Plug & Play trailer wiring harness, now tail lights don't work
 

I ordered the trailer wiring harness from A.B. that is the plug and play proposition and installed it. While it was an easy install, I was checking my taillights and brake lights to make sure everything was working and now I have no brake lights with or without running lights on. No third brake light as well.
Any ideas?

Yep, sell it to me its messed up:-)
does everything work fine when you unplug it?

I need to edit the title of this post. It's the brake lights, not tail lights. I unplugged it and still nothing. Checked fuse 25 for the brake lights and reverse lights, it's good. It's not the brake light switch as I think if it's bad, you can't put it into gear.

No facking clue. I can't imagine coincidentally that the wiring got messed up in the same 24 hour time frame that I installed it and then checked the brakelights.

The ignitiin must set the Run position. Just before starting the engine. Do this then they will come on.

The truck was running when I was checking the lights.

Have you checked for voltage yet.

not yet

That makes no sense. They are grounded at different locations so it isn't a ground. They get power from the same fuse that feeds the start inhibitor and the reverse lamps so if they work the fuse is good. Are you sure the brake light switch is good? How about the brake light bulbs?

I installed the same one from AB back in January and installation was a snap and everything works fine.

Not sure on the brake light switch. I've just read if it's bad you can't shift but maybe there are levels of it going bad. Maybe this is the 1st stage and whilst I can still shift into D, maybe that will soon fail.

I haven't bothered checking the bulbs as I thought it would be to coincidental that the three bulbs all burnt out at the same time.

I've checked fuses, jiggled the wiring in the right hand side tail light thinking that when I removed it, I created a short with a loose wire or something.