View Full Version : 6 PIN Trailer-7 PIN Tow Vehicle-- HELP Wiring

04-01-2009, 02:24 PM
I purchased a new truck that came with a 7-pin round male setup, but my trailer is a six pin round female, as well as several other of my vehicles. They new truck is a 1997 ford F350XL with a 351 W. My trailer has an electric brake. I bought a new 6 pin male setup for my truck and wired it as follows:
Yellow Wire- Left Turn Signal (LT)
Green Wire _ Right Turn Signal(RT)
White- Ground(GD)
Brown- Taillights(TM)
All of these work fine, but this is where I am running into a problem: I cannot get the brake lights or electric brake on the trailer to work, and now the brake lights are not working on the truck either. I have three wires remaining: RED-BLACK -BLUE. But only two terminals on the new plug. one reads: (A) and the other is (S).
I have tried every different combination, but no avail. I believe the middle terminal labeled (A) is auxiliary, when I plugged the blue wire in to that the brake lights on both the truck and trailer stayed on with out the brake peddle depressed.
I also tried splicing the RED and BLUE together in the (S) terminal, which is the brake but that didn't work either.

The truck is equipped with a electric brake controller that appears to work fine.
Anyone know how to fix this problem?

04-01-2009, 03:15 PM
Check your fuses

This link might help too


04-01-2009, 03:21 PM
Fuses are good. I checked that site too but still nothing.

Horsepower Lawns
04-01-2009, 07:08 PM
A (center) is auxiliary - Hot
S (outer) is brake
That is on most trailers. Some of the trailers have A (center) as brake & S (outer) as Hot.

On the Ford
Blue is brake
Red is Hot (only if the key is on, unless you put in a jumper)
I don't think Black is a color on Ford, is it Black/green stripe thats Backup, not used on a 6 pole.

Now the bad news, if you put the Blue & Red together and the Red was powered up, that can cook the controler.

We make a lot of $$$ at my 8-5 job from people doing stuff like this.:p

If your lights stopped working you popped a fuse, not sure off the top of my head what its marked, but sometimes there are 2-3 fuses that have something to do with brake lights & you will need your book because Ford doesn't mark the fuse box lids.:dizzy: