SWITCH

A switch is an electrical component that opens or closes a circuit to turn a function on or off.

Operating it — by hand, pressure, temperature, or another input — connects or disconnects the contacts, controlling power to lights or motors, or a signal to a control unit.

Switches are used throughout a commercial vehicle's electrical system — dash controls, lighting, and pressure or temperature switches on the engine and brakes. Because some affect safety systems, electrical faults are best checked by a qualified technician.