I just installed this in my 2003 Excursion, everything went smoothly with install and unit powers up fine. Connected it to a trailer using the 7pin connector, at first it would not recognize that it was connected. We tow this trailer all the time with 2 other vehicles and the wiring is intact on the trailer- brakes and lights all work fine.

So I figured the connector on the truck was probably dirty or a little rusty although this truck spent the first 4 years in Texas and the undercarriage is in great condition. So I cleaned the contacts with some WD40 and emery cloth and wiggled it around some. Still no lights but then the P3 registered that it was connected. A little more finagling around the connectors and the lights worked- hurray!!

So I head out on the road and adjust the brakes and all is good. A few more miles down the road and when I hit some bumps it starts flashing that the trailer is not connected and the trailer brakes come on, this happened about 5 times over 15 miles. Then I hit a real bad stretch of road and it stays that way and the brakes on trailer lock up. I pull over and spend about 15 minutes messing with it and no luck so I just leave it unplugged and tie a headlamp on the back and limp home (it was dark)

I was reading what I could find and think its probably a ground or loose connection somewhere. Someone posted that there is a connector on the drivers frame rail near where the spare sits which I will check tomorrow when it stops raining. Any other spots I should look at? Where does it ground? The fuse is still ok

Thanks

 

I'd suggest checking fuses and making sure the connections on the trailer and truck are clean without any corrosion...per your own suggestions, I'd check for electrical shorts as well...

 

Thanks- connections are clean and the trailer plug is new from this summer. Going to connect the other trucks later to try and rule out the trailer.

 

You may need to replace the 7 pin connector on the vehicle side. There are aftermarket ones that hook up directly to the excursion. You'll need to turn it 90 degrees and drill screw holes to mount it.