Whenever I start the Dmax with my Prodigy brake controler it says on the screen OG and that means open ground. I wired it up to the supplied GM harness and it operates without a problem when connected to the trailer. The contrroler did this same thing in my last truck our 2001 Silverado. Why am I still getting this message of an open ground? Do I need to change any of my wirring around? :confused:

If the Prodigy is old enough it might be the version that was notorious for this. Tekonsha said it happened on diesels only. Something to do with the fancy electronics. Might try Tekonsha, they warranty them sometimes for this reason. No other fix that I know of.

If its an open groung message i would splice in a ground tie to the existing harness. Just tap a thread under the dash somewhere and wire that to the ground line on the controller. That way you will have an additional ground if the first one is faulty.

I have the first Gen of the prodigy as well but have not had this problem. I run it on my 2004 Gasser though, i bought a new one for my 2006 Dmax

Well it is a first gen Prodigy....but I used it in both my 06 Dmax and 01 gas Silverado and each truck it said open ground. Other than that it works fine.

Had similar problem(s) when I bought mine three years ago. Two possible issues:

1.There was a different harness needed for the '03 and later Dura max due to a GM wiring change. Got a bulletin and a plug 'N' play adaptor harness from Tekonsha N/C. Forwarded it to both the GMC and trailer dealer. Will try to find the bulletin and post.

2. Bad connection in harness. Try spray type electrical contact cleaner, or remove wires, and clean w/brass-stainless steel brush. Coat w/ silicone di-electric grease.

The Prodigy in my 2006 truck is connected using the 2006 harness. I researched the changes and transfered it from the 2001 to the 2006 harness. I guess its really no big deal as long as it works...just alittle annoying to keep seeing it say OG.

Little fuzzy on the exact explaination, and haven't found the Bulletin, but part of the reason the up front adaptor/new plug in was needed was in '03 trailer wiring harness was changed somewhere. If my memory is correct, you may then have one more thing to do.

Did you contact Tekonsha? Tech line was most helpful, and they supplied the plug in N/C, but both truck and controller wrere new.