Here's a breakdown:
* Reverse Switch: A switch, usually located on the transmission, is mechanically activated when the gear selector is moved into reverse.
* Wiring: This switch completes an electrical circuit. The circuit runs from the battery, through the switch, through a fuse (for protection), and then to the backup lights.
* Backup Lights: The lights themselves are simply bulbs (or LEDs in newer models) that illuminate when the circuit is completed and electricity flows through them.
* Ground: The circuit is completed by a ground connection, typically the car's chassis.
In short, shifting into reverse flips a switch, completing the electrical pathway, allowing electricity to flow to the backup lights, and making them turn on. If any part of this system (switch, wiring, fuse, bulb, ground) fails, the backup lights won't work.
