1st Gen "How To" How To: Car Electronic Device Hard Wire (radar detector)

By Mol · Jan 27, 2018 ·
  1. Mol
    How To: Car Electronic Device Hard Wire (radar detector)

    by Molly "pi" Smith (aka Mol)
    Images by the Author

    (formerly Molly Bunton, soon to be Molly Notle)

    I am a real gizmo geek and I have a few how-tos on my blog. I hope to add more as time permits.

    I hope some of you find this useful:
    Car Electronic Device Hard Wire (radar detector)

    I recently added a window mounted electronic device to my MINI. I’ve mounted the device up by the rear view mirror and I did not like the power cord, which plugged into the cigarette lighter, cluttering my window and dash. I decided to hard wire the device, thus eliminating all visual wires.

    It was not hard, or terribly time consuming, and I was extremely pleased with the results. I’ll share with you my step-by-step procedure and you can adapt this to suit your own hard wiring needs, such for as a GPS, iPod or the like.

    mounted device
    Fully hard wired window mounted electronic device

    I first tried to hard wire the device to the map lights up by the rear view mirror, but nothing I tried would work correctly to completely power this particular device: a Passport 8500. I did get some power, but not enough to get the device to work. So, I decided to hard wire directly through the fuse box.

    Note: My device has a remote mute button, which made this project just a tad more technical than if there was just one wire to deal with.

    I prepared for this project by purchasing the Direct-wire Smart Cord that is made for this product. Do not try to adapt the Standard coiled cord that comes with the Passport unit because it will just ruin the cord. Believe me, I tried to adapt the Standard cord to no avail, and I am good at electronic type stuff.

    Your device may be easier to adapt and you may or may not have to purchase a special cord.


    First, I purchased an Add-A-Circuit. Don’t bother trying to get one at Radio Shack. They are useless nowadays for anything but cell phone related stuff. They had no idea what I was talking about, even though I knew exactly what I needed. They sold me something else that was completely useless. I then went across the street to Auto Zone and found exactly what I wanted. I think you may be able to get these at Wal-Mart, though I am not sure. They do not have them at Lowes.

    I prepared the cord before starting.


    The Add-A-Circuit has the red wire. My special cord had a flat male plug on the end.

    I simply cut off the plug, stripped the cord and crimped the two cords together.


    I plugged a 5 amp fuse into the correct space for the secondary circuit on the Add-A-Circuit (refer to the instructions!)

    I then cut the plug from the ground wire and stripped about one inch of wire.

    Now I am ready to wire the MINI.

    First: I turned off the electricity in my vehicle by disconnecting the battery. The MINI Cooper S comes with a nice little tool kit nestled next to the battery. I used the supplied wrench to loosen and removed the negative terminal contact (purple arrow in photo below).


    There is a tool in the kit used to remove the round tow hook covers on the front and back of the MINI (green arrow in photo above). This tool came in really handy later in poking the wire.

    Now the hardest part first. I needed to connect the ground wire to the vehicle body. You need to find a good screw/bolt that connects to an unpainted part of the main vehicle body. I chose a good bolt behind the steering wheel. See the photo below and the green arrow. To get to this you need to contort yourself totally upside down in the drivers side foot area. You need to look straight up behind the steering wheel. I have a flashlight that straps to my head and this was invaluable for this task. Reaching the bolt was a one handed deal. Be patient. I loosened the bolt enough to wrap the groud wire around it. I gave myself a good amount of stripped wire and wound it all the way around the bolt before retightening well. I made sure the wire had good, solid contact with the unpainted body frame.

    Bolt near the steering column

    In the MINI, the fuse panel is in the drivers side leg area. Now, I opened the fuse box panel and ran the “hot” wire down to the fuse box, using cable ties to keep the wire neat and out of the way of any moving parts. I ran the wire into the fuse box from the back. I found a 5 amp circuit that will turn off when I turned off my car. Not all circuits do this. The circuit cannot be any of the circuits in the bottom two rows on the right side because the Add-A-Circuit will not fit if installed properly (it will fit if inproperly installed). I chose a spot in the niddle of the left column: the rear windshield wiper, which was “F11″ in my 2005 MINI S.

    2005 MINI Cooper S fuse map

    I removed the “main” fuse from my chosen circuit using the fuse puller that is housed in the lower fuse panel. Do not install the “main” fuse you removed into the Add-A-Circuit yet. You need to check the new device wiring is correct first before you reinstall removed fuse.

    I inserted the Add-A-Circuit into the space where I had removed the fuse. Unlike with just a single fuse, where which direction you install it is not that important, with the two fuses in the Add-A-Circuit, there is a right way and wrong way to install it.� You want the fuses properly protecting your devices in the correct order. The wire on the Add-A-Circuit needs to point with the wire pointing “away” from the fuse row: to the outside of the chosen fuse row.
    i.e.: If you chose the left side, the wire points left and the circuit points “up”. If you chose the right column, the wire points right and the circuit points “down”. (This is why you cannot use the bottom two rows on the right side.)

    Fuse panel with Add-A-Circuit

    Now to test the wiring before going any further. I plugged in my device (not mounted at this point) and reattached the battery. I turned on the power on to the vehicle and saw if the device powered up. For me, it did, but if it doesn’t for you, discount the battery and check your wiring. Check the ground, check your fuse. Made sure you have the Add-A-Circuit install facing the correct direction. Make sure your “secondary” fuse is in the correct slot on the Add-A-Circuit. Reattach the battery and make sure it is attached correctly. Turn on the power again and see. If it doesn’t work, choose another fuse/circuit to tap into and try again.

    Once you have the device powering on ok, turn off the power to the car and see if the device goes off. If not, choose another fuse/circuit to tap into.

    Once everything is powering on and off correctly, you install the “main” fuse you had removed. I now have two fuses in the Add-A-Circuit.

    Now, I mounted my device, ran and hid the wires. I poked the wire under the rubber around the door, up the A pillar, then around the pillar where it meets the headliner. You can use a poking tool of some sort. This is where I found the tow hook tool came in real handy. See the red line in the following photos.

    Wire ran under the rubber around the door

    Then I poked the wire between the headliner and the top of the windshield.

    Wire ran under the headliner

    Fully wired unit

    Next I ran the wire for the remote mute button up behind the steering wheel and mounted the remote mute button where I could easily see it while driving, on the steering column, using black double sided foam tape.

    Wire ran to remote from behind steering wheel


    I mounted the remote just to the right of my tachometer. I can see it the moment it begins flashing, so even if I have my music turned up so that I can’t hear my device, I can see it working.

    And that’s that…. all done and ready to roll.

    Original Source

    Written by: Mol, Jun 29, 2009,

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