How does an Accessory Relay Work?
Relays are a type of switch. When given a low draw electrical input, the relay's internal parts snap together, closing a circuit that requires a larger amount of electricity to power a specific component. When you add high draw accessories like onboard air systems, powerful stereo amplifiers, or power inverters you must incorporate a relay in order to avoid damaging the rest of your vehicle’s electrical system should something malfunction. Many vehicles are equipped with relays to help power factory supplied accessories, too.