Tandem Axle Trailer Wiring

[torrin]

I have a 21ft Dorsey tandem axle trailer w/ brakes that has all of it's lights messed up. I say this because when I hook it up, the lights short out when i brake, when i signal one direction, all the lights seem to flash (even the running lights). And the running/tail lights are the only things that kinda work properly, thats until i signal, then they all flash.

So i disconnected the lights and cut the 7 way plug off the trailer, and found 5 wires only: (shouldn't there be at least 6 plus a seventh for brakes and a battery?)

Green
Yellow
Green/Brown
Yellow/Brown
White

And on my truck I have:

Green
Yellow
Brown
White


I know the wiring of my truck is fine because it works great on all 4 of my trailers that i own. Does this seem strange that there is only 5 wires coming from a Tandem axle trailer w/ brakes? And if this is common, how could I by-pass the brakes? (they need to be fixed to be hooked up anyways and the boat+trailer weight isn't too much for my truck t handle) and could i wire the trailer to a 4-way or would I have to go back to a 7 way round?

 

[dwco5051]

Re: Tandem Axle Trailer Wiring

Bad ground !!!

 

[NYBo]

Re: Tandem Axle Trailer Wiring

You only need 5 wires:
White = ground
Brown = tail and running lights
Green = right turn signal/brake light
Yellow = left turn signal/brake light
Purple = reverse lock-out solenoid (hooked to backup light circuit on tow vehicle side)

If you have electric brakes, you would substitute a blue wire for the electric brake controller for the purple wire in the above.

 

[oldjeep]

Re: Tandem Axle Trailer Wiring

 

[KD4UPL]

Re: Tandem Axle Trailer Wiring

You shouldn't have cut the plug off so hastily. It's probably just a bad connection on the ground. Plug the plug in and out several times, spray a little electrical contact cleaner in there if you have any. Unless your trailer is very unusual it doesn't have electric brakes. They will be surge brakes that are hydraulic in nature.

 

[Jetwash]

Re: Tandem Axle Trailer Wiring

Sounds like you can chase a lot of problems down or get a wire kit or a spool in every color. Use good nylon connectors with heat shrink and crimp. Some offer a solder inside as well.

 

[torrin]

Re: Tandem Axle Trailer Wiring

yup, there was the broken ground underneath the trailer, checked it and she was broken right off. If you don't have a solid ground on your trailer, the current going through the wires will more than likely bleed into any wire that is close enough to it (i.e you signal line and your taillights wire running through the same side of your frame in your trailer) and this will screw up all your lights, more often than not it has nothing to do with your wiring. Thanks for the inputs guys, just forgot about that stupid ground, I have one on my truck and checked that first and it's still attached so never checked the trailer's ground, ahhh durrr!

 

[NYBo]

Re: Tandem Axle Trailer Wiring

yup, there was the broken ground underneath the trailer, checked it and she was broken right off. If you don't have a solid ground on your trailer, the current going through the wires will more than likely bleed into any wire that is close enough to it (i.e you signal line and your taillights wire running through the same side of your frame in your trailer) and this will screw up all your lights, more often than not it has nothing to do with your wiring.

Not exactly. What happens is that you get an intermittent and/or poor ground through the coupler and hitch.