i just switched from a 2006 gmc envoy to a 2006 chevy trailblazer ext. the envoy delivered power throught the trailer harness to run the 3 way fridge in my camper on 12 volt while driving. the trailblazer is not doing this. they are the same vehicle so i am confused. is there a connection that has to made somewhere that i dont know about? i am leaving for a camping trip this friday and need to fix this. so i will be gratefull to anyone that can help me out. it has a 7 pin round connector, six flat around the outside and a round one in the middle. the lights and turn signals work, by the way. thanx to anyone that can help me.