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Reverse light question

Discussion in 'Truck & Equipment Repair' started by ebski387, Dec 27, 2005.

  1. ebski387

    ebski387 Junior Member
    from ny
    Messages: 24

    ok ive been searching and doing alot of research and my heads spining cuz i still dont understand how to wire them. i have a 05 ram 2500 and want to mount 2 12volt lights for reverse light. i want to have a 3 way switch so that i can shut them off, keep them on all the time, or have them come on when the trucks reverse lights come on. i want to do it the right way so that it wont overload anything either
  2. Dogbonz

    Dogbonz Member
    Messages: 96

    sounds to me like you'll have to run 2 positive wires to your rev lights,,, i hope you are going to mount EXTRA lights and not try to do that to you stock rev lamps,,,any who,,, if you mount some fogs in back and wire them to a switch in your truck, then of coarse they'll be on when you want and if you also tap in to your factory rev lamps wiring, and run those to your fogs also,,then they will come on when you hit the lever in reverse or by the switch! hope that helps:salute:
  3. NEPSJay

    NEPSJay Senior Member
    Messages: 270

    i think u need a relay for that app.
  4. SnoFarmer

    SnoFarmer PlowSite Fanatic
    from N,E. MN
    Messages: 7,921

    A couple of relays and some diodes and a good three way switch, and some wire and your set. :waving:
  5. Dieselman19

    Dieselman19 Senior Member
    Messages: 141

    first you will need a hot wire to the switch, a ground to the switch, run a wire to the lights in the back to the switch, then just tap the reverse lights, you can do this by connecting the wire that went from the switch to the lights to the truck reverse wire. That should do it, if you do this and you blow the fues for the trucks reverse light you will need to add a relay in the mix, but i think you will be ok that way i described. With a relay you just run all of your wires throught the relay first before the switch, try the first way i said if it doesnt work then i can go more into detail about the relay i hope this helps
  6. rdtyphon

    rdtyphon Junior Member
    Messages: 2

    Reverse Lights

    Actually if you want to do it right. You will need to use a relay so not to overload any circuitry in the vehicle.

    If you are knowledgable on relays then you should have no problems.

    You will need to run a fused wire from the battery to the location of the relay
    from there you will need to connect that wire to pin 30 the comm on the relay. Next you will need to wire pin 85 to ground. Then pin 87 the N/O should be wired to the positive wire on the reverse lights. Now for the switch
    the comm pin should be wired to pin 86 on the relay. now the 2 remaining terminals on the switch one needs to go to 12 volts and the other to the positive reverse wire on the vehicle ( This wire can be found at several locations in the vehicle. Ignition harness and Driver or Passenger Kick Panels are the most common). Now the gauge power wire that needs to be run to the lights will depend upon amp draw of the lights. Hope this helps
    This will acomplish your goal of having a OFF, ON, or ON with Reverse.
  7. Mdirrigation

    Mdirrigation Senior Member
    Messages: 408

    And you should mount a warning light in the cab of the truck so you know that the lights are still on . Nothing worse than riding behind a vehicle looking at reverse lights
  8. basher

    basher PlowSite Fanatic
    from 19707
    Messages: 8,990

    You can pick a thirty amp 12v supply line to power the relay from the trailer tow package in the rear. Plus add a diode between the relay and the truck, todays vehicles are sensitive to changes, so many computers. Use a lit switch so you can tell when the lights are on.
  9. norrod

    norrod Senior Member
    Messages: 113

  10. Detroitdan

    Detroitdan PlowSite.com Addict
    Messages: 1,937

    wow, you guys get technical! I have done this a few times with only a three position switch (on-off-on). Only times I've ever used relays I had problems, stupid things only work for a few months then fail. All you need is an inline fuse on each hot side, unless you plan on leaving the lights on forever. Even with auxiliary backup lights, it's generally a momentary function. Put battery power to one side, backup light power to other side, wire to backup lights in the middle. Piece of cake. Just use a good heavy duty switch, it will get hot if you leave it on too long.
    I was going to do this in the truck I have now, but I so rarely need it I haven't bothered. A couple times hooking up a trailer at night I shut it off in reverse, left the key on and set the brake good and hard. works good enough for the 2 minutes it takes me to hook or unhook. Course, my new camper has a nice light mounted on the front of it just for that purpose, so I don't even need reverse light trick anymore. Another option would be a cheap set of clear fog lights, 15-20 bucks at Wal Mart or parts store, comes with a switch, too. Just hook them up alone for rear work lights.
  11. ebski387

    ebski387 Junior Member
    from ny
    Messages: 24

    thank you so much for everyones help i just have one more question where do i get the feed from the reverse lights my truck has a 4 prong under the bumper and a 7 prong in the bumper

    CARDOCTOR PlowSite.com Addict
    Messages: 1,304

    white wire -green tracer picked up mine underhood .drivers side near fire wall
    dont for get relay

  13. Ian

    Ian Member
    Messages: 96

    The reverse light wire is one of the wires in the 7 pin RV plug that your truck has.

    One of the wires in the 7 pin plug will be a hot wire to the trailer. It is hot all the time or at least with the key turned on. Start the truck and put into reverse. Set the parking brake and turn off truck will still in reverse. The back up lights should stay on. You might have to leave the key in the on position. Use a meter or simple wire and light to find the powered wire. There will be two of them, one for the reverse and the other for the hot wire to the trailer. Splice into it behind the trailer connector.

    Or, you could buy another 7 pin trailer side connector and run the hot and ground wire to the new connector and simply plug the new back up light into the trucks 7 pin RV connector, but then you wouldn't have the feature of turning on the light independantly of the reverse lights.
  14. justme-

    justme- 2000 Club Member
    Messages: 2,138

    That's probabily caused by the wrong relay chosen or the mounting location of it. Use a relay- 2 rubber utility lights draw 70Watts:W=V*I (I = amps, V=volts, W=Watts.) so 70/12= 6 amps. Sounds small enough, but it really isn't, especially adding the resistance of the wire for the length of the truck. You also don't really want a 6 amp circuit running through the dash- fire waiting to happen.

    Incidentaly- 14 guage wire is BARELY adaquate for that current (5.9amps max) so use 12 guage to feed the lights.

    Oh, and driving with reverse lights on can be a finable offense too- definatly use a lighted switch in plain view or a warning light in the dash.