Reverse lights on with trailer plugged in?

[superfish2]

Ok i have another question for you guys. I plug in my trailer lights and the back up lights on my truck turn on. I rewired the trailer last year it has been a constant since then. The truck can be off and parked and they will always be on as long as the trailer is plugged in.

[Jeremy airjer W]

Year make model of the vehicle?

What type of plug do you have on the truck 7, 5, 4 pin?

Are you using an adapter 7 pin to a 4 pin?

I'll make a wild guess and say that you have a 7 pin trailer connector on the truck and somehow the adapter or the trailer is causing power to back feed to the center pin which is the reverse power for trailer brakes. Once there is power there the reverse lights will come on.

[Macgyver55]

 Originally Posted By: airjer

Are you using an adapter 7 pin to a 4 pin?

I'm thinking he probably is, since a vehicle 4 pin has no physical connection to the backup light circuit that I know of. In any case, there must somehow be a completed circuit from the (black) 12volt (battery charge circuit) and the (yellow) backup light circuit. Could just be a loose wire in his connector, a bent tab, or a bad adapter connector.

[superfish2]

It is a 7 pin with an adapter. Last year I rewired the trailer lights after blowing a fuse in both my brothers truck and mine. I figured I'd start fresh with a whole new set up. I'll have to try a new 7 - 4 adapter and see what happens.