To minimise the mess of wires running around the interior of your vehicle, wire your Tom Tom directly into the power supply and hide the wires behind the dashboard. You can easily accomplish this project if you have a basic knowledge of how an automobile electrical system works.
Open your vehicle's interior fuse panel. The owners manual can provide the exact location.
Mount the GPS in a location that is both easy to reach and preferably close to the fuse panel. Attach the Tom Tom's supplied power wire and run it along the gap between the glass and the dashboard in the direction of the fuse panel.
Connect the Tom Tom's outlet plug into the new female 12-volt outlet socket
Attach the fuse holders positive wire (red) to the positive wire for the female outlet plug with a butt connector. A butt connector works by placing one stripped wire in each end and compressing with the pliers. Gently tug on the connection to assure a tight fit.
Attach the fuse holder's other positive wire to a fuse tap using a butt connector.
Attached the negative wire from the 12-volt outlet to the vehicle's bare metal body. A good spot will be close to the fuse panel and possibly under a bolt. Modern automobiles use the metal frame and body of the vehicle for their ground connections.
Push the fuse tap into an empty fuse slot and put a 10 amp fuse into the holder.
Wrap all of the connections in electrical tape and secure any loose wires with cable ties.
Detach the positive connection to the vehicle's battery before beginning work.