A solenoid is a device that allows electrical currents to pass through it, which cause the solenoid to become magnetic. The coiled wires inside the solenoid that allow for the magnetic property change to occur can become damaged and stop working. In this event you will need to change it. A common place for this to happen is in the starter of your car where you have a starter solenoid mounted on the inside of the engine as well.
Remove the cables connecting to your car battery to avoid power surges or possible shocks while changing the solenoid.
Pull the top wire called the command wire out of the solenoid. This wire will usually have a colored plug connecting it to the solenoid.
Remove the nuts on the solenoid using a socket wrench. There are two nuts on the solenoid retaining the wires and a single nut above and to the side of the solenoid housing which attaches it to the inside of the car.
Inspect the wiring on the solenoid carefully so you can repeat it for the new one. Then remove the wiring by releasing the nuts holding it on.
Pull the solenoid out of the car and slip the replacement piece into its place. Make sure you arrange it just like the old one.
Hand-tighten all of the nuts onto the solenoid then tighten them with the wrench once you are sure of the positioning.
Set the wires onto the new solenoid posts and secure them with the new washers included with the replacement piece. Make sure you connect the wires exactly as they were on the old solenoid.
Tighten the wires and washers in place with the included new nuts and reconnect the command wire to complete the solenoid connections.
Reconnect the battery to the car.
