Trailer wiring help

[Robert F.]

Hi Folks,
I have just bought an equipment trailer and am trying to get all the electricals to function. It is a 2006 Hudson trailer with what appears to be good wiring. The former owner said that everything worked fine. It has a 6 prong plug. My towing vehicle is a 2003 GMC 1500 with towing package and a 7 blade RV type plug. I bought an adapter to convert from the 6 to the 7. Everything seems to work fine as far as lights are concerned. When I plug in the trailer, the brake controller tells me that the trailer is disconnected. All functions work on the truck end except the contact on the truck plug that is for battery does not light my test light. When would this contact have power to it? Should it be live all the time or only at certain times? I have not tried the brakes yet since the brake controller gives me this error message. Thanks in advance for any help.
Bob

 

[joecdeere]

Robert, I don't know if this applies here but on most adapters being sold now, the Battery hot and the electric brake wires are made where you can swap the two wire placements. I know when I bought a new 7 to 6 adapter last summer, the brakes would lock as soon as you plugged it in until I took it apart and swapped their locations. In mine these were the only two wires that were not hard wired and were made to swap. Maybe this will help.

 

[Couple of Achers]

Check out this website:
Trailer Wiring Diagrams

Some trailer manufactures use the center terminal for the brake circuit instead of one of the outer terminals.

Quote from their website.

*Sometimes the 12V and electric brake wire is switched

Take the plug apart on the trailer and move the blue wire from the center terminal to the proper outer terminal and try it. Also, not all 7 plug recepticals on the tow vehicle have the 12 volt wire hooked up. It is sometimes called a charge wire so you can charge your camper batteries while on the road. It also may be switched with the ignition, but I doubt that.

 

[Diamondpilot]

Robert, I don't know if this applies here but on most adapters being sold now, the Battery hot and the electric brake wires are made where you can swap the two wire placements. I know when I bought a new 7 to 6 adapter last summer, the brakes would lock as soon as you plugged it in until I took it apart and swapped their locations. In mine these were the only two wires that were not hard wired and were made to swap. Maybe this will help.

He hit the nail on the head. For some reason that makes no sense to anyone they wired the 6 way plugs 2 ways. You will need to swap the 12volt and brake wire. The converter you bought should have directions to show you how. If not take it apart. Most have all the wires soldered but 2 that are under screws. Just swap them.


Chris

 

[jwstewar]

Hi Folks,
I have just bought an equipment trailer and am trying to get all the electricals to function. It is a 2006 Hudson trailer with what appears to be good wiring. The former owner said that everything worked fine. It has a 6 prong plug. My towing vehicle is a 2003 GMC 1500 with towing package and a 7 blade RV type plug. I bought an adapter to convert from the 6 to the 7. Everything seems to work fine as far as lights are concerned. When I plug in the trailer, the brake controller tells me that the trailer is disconnected. All functions work on the truck end except the contact on the truck plug that is for battery does not light my test light. When would this contact have power to it? Should it be live all the time or only at certain times? I have not tried the brakes yet since the brake controller gives me this error message. Thanks in advance for any help.
Bob

You may also have to add a fuse in slot 1 of the fuse box under the hood. Most GM vehicles don't include a fuse in this location. This will charge the breakaway battery while you are towing. Chances are once this fuse is installed if you haven't changed how your adapter is wired, you brakes will be locked on your trailer.

Just a side note. I bought a stock trailer back in the summer. It had the 6 pin connector. I took 2 different 7-6 adapters with me to bring it home. I had power to/from the adapter but no trailer lights. He plug his truck in to the trailer. Lights worked fine. I pulled it home w/o lights. Swapped the 6-pin to the 7-pin RV and have been fine since. I had those adapters.

 

[QRTRHRS]

Do a search on trailer wiring. There are plenty of schematics free on line. If the above suggestions do not help, you might need to debug the trailer to see how it is wired.