A GPS unit is a great CAR accessory, but the power cord hanging across the dashboard is an eyesore. Many vehicles have 12V power at the rear-view mirror, with a 2-wire plug. Tap into it to straighten up your view.

You will need:

  • 12V power receptacle I used the Philmore TC600 cigarette lighter plug socket.
  • Wire, 2-conductor, insulated, 20-gauge solid, 6″ such as bell wire. Or 2 lengths of single-conductor wire.
  • Cable ties (5) aka zip ties
  • Wire cutter/stripper
  • Soldering iron and solder
  • Ohmmeter or multimeter


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Step #1: Wire your socket.

123 — Rear-View Power Socket

Unscrew the Philmore lighter socket to reveal the lugs. Strip 1/4" of insulation off all ends of your wire pair. Solder one wire to the center lug (+), and the other wire to one of the outer lugs (–). Reassemble the socket.

Step #2: Check polarity of the mirror plug wires.

123 — Rear-View Power Socket

Make sure your car is turned off. Use your ohmmeter to find continuity between a ground (such as the metal housing of the 12V socket in your dash) and one of the existing wires at the 12V mirror plug. The wire with zero resistance is the ground (–).

Step #3: Connect your socket.

123 — Rear-View Power Socket
  • Push your socket wires into the mirror plug, (–) to (–) and (+) to (+), making sure they make good contact. Zip-tie them to the plug wires so they stay put. (For a permanent connection, you could solder them.) Finally, zip-tie your new 12V socket securely in its hiding place.
  • Your new 12V socket behind the mirror is ready to power your GPS navigation unit, radar detector, or other gadgets that are suction-cupped to the windshield.
  • NOTE: If your mirror lacks a plug, try tapping into a courtesy light near the mirror.

Step #4: Going Further

123 — Rear-View Power Socket

To mount a gadget permanently, you could solder its wires to the plug, with no socket. But I wanted my GPS to be removable.

Doug Watson

Doug Watson

Doug Watson ([email protected]) is a fixer of all things broken; sometimes they’re even improved. He recently turned 52, and his brother thinks he's finally playing with a full deck.


  • Lisa Hartke

    That is awesome! Who knew? It won’t short out your cars electrical system will it?

    • Doug Watson

      Thanks. I have used it for over a year with no problems.

  • I know in Michigan they don’t like anything hanging from your car rearview mirror or even on the dash. Regardless of my views on the law, I think it’s important to let people know about the letter of the law.

    You may want to check your State’s laws before you mount this cool project on your dash or mirror.

    • Doug Watson

      You are right. Here in California, your GPS can only be mounted in the lower corners of the windshield and nothing can be hung from the mirror. Kooky laws, I guess you could suction cup mount it on the rearview mirror and not be in violation of the letter of the law that pertains to the windshield. Putting the GPS where the law states creates a worse blind spot. Before you know it they will outlaw those giant animal horns that people put on their hood. Next it will be no bumper stickers because they cause a distraction and then it will be all cars must be black or some other color the government chooses. Sorry to rant. The project is probably not legal everywhere.

      • Doug, I don’t see you writing as a rant, but a frustration with the absurdity of the laws on the books. My post is only to get the word out that this project, however cool, could wind up getting you a ticket on the road under circumstance of region and an officer’s proclivity to ticket.

        I know that this isn’t the first offense most law enforcement officers are going to look for; however, it is important for it to be known that one must check your local laws to see if it is legal to mount on the dash or on the mirror or really anywhere. I found both the post and the magazine article askew any mention of these concerns and thought it appropriate to supplement legal realities with the coolness of the project.