Hello all

I apologize if this question has been asked before... I did search through the archives, a bit, but didn't find what I was looking for.

So...
I've got a 2004 3500 that I've had for about 1½ years (we bought it used).
The truck already had a "towing" package on it... it came with the pigtail for a brake controller and a 7-prong RV style light connector in the bumper.
I've also got a 16' stock trailer with electric brakes. The light/brake connector on the trailer is the 'smaller' 6-prong connector.
I bought an adapter that fits in the 7-prong plug, on the truck, and the 6-prong cable from the trailer plugs in... and the lights work great, but... the trailer brakes are locked.

I've installed a brake controller (which I needed any way) but... the adapter still causes the trailer brakes to lock.

Where do I go from here? Can I make this adapter work? Should I rewire the connector for the 6-prong plug? (this would actually be preferable, since I don't own anything that uses the 7-prong connector) or... should I add in a 6-prong connector?

If either of the last 2 options are recommended... how/where do I wire things in? Can I splice into the harness behind the rear bumper, or do I need to run new cable back from the fuse box? I'd also probably need a wiring diagram...

Thanks for your time...


Steve

SGT USMC
1986-1996
2861/8511

 

the only difference between 6 and 7 is a constant 12v on the 7 prong, say for interior lighting. you could change the truck end to a 6 prong and just leave the 12v constant out. or if it were my trailer i would put a 7 prong harness on the trailer and just seal off the extra prong.

 

I had this problem with a trailer one time. With your foot off the brake the trailer brakes were locked, and when your foot was on the brake, the trailer brakes were unlocked. So I asked around and they said that the company (WW trailers) wired their stuff a little different. With a test light you should be able to figure out which pins on your truck are what and you can go from there. Not sure if you got the same problem as I did but may be something to look at. Hope this helps!

 

because you're a marine, i'll type slow.
on the 7pin connector, it's labeled what each pin is for....you should be able to either move the wires on the rear of the 7pin to where they need to go on your 6/7 adapter....or, as stated before, just put a 7pin connector on the trailer. it sounds as though the constant 12v is swapped w/ the brake wire causing the brakes to fully engage.
if it were me, i'd try and figure out what each of the 6 wires were on the trailer, and splice on a 7pin connector to the trailer wires. that way the truck is the way is should be....just in case it's ever used to pull any other trailer

 

I had the same problem. One adapter worked and the other did what yours is doing. I got sick of fooling with it and put 7 pin adapters on all my trailers.

 

There are two adapters for what you're talking about. You just got the wrong one. This is true, I've gone through the same thing. Go to whatever auto parts store you bought it from and check with them.

 

This is why I hate adapters.

 

What kind of controller do you have? Are you sure it's not ajusted to the max braking for the trailer? I had a problem with a controller being adjusted to tight and the trailer brakes locked every time I touched them.

 

OUCH !!!!


Here ya go. Hope this helps :

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[IMG]local://upfiles/42139/3D24EC9286764CF28FFDAB6A0FCA5E28.jpg[/IMG]

[IMG]local://upfiles/42139/B25367C9C4BF49A6AC8530A5400611F6.gif[/IMG]

[IMG]local://upfiles/42139/7B636B441F1F454B84136F69C99FFD1B.gif[/IMG]

 

Thanks fellas...

I really appreciate y'all typing slow...

I'm going to give it a shot. I'll probably try rewiring my adapter.

Most of the diagrams that I'm seeing are for a different 7-pin connector, though. The connector on my truck is a larger (about 1½" diameter) and has 7 flat pins in a circle with an empty hole (no connector) in the middle... not that that matters any, but...

Letme see what I can do about rewiring my connector...

Steve

SGT USMC
1986-1996
2861/8511