A solenoid is an important part of a motor vehicle's electrical system that controls a push operation, pull operation or a function that both pushes and pulls. For instance, a solenoid is normally used to unlock car doors or pop the trunk remotely.
Solenoids serve several important functions in most vehicles. A vehicle's starter solenoid is normally attached to the starter of the engine, but it can also be mounted separately in a divorced solenoid setup. Vehicles with automatic transmission use a solenoid to control the flow of transmission fluid. First, the car's computer sends an electric charge to the solenoid, and then the solenoid activates the fluid distribution.