Originally Posted by RvBill3
On my Chevy Avalanche the charging wire for the 7 pin was not connected under the hood. The owners manual explained this. I had the dealer connect it although I could have done it myself. Also if you are trying to draw power from the TV make sure it is in tow haul mode if equipped. That increases the idle speed which ups the output of the alternator.
On the early (2000's) Chevrolets/GMC's, there is a large fuse/relay box under the hood on the drivers side. There is a large "MAXI" fuse for the 12v feed to the 7 pin trailer connector. This fuse is NOT installed at the factory even though it may come from GM with the tow package. If you look at the inside of the cover, the chart will tell you where this fuse goes and what amperage it should be (40 amp. in my case). Now, that being said, if you install this fuse, and leave your TV connected to the TT (such as when dry camping or parked in the driveway) and NOT connected to shore power, the TT's "always on" 12 volt systems as mentioned in my previous post, will "kill" both batteries (TT & TV)!
The good part about 'hooking up" the fuse is that on long trips, it will help keep the TT's battery "maintained" so that you can travel with the fridge running on propane and the 12v igniter for the fridge will light the burner to keep the fridge running cold.
The original concept for the manufacturers running a dedicated wire to the 7 pin plug was for enclosed utility trailers that have 12v lights inside. With the TV and utility trailer plugged in, the interior lights would work as well as keeping the little motorcycle type battery for the electric brakes charged in case of a "breakaway".