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  • wiring up some reverse lights

    I installed some auxilliary lights on the back of my tj...right now they're hooked up to a switch, but I know theres a way to make them turn on when put it in reverse OR when I flip the switch....does anyone know how I would do this?

  • #2
    how do you plan on getting power unless the switch in the tranny or the mannual switch isn't on...... image it like water you can't flow water thur a pipe unless the valve is open to let to flow thur . so if either switch is close'd no power to lights . so your going to need to lay them hook'd mannual switch or hook into the rev's wire on the harness which can easy done with either test light or meter


    • #3
      You will need to go purchase a relay from your favorite auto part store
      Heres a diagram:
      the red pluses are to the positive terminal on the battery
      The green wire goes to the positive wire to the reverse light inside the rear tailight
      The purple wire goes to ther positive on the new light you want to add

      You will just put two wires onto the one that goes into the rear from the switch and one from the relay.

      the reason for the relay is so you will have enough power to light up the lights while using the rear tailight as a switch.

      Good luck


      • #4
        Ok. As far as gauge goes.

        Use 16 for... all grounds (negatives - the switch if it has one, the relay, the auxillary lights), from the battery to the switch, from the switch to the relay.

        Use 10 or 12 (10 would be better since it's a longer way to the back of your Jeep) for connecting... the battery to the relay, the relay to the lights.

        The schematic that Ryan listed above is different from my configuration.

        I use my rear lights independently from reversing and, as such, have a separate switch to turn them on and off. As I have it:

        1) There should be two wires leaving the positive terminal of the battery. A 16 gauge to the switch (to power the switch), and a 10 gauge to the relay (to provide an "in source" of power).

        2) There should be another 16 gauge from the switch back to the relay (to the "switch" prong on the relay).

        3) There should be a 10 gauge from the relay to the lights (coming from the "out source" prong on the relay).

        The reason for the relay is to not overload/burnout the switch and/or draw too much power through the wires and the potential electrical fire that comes along with it.

        An in-line fuse may be overkill, but I have one, cause you never know - and - in my humble opinion, the best electrical fire is the one that never starts.

        Good luck.


        • #5
          Originally posted by sgana
          Use 16 for... all grounds (negatives - the switch if it has one, the relay, the auxillary lights), from the battery to the switch, from the switch to the relay.

          Use 10 or 12 (10 would be better since it's a longer way to the back of your Jeep) for connecting... the battery to the relay, the relay to the lights.
          this makes no sense, use same guage on all wires, your only using as much current as you can ground.

          using 12 ga with a 16ga ground is just like using 16ga all the way around. depending on what kinds of lengths he is running (almost a negligable distance in any swb jeep, unless wired in a maze) this restriction gets greater over a longer length....yes for short distances its not really gonna make that big of a difference, but from the battery all the way to the back, you may over heat that wire.


          • #6
            Actually, thejeepingoat, you are correct. Using 10 or 12 gauge all the way around can be done, but that just pulls way harder on your battery.

            I wouldn't use 16 gauge to go to the back, it is too far a distance and the draw/heat would be too high in the risk zone for my liking - definitely if the auxillary lights are 55w or above. It's been a while, but when I wired mine, I believe I used about 15 feet of wire to get around all the bends and twists to make it look like a neat job.

            Using 16 gauge for the grounds just gives a place for the current to escape to. There is no power draw on the ground wires. Using 16 gauge for the switch and back to the relay is what one should use. That is the purpose of the relay. The power draw on the switch is much, much less; it circumvents the necessity of having 12V running through the switch. The relay itself only needs a little power to make the internal connection to allow the full 12V flow from the battery through the relay to the auxillary lights. Again, that is what a relay is for.

            Some cheaper manufacturers just throw an in-line fuse to connect their product: from the battery-to the switch-to the lights hoping that the in-line fuse will burnout before any other place. It works, but I don't think that is the safest thing.

            But then again, being paranoid and cautious and safe is my nature.
            Last edited by sgana; 08-03-2005, 07:51 AM.


            • #7
              Good diagram.

              One thing I saw that I would do different, is not to run a line from the battery to the switch, but from either the unswitched or switched auxillary wires located behind your glovebox. There is no need to run a line all the way to the battery, when these two wires are here just for this particular purpose (to power low power accessories, like switches that lead to relays).

              So then all you have to do is get a relay from Radio Shack, connect both the switch, and the line for the stock back up lights, to the "switch" terminal of the relay. The connect the power to the battery, plug in the the lights, and the ground wire, and you're set to go. Good luck.


              • #8
                Just 2 cents but
                When I ran mine in the back I switched between no lights and with the backups from the taail lights and then added a 3rd position switch so I can run them with out being in reverse.
                The reson was I don't want to wake up the whole camp just because I want to go for a drive. Like I said 2 cents
                oh ya as for wire gauge use the same on both sides. and fuse it