Is there a diagram anywhere of what each of the pins on the trailer plug are for? Basically I'm trying to find out if it has a pin for backup lights as my small trailer has a 5 pin flat plug that includes a wire for reverse lights.

 

have a look here.

 

The Rams have a 7 pin connector? Awesome, backup lights should be not a problem then...

for the record I don't yet have my truck, which is why I was unsure if it was a 7 pin or something else.

 

ok, here's where I'm curious now: If I bought a 7-5 pin adapter, what would the 5th pin be used for?

My trailer was previously towed by my minivan and I wired up the harness so it would include the 5th pin for reverse lights on my trailer. I can't exactly re-wire an adapter so I'm not really sure what would happen if I plug my 5 pin trailer plug into an adapter on the truck......would I still get reverse lights, or would that 5th pin be used for a brake or some kind of aux power?

 

On a lot of 'em, the fifth pin (backup lights) is used to close a solenoid, to prevent fluid flow to the rear brakes when you are trying to back up. Of course, this assumes that your trailer has surge brakes on it....... If you don't, and actually have backup lamps, I would guess it would be for those.

 

no brakes on my trailer, it's only a 6x4, not very big. I just stuck some LED fixtures on it so when I'm backing it up at night on my dark property it lights everything up nicely.
I was also thinking a similar thing about the braking pin since it would only be active in reverse anyway, and as long as it's 12V it should work just fine.