I took my buddys goose neck trailer out a couple days ago and noticed the trailer brakes were not working. I bought this truck second hand a few weeks back it already had the draw-tite controller in it (it also lights up when I brake) it has a pollak 6 prong plug in the bed & the normal gm towing package hitch looks like a 7 prong plug under bumper. Well his trailer had the big plug so we just plugged the trailer in the hitch. To make a long story short can anyone help me check these plugs to see if they are working correctly. I do have a volt meter but I am no electrician. Should I replace that small plug in the bed or maby I can buy an adapter for it so that I would have both plugs. Just wondering if someone can point me in the right direction to get it all working? THANKS...