HELP!! On electrical..

[justinlogue5_0]

I have a early 99 F250 and I can't get the brake box to work. It was installed by the previous owner. Its a Tekonsha brand. Let me tell you what I know. The pig tail on the truck and trailer is all new and making good contact. At the brake box under the dash the wires hook into what looks like factory wire harness. The light on the box does not light up like it is supposed to. Test the wires and every thing is hot when its supposed to be. When you touch the test light to the blue wire(hot to trailer) the led light comes on and when you hit the brak pedal the test light lights up and the led light turn red like its supposed to. But I cant get it to work any other way. Should I bypass factory wires and hook it up straight? Is there some thing I am missing? I am not the best when it comes to auto electrical. Thanks ahead of time for any and all help!

[gary2070]

I would go to their website and see if you can download instructions for that particular model or maybe find the contact section for them and send them an email or a phone call?

[jbeasts10]

It almost sounds like the trailer is not grounded.Is the ground on the truck connected to the chassis?Is the ground on the trailer plug connected to the trailer?
I am trying to refresh my memory on this subject,I use to install trailer hitches and brake controllers every day.That was about 8 yrs ago though.

[justinlogue5_0]

Ground is connected to the frame rail. Trailer plug is connected and making good contact. I sanded all the connections and bent them a little to make sure its making a tight contact. I am wondering if I should cut it loose from the factory harness and wire it in straight to the trailer plugs?

[justinlogue5_0]

UPDATE!!! After several hours of following wires I did finaly find a bad spot in the blue wire sending power to the pigtails. I patched it and relocated it to keep it from getting damaged again and all is good now! Thanks for the help guys