Glad you found the problem. I encountered a problem with a short in the head of the 30 amp male plug. It kept tripping the GFI at the campground. A well meaning Industrial Maintenance man on the next site ran a jumper from the ground to neutral in my fuse box without telling me and it kept tripping. After I got home I replaced the plug and it still tripped the GFI on the garage circuit. I looked closely at my service manual and discovered there was no such wire mentioned before in the diagrams. I removed it and the problem went away. I found later that it is a common occurence to do this in industrial work that does not involve GFI.
'01 2500hd ext. cab, 8.1 litre gas, 5 sp. Allison auto
3.73 rear end
Mag-Hytec rear diff cover
Amsoil Dual by-pass oil filtration system
Amsoil synthetics all around
265 watt AM Solar, Inc. system