4 Way Flat Trailer Connector

Discussion in 'Lawn Mowing' started by River Hill, Apr 26, 2001.

  1. River Hill

    River Hill LawnSite Member
    Messages: 122

    I use a 4 way Flat Trailer Connector on my trailer. The left hand side has stopped blinking. All the wires and bulb look ok. I think the problem might be from my truck. Does anyone know what each of the 4 pins control. I took a test light to them and only 1 blinks with hazards on and only 1 shows a steady light???? I am lost. Maybe it is my trailer.
  2. Eric ELM

    Eric ELM Husband, Father, Friend, Angel
    Messages: 4,830

    1 is left turn signal, 1 is the right turn signal, 1 is the tail lights, and the last one is the ground.

    Sounds like it is in the truck wiring if it don't light up the tester.
  3. 75

    75 LawnSite Senior Member
    Messages: 992

    Brians - here's the standard colour code for trailer wiring:

    Green - right side turn/brake light
    Yellow - left side turn/brake light
    Brown - tail/side marker lights
    White - ground

    With hazards & parking lights on, your test light should show the following on the truck's plug: green & yellow pins should be flashing, brown pin should be a steady light. If this isn't the case, find & fix the problem on the truck's wiring first - and make sure that the white wire is connected to a good ground on the truck's frame or body.

    If the truck plug checks out OK, the problem is on the trailer. I don't know what style lights you have on your trailer (individual bulbs that twist into bases within the light assembly, or the sealed-beam type that the wiring harness plugs into the back of) but check the connections for corrosion buildup - this can prevent the circuit from being completed, even though the wiring is OK. If you have lights which take individual bulbs, double check the bulbs if all the wiring still seems OK - once in a while I have seen a bulb that looked alright at a glance but wasn't working.

    Hope this helps - good luck sourcing down the problem.
  4. earth works inc.

    earth works inc. LawnSite Member
    Messages: 42

    Brians, if the truck is not too old, go out and buy a complete kit to hook into your existing light system. If it still doesnot work, check the wires from the truck for corrosion, cut wires etc etc.

    Then once the plugs from your truck works, go to the trailer lights.

    You might pay a little more for the kits that are already wired, but they will work if the truck and trailer is right.
  5. River Hill

    River Hill LawnSite Member
    Messages: 122

    I just tested the truck and the yellow is the problem. I followed it all the way to where the long 4 way connector plugs into the circle receptacle on the truck. I tested there and still nothing on the yellow. I don't where to go from here. Maybe a fuse?????????????? I would buy one of those kits but the problem is even before where the kit plugs in. Any more suggestions? Thank you guys for your help.
  6. Eric ELM

    Eric ELM Husband, Father, Friend, Angel
    Messages: 4,830

    Does the left turn signal work on the truck?

    If so, run a wire from there to the plug.

    If not, keep tracing farther.
  7. River Hill

    River Hill LawnSite Member
    Messages: 122

    Thanks for the help guys. I will trace until I find the broken link. I will keep you guys updated.

  8. River Hill

    River Hill LawnSite Member
    Messages: 122

    I traced it back to a fuse in the power distribution box. On my F150 there are seperate fuses for the towing harness. Thanks again for your help. I guess I will be going Bass Fishing today after all. We have had great weather here in the Mid-Atlantic so I am all caught up, now if I can just get those Bass on my line.
  9. 75

    75 LawnSite Senior Member
    Messages: 992

    Brians - that's good news! Glad to hear you're "functional" again. Look out fish! :eek:

    Just wondering how well the flat 4-wire plugs hold up for you - if they work fine no reason to change. In my case, I have found that here in Ontario, they l-o-v-e to salt the roads so in spring, these connectors tend to turn green & crumbly. So I switched to a smaller version (mine is 6-pin, but they are also available in 4-pin) of the plug used on tractor/trailer hookups. They have a spring-loaded cover to keep the elements out. Also, I use a plug on the truck AND trailer, so whenever the trailer is parked there isn't a cord end hanging out in the open. Just gotta make sure the "pigtail" doesn't get misplaced...............

  10. dan deutekom

    dan deutekom LawnSite Senior Member
    Messages: 424

    Love that pigtail idea. I don't know how many times I have had to replace the plug because it got in the way when backing the truck up to the trailer and pinching it or it fell off the tongue and into the mud. Next time I need to fix it I will make one up like that. Still find that the salt gets into those fancy plugs during the winter.

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