required inputs and outputs are connected to 9 blades that extend from the bottom of the relay base.

The brake lamp relay uses a low current input from the illumination control module to control a high current output to the brake lamps. When the relay coil is energized, an electromagnetic field is produced by the coil windings. The field draws the moveable relay contact point away from the fixed normally open contact point and holds it against the fixed normally closed contact point.

The brake lamp relay terminals are connected to the vehicle electrical system through a connector receptacle in the underhood accessory fuse block.