Guys, I have a 04 Silverado... Im using the 4pin adpater to hook into the 7pin one thats on the truck. All the lights on the trailer work fine. Except for when I turn on the headlights and hit the brakes. Then the just cut off? All the signals work fine, brakes fine, parking lights fine, but when I hit the brakes with the headlights or parking light on they cut off

any ideas? I couldnt get a good ground on the trailer so I grounded to the truck hitch(checked the make sure it was grounding there and it was). Its not where I am gonna ground it, but I wanted a solid ground to make sure that wasnt the problem.

Ive tried to wire it 45 different ways and still I cant get the lights to stay on and I hit the brakes

Do the new trucks need something special to make them work right?

 

did you scrape the paint off of the hitch where you grounded it at?

EDIT: nevermind i reread the post and saw that you KNOW it is grounded so i dont know what to tell ya

 

Have you checked all your fuses? From looking at the trailer wiring diagram that I have I see that there is a 15 amp fuse in the fuse block under the hood that only sees power when the parking lamps are on. That is what I would check to start with.

 

try disconectting the trailer and using a test light to verify the power loss with the head lights on, then we will know were the problem is..

 

thanks everyone.. it seems like the lights get a double feed.. and then shut off for some reason.

Ill play with it today some more and see. Oh and checked that 15amp fuse and it was fine also. Powers going to the trailer, it just doesnt know what to do when it gets 2 signals LOL

 

I think it should be getting a double feed, but one shoud be for the parking lights and the other should be for the brake lights. Sounds like there may be a wire crossed somewhere, although I would expect to see a blown fuse somewhere if that was the case.

 

four wire trailers. are feed like this
Left turn
Right turn
Marker and
ground

That is it, Brakes are turned on by powering up both turns....

 

I got so fed up with the old wires that I ran new wires to the lights and even drilled a new ground. Now everything is working fine. There musta been a short or bad ground from what I can figure

thanks for the help everyone

 

glad you got it figured out, as confident as you may have been in your ground it sure sounds like that was the issue... I hooked a trailer to my old truck and everything worked great, until I stepped on the brakes at night and I had nothing - ground was the issue.

 

Nick, same issue here.. everything works, then with the parking or headlights on it would go dead when I hit the brakes. Let off the brakes and everything cuts back on and works LOL.

I guess it has to have a good ground with all that juice going to it maybe. Atleast I know what to check the next time it happens

thanks again