Mercedes Benz OEM rear wiper relay A1405420019 W140 S280 S420 S500 S600

A relay in a car is an electrical component that acts as a switch. It is typically used to control high-current circuits or circuits connected to different voltage levels.

The relay works by using a low-current signal to activate an electromagnet that, in turn, closes or opens the contacts of the relay. This enables the relay to control power flow to various components in the car.