i have a 2000 f150 4x4 that i constantly tow a trailer with. for some reason i have running lights but no brake or turn lights. i have searched exhaustively and i still havent found the answer for my problem. all the lights on the truck work and i've checked all the fuses, relays and light bulbs and they all seem fine. also i have a 4 pin to 7 blade adapter on the truck with the LED test lights and they all light up with the respective light that "should" be on on the trailer. i have checked the wiring on the trailer and replaced some of it and its all fine. thanks in advance for any help.

 

???

 

That's how mine is and I'm thinking it's a factory defect they didn't catch.

 

Well and also mine have never worked it sounds like yours did work than just stopped??? In that case it sounds like it could be a short some where.

 

but i replaced the ground to the trailer wiring and the four pin connector on the trailer and the rest of the wiring looks fine

 

i dont know

 

It could be a short between the 7way and where it meets the plug next to the spare on the inside of the driver's frame. I'd try pulling that plug apart, cleaning the poles and see if that doesn't help. I had a similar problem when I upgraded from a 4 pin, to a 7 and then put a 6 socket on the end. It sounds like your getting enough current to light up a led, but not a bulb. Try sticking a multimeter in and seeing what kind of voltage you have going through. Could also be your 4-7 is fried. If you can, see if there is a difference in voltage between you 4 pin adapter and your 7 plug on the truck.

 

I was having similar problem with my truck. I ended up replacing the adaptor thing that you plug into the truck. I got one for $20 at autozone. Its very easy to install, all you have to do is rewire the wires

 

Not the adaptor but the 7rv blade that you plug the adaptor into

 

Time to grab a multimeter and find out of your 7-4 is outputting because they can go bad. Remember, to have LEDs on these circuits resistors have to be present in the adapter to Keep it from burning the LEDs out.