Solenoids are relays that are commonly used to remotely switch a heavier current. By using a solenoid, the amount of heavy wiring needed to power the load is reduced since the control circuit typically uses a smaller gauge wire. Solenoids are used to control starter and winch motors but they also have other uses on a variety of vehicles. Grounded solenoids have one coil connection that is connected internally to the housing. The advantage of a grounded solenoid is that they require less wiring because the coil gets grounded from the housing. Grounded solenoids are ideal for areas where the mounting location is already grounded (or if it will be grounded to the battery) and for mounting areas that are not exposed to corrosive elements.