Electric trailer brakes, plug 'em in, they lock up....

[Soundguy]

Ditto what Diamond said. there are 2 different ways the brakes can be wired. i have 6pin plugs on my trailers and 7pin plug ont he truck.. when buying, for instance, a hop 7to6 pin adapter.. there is a wire inside that has to be swapepd.. hop knows this, and while all the other wires inside are soldered.. 2 are screw terminals for reversing.

soundguy

There are two ways manufactures wire trailer brakes. They swap two pins. I run into this all the time due to towing over 100 different trailer each year. There are only two ways to wire them as a standard. My suggestion is to look the plug on the other trailer and match it to the old trailer that works. GM trucks will also lock up some trailers with no controller installed in the truck.


Here is a good site to help
Marksrv.com 7 way wiring diagram page
Chris

 

[montejw]

FIXED! Opened up the adapter and swapped the wires that go to pins 2 and 4 of the 7 way and all is good. One of them is the center wire on the 6 way. I read a little more elsewhere and it seems the difference is in the 6 way plug itself, a couple ways it's done on those and the 7 way doesn't always match.

Thanks all for the help. My wife is happy and amazed I found the fix so quickly. I said "sheesh honey, it's the internet, what'd you expect?"

 

[montejw]

He is right about swapping the adapter. So what you are saying is you have a 7 pin on the truck and a 6 pin on the trailer. You are using a adapter between the two????


Chris

Yes, the trailer has a 6 way molded onto the wire, the truck has a 7 way recepticle, so there's a 6 to 7 adapter. I swapped the wires inside the adapter that go to pins 2 and 4 of the 7 way end.

 

[Diamondpilot]

Good, glad we got you pointed in the right direction to get it fixed. Like I said I run into this from time to time in my marine business. I bet I tow 100 or more trailers each year. I just started cutting off the ends and putting the 7 pin on everything. I buy them 24 at a time and they only cost me $4 each. You can get them at WalMart for about $8 or so. A lot of what I am doing now requires 5 wires on a trailer even with out electric brakes for backup light signal. It uses that signal to activate a electric cut out in the hydraulic surge type trailer brakes.

Chris

 

[montejw]

I just started cutting off the ends and putting the 7 pin on everything....

Thanks for the quick help. I'll most likely remove the molded 6 way plug and adapter, and install a 7 way plug eventually. I bought one thinking I would have to do that last night, but swapping the wire in the adapter got it going, good enough for now.

 

[montejw]

Sounds like the trailer brakes are doing what they are suppose to.
Your not suppose to have voltage on the truck side when the brakes are not applied.

There is voltage there, it must be very low amperage, probably the controller circuitry doing something to make sure there are brakes on the other end of the wires. When we first hooked up the new trailer the controller indicator wouldn't light up, even though it was connected to the interior lights of the trailer. After swapping the adapter wires the controller indicator lit up and it all worked.

 

[Soundguy]

Glad you found it.

soundguy