5 wire flat prong trailer wires into a 4 wire

Discussion in 'OnBoard Electronics & Controls' started by Mark B, Oct 4, 2017.

  1. Mark B
    Joined: Sep 2017
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    Location: Ny

    Mark B Junior Member

    I have a 5 wires on 4 prong harness on my trailer and I have been trying to hook up to my dads truck and all the lights are and have been working incorrectly. We noticed today that his is a 4 wire set up. What do I do to make my lights run correctly. Any help would deff. Be appreciated. Thanks
     
  2. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    Flat 5 wire harnesses have the fifth connector for electric brakes. It shouldn't affect the lights if wired properly.
     
  3. Mark B
    Joined: Sep 2017
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    Location: Ny

    Mark B Junior Member

    I don't think its for brakes
     

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  4. Mark B
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    Mark B Junior Member

    There is five wires but just 4 prong connector
     
  5. Mark B
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    Mark B Junior Member

    Colors are yellow,yellow and brown,green , green and brown, then the white ground
     
  6. Mark B
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    Mark B Junior Member

    Anyone please help
     
  7. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    About 5 minutes with a tester or multimeter will sort his out.

    Typical arrangement:
    White-Ground
    Brown-Tail/Running Lights
    Green-Right Turn/Brake
    Yellow-Left Turn/Brake

    What you have is a split harness, sometimes called a wishbone style. It's a 4 pin (4-way), but where the wires come out of the running light circuit, is split so you do not have to run a jumper wire between tail lights.
     
  8. BertKu
    Joined: May 2009
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    Location: South Africa Little Brak River

    BertKu Senior Member

    The best way is to take a 12 Volt 10 watt globe/bulb/ whatever and use that together with a 7Ah battery to figure out what the connections are. I found often that the multi meter gives false leakage current reading and you can go babana's. With a globe you don't have that problem and you can see immediately what is what, as you first get what is what from your truck with the globe and then with a globe and battery on the trailer. Then walk then to the back of your trailer and see what is dim glowing, brake light, indicator light, left, right, normal light. Well , that works with non USA standards. Bert
     
  9. Mark B
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    Mark B Junior Member

    If I press brake,the lights on trailer go out and when I put a turn signal on both. Tail lights blink
     
  10. BertKu
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    Location: South Africa Little Brak River

    BertKu Senior Member

    Mark, you will go banana's, use a globe/bulb to figure out what comes out of the truck connection. Bert
     
  11. Mark B
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    Mark B Junior Member

    Ok Ty. Is there some sort of chart or something to tell me what the power reading should be and exactly what each reading should be and how to ck with bulb. Not to good with this wireing stuff
     
  12. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    The white wire is the ground for all the trailer lights. You either connect another wire and ground the lights, or connect it to the trailer frame and use the frame as the common ground.
     
  13. BertKu
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    Location: South Africa Little Brak River

    BertKu Senior Member

    OK I can only guide you with a non USA standard. The principle of finding out what is what is the same. You take a 12 Volt bulb/globe/lamp/light with 2 wires. You first switch in the truck the left indicator on. Then you connect one side of the lamp to a connection and then the other to the body of the truck, normally connected to minus. Nothing happening? you move to the next connection with the one wire, the other stays to the body of the truck. Nothing again, you go to the third connection. Still nothing? you go to the fourth connection, Yes, your lamp start flashing , because your indicator is on to the left. This is your left-hand indicator, you make a note on paper. Now you switch the right hand side indicator on, You move the one wire again from one connection to the other until it start flashing, that is your right-hand indicator. Make a note and then switch indicators off and switch your light on. When the lamp lights up, make a note, this is your lights. Now the 4th connection must be the brake light. Ask somebody to sit in the car and ask him or her to push on the brake pedal. If you lamp lights up, you have all 4 connections.

    Now you get a 12 Volt battery, put minus of the battery to the ground of the trailer and one side of the lamp/bulb/globe/light to the plus of the battery and the other you make contact to a connector point on the trailer. Ask somebody to shout at you when any of your lights light DIMLY up. Bingo, yes, you have one connection right. You make a note on paper. Dont try to be clever and think you can remember everything. Then you move to the next connection. etc. until you have all 4 of them. Now you have to connect the trailer connection to the 4 truck connection. It take 5 minutes in all, ANY OTHER WAY WILL TAKE YOU DAYS AND YOU WILL STILL NOT HAVE IT RIGHT. If you do it in any other way in 5 minutes, I will take my hat off for you, you are then a genius. Bert
     

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  14. BertKu
    Joined: May 2009
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    Location: South Africa Little Brak River

    BertKu Senior Member

    OK maybe the trailer minus or ground is not connected to the body of the trailer, in that case you keep the battery minus wire on according to GONZO onto the white wire. Then start moving with the other wire over the left over 4 connections. Your helper will tell you what is dimly light up. Brake lights, night lights, left indicator, right indicator. The rest is as per previous post. Bert
    P.S, you lamp/bulb/globe must be at least 12 Volt / 15 to 20 watt. i.e. 1,2 to 1,6 Ampere
     

  15. Ike
    Joined: Apr 2006
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    Location: Washington

    Ike Senior Member

    All te above is unnecessary. I ran into the same problem about 12 years ago when I bought a trailer to haul my car behind my motor home. The motor home has a five wire arrangement. The trailer a 4 wire. (I have since sold it) Anyway you can go to a trailer equipment store and get an adapter. I have one on my trailblazer because it is five wire and my boat trailer is four wire. You can get them that go either way, 4 to 5 or 5 to 4. And they aren't expensive. I think the one I currently have cost less than ten bucks. The most expensive one I have seen was around $40.00.
     
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