1. Welcome to PlowSite. Notice a fresh look and new features? It’s now easier to share photos and videos, find popular topics fast, and enjoy expanded user profiles. If you have any questions, click HELP at the top or bottom of any page, or send an email to help@plowsite.com. We welcome your feedback.

    Dismiss Notice

Relay part number?

Discussion in 'Strobe Lighting' started by justgeorge, Dec 1, 2011.

  1. justgeorge

    justgeorge Senior Member
    Messages: 223

    OK I've searched thru lots of threads on here and people mention installing a relay but I'm a bit of a dummy. I can't find any thread where someone specifies a relay to order.

    I want to install my LED backup lights on a relay and a on-off-on switch so I can turn them on, off, or on-in-reverse. I did find a on-off-on switch at the auto parts store. What is a relay I can order online or at a normal auto parts store (Pep Boys, OReillys, Autozone is what i have near me).

    Also, for a dummy, what wires run where? My LEDs have a black and red wire coming out, I've temporarily wired them via a 7-pin round jack into my trailer hitch jack. Is it battery to switch to relay to lights?

    No matter how simple you explain it you won't offend me..... :help:


    RBRONKEMA GHTFD 2000 Club Member
    Messages: 2,592

    Any ole relay from any auto parts store will work I would assume. I have never done a wire up like that before surprisingly. Google can be your friend if you can't find what you are looking for. Also Ask Dissocative (His name is George.) He has wired up many of what you would like to do, and knows it like the back of his hand.
  3. s&mll

    s&mll Senior Member
    from NJ
    Messages: 260

    Made this for you real quick.

    Sorry its sloppy but i made it in paint.

    Just get a 4 pin relay You can just a 5 pin just look at the relay and wire it so it switchs closed when u feed the pin 12volts.

    I normally go in autozone and just pluck a relay off the shelf. They are in the backroom not in the isles. Your only switching under 10amps so dont worry about getting a 40 amp or anything expensive

  4. basher

    basher PlowSite Fanatic
    from 19707
    Messages: 8,990

    If you are going to wire them to the reverse lights you need to throw a diode to protect from back feeding when you turn the switch on.
  5. justgeorge

    justgeorge Senior Member
    Messages: 223

    Great picture, thanks. So the wire from the switch to 12V reverse can go to the reverse post on my trailer hitch plug or the reverse wire going to the lights? And the wire going to "12V ignition" can be tied into the same wire I use for my plow and spreader control that is hot when the ignition is on?

    And for Basher, the diode is a Radio Shack item? Where would it go in the diagram?

    Also, what gauge wire, 16?
  6. s&mll

    s&mll Senior Member
    from NJ
    Messages: 260

    Wire the diode in on the reverse light line..... I never use diodes but i also install on my own trucks not customers. Better to be safe then sorry. Plus a diode should be 3 dollars or so.

    I go stright from the fusebox. http://www.onfair.com/add-a-fuse-ci...-holder-tap/?gclid=CIbmxIvv5KwCFUx_5Qod4guANg

    And use that on the trailer b/u lights. They are only rated for 10 amps so I dont use the trucks reverse circuit since its 20amps.

    I use 14gauge for power and 16gauge for ign and reverse wires.They carry a very small load since all they do is tell the relay to flip on.
  7. justgeorge

    justgeorge Senior Member
    Messages: 223

    Well after many hours, several trips to various stores, lots of money (wire isn't cheap), I got it all wired up today. Fired up the truck, tested it, and so far what I accomplished was that now my truck reverse lights are on ALL the time, no matter what position the switch is in, and the aux lights won't come on at all. :realmad:

    Tomorrow I'll pull the wires back from the engine compartment to the back and see where I've mis-connected something. I put all the wires in 3/8" split loom housing so it's impossible to track an individual wire front to back. :mad:
  8. oldmankent

    oldmankent PlowSite.com Addict
    Messages: 1,317

    You'll get it.
  9. s&mll

    s&mll Senior Member
    from NJ
    Messages: 260

    If you follow my picture you should have no problem.
  10. s&mll

    s&mll Senior Member
    from NJ
    Messages: 260

    You must of hooked into trucks reverse lights not the fuse underhood.When doing this you must use diode as you are back feeding ign wires to lights. look at bashers post
  11. haf728

    haf728 Junior Member
    from sw mich
    Messages: 7

    Do you need a relay?

    LED light do not draw the amps that halogen bulbs do.

    correct me if I'm wrong but i think a DPDT heavy duty On-Off-On switch would work.
    If you wired it like this pic

    Rev.12v+ to #2
    12v+ to #5
    Aux.light on #3 and #4

    switch up (on with rev lights)
    switch middle (off)
    switch down (on with ignition)

    When switch is up #2 feeds #3 (at the same time #5 feeds #6 hooked to nothing and can't back feed thru #4 it's open)
    When switch is down #5 feeds #4 (at the same time #2 Feeds #1 hooked to nothing and can't back feed thru #3 it's open)

    Attached Files:

    • 3way.bmp
      File size:
      622.3 KB
  12. justgeorge

    justgeorge Senior Member
    Messages: 223

    I did hook into the truck reverse light for the wire into switch position #1. I used an "add-a-fuse" for the connection into switch position #3.

    I'll get the diode, but that wouldn't cause my problem of the truck reverse lights all the time. Looking at the picture again if I managed to screw up a wire and took the reverse 12V+ into switch position 2 instead of 1 could that do it?

    Also on the relay I bought the numbers aren't in the same order as in your picture, 87 and 85 were reversed from your picture. I'm amazed that those aren't standardized.

    Probably I just have a wire plugged into the wrong slot either on the relay or the switch, pulling the bundle back will let me do a continuity test from one end to the other and then I'll label them better.

    Thanks guys!
  13. justgeorge

    justgeorge Senior Member
    Messages: 223

    Well I'm partway there, the problem with the truck reverse lights being on all the time is solved. Now I get the aux lights on when the switch is in the #3 position and the truck is in reverse, I would have expected the aux lights to be always on when the switch is on #3.

    When the switch is in the #1 position the aux lights don't come on at all, in reverse or not.

    Off to Radio Shack to get a diode.

    Edited to add - I mistook what you referring to with the add-a-fuse. I think what you were telling me was to use the add-a-fuse in the fuse slot for the trailer b/u lights fuse and that's the wire that should go into switch position #1? I'm not sure what fuse slot I even used other than it was a 10 amp. That's probably my problem.
    Last edited: Dec 9, 2011
  14. justgeorge

    justgeorge Senior Member
    Messages: 223

    Final update. That was my problem. I had the add-a-fuse in fuse slot 1 which was trailer right turn, so since I didn't have the turn signal on nothing worked. I moved the add-a-fuse to the trailer backup fuse slot and quit using the wire where I tapped into the reverse lights. Then for the 12V+ wire I used the same connection as I use for my plow control.

    My other confusion was in how the switch itself works - when in the UP position I expected to get switch wire 1 active, but instead it activates switch position 3. Told you I was a dummy.... :confused:

    Anyway, it's all working, thanks again!
  15. Dissociative

    Dissociative 2000 Club Member
    Messages: 2,066

    Why aren't any of you using my TRIPLE SWITCH MOD...

    use a DPDT and you can have it work 3 ways...not 2

    up= force the lights on
    center = total dark....(for being sneaky)
    down = reverse triggered....

    i like the ability to dark out the truck....leaving a bar late...backing into a customers drive by their window at night....ect.ect.

    EMAIL ME for a diagram....
  16. s&mll

    s&mll Senior Member
    from NJ
    Messages: 260

    That is the way i my diagram showed him how to wire it. Now that he fixed his wires and followed my diagram it works.
  17. joshg

    joshg Senior Member
    from VT
    Messages: 141