Trailer question
 

I just went to hook the new boat up and take it down to the marina, when i went to plug the lights in i noticed that the harness was a five pin harness, one femal four male. and the harness on my truck was a standard four pin like every other trailer i have owned, so my question is, does anyone know why it has the extra pin and is there an adaptor for this.
thanks in advance
Jason

I have the same on my trailer. Don't know what the extra pin is for except maybe a brake. I still use the flat four and it works fine.

Answer
 

hey if your trailer has brakes then that extra plug is for the brakes. if your trailer has mechanical then that is so the brakes dont lock up when you back up. it gets hooked up to you to your back up lights and prevents the brakes from engaging. any questions let me know.

Like VelocityMike said , If you have eletric brakes the extra wire powers them . If you have serge brakes it hooks to back up lights and keeps brakes from aplying while backing . You should be able to get an adapter .

Thanks for the replies everyone. This would explain why i had to get out and move a switch on the coupler before I could back up, my brakes are mechanical, noe, does anyone know how i would wire this extra wire? my truck has the seven pin round connecter but i think it only has the four wires hooked up. does that make any sense?

thanks again
jason

On the coupler there should be a wire that can be hooked into the connector so that when you shift into reverse it powers the brake open.
Mark

I run the seven pin setup, and I always wire the backup lights to the center pin.

Cool tip-The 5 pin plugs into the 4 pin and there is one extra prong not plugged into anything. On some trailers, this extra plug releases the brake when there is power applied to it so you can back up.
While jambed in at a busy gas station on a busy saturday because I couldn,t back up, I put my forehaed into my hands and thought"what am I going to do, I can't back up because my brakes won't release in reverse,I look like retard sitting here,boat and truck are very spectacular looking and 5x as big as any vehicles here,I look like a retard,I look like a retard!"
I knew I needed to get power to that extra prong somehow but didn't have any wire or anything.
Solution-unplug 5 pin trailer plug, turn the plug upside down and plug it back in.Get in truck and turn lights ON as this gives power to the extra prong that is now plugged in.Now you can back up!Don't forget to plug back in correctly or your signal lights may not work.
Yeah, yeah,I know a lot of you may have already known this but I I thought of it under intense,almost embarassing pressure!note-my trailer doesn't have a manual release on it
I since have had a round to 5 pin adapter made at the hitch shop.($10)