No 12 VDC Cabin Power

I have never heard of 12VDC going thru the generator. Do you have a battery cut off switch? In motor homes they call them salesman switches. That is most likely your problem.

Look for a main fuse in the 12 volt power distribution center.
Normally located behind metal plate next to the 120 volt breakers.

Sorry for the confusion... The generator only puts out 115VAC, 60 Hz. However there is a relay located in the same cabinet and the relay is open. It has 12VDC on one side and zero volts on the other. Not sure how this relay is controlled or even if that's the problem. In my camper I believe the salesman switch only turns off and on the lights in the motor home as long as the switches on the individual lights are on. I have access to the power distribution center and there is no 12VDC going to the power distribution center. So, where ever this red wire comes from that is an 12 VDC input to the distribution center, upstream is where the issue is. I will try to post some links to pictures, but currently have a poor internet connection.

Gulfstream does have all their owners manuals avaiable on their website back to about 2000, have you checked there for any info?

I have the owner's manual. Unfortunately it is not much help with issue I am having. Plus, no electrical diagram in the manual. I have contacted Gulf Stream about a wiring diagram, but they said its proprietary information and could not release it. :(

That sounds like a battery disconnect. Switches are commonly over the entrance door.
If you can not find switch, jumper between the two large posts, this should provide power to rig.
Then you need to find the switch, maybe on dash. Owner's manual should have this information.

So when you have 120 VAC available do your 12 Volt DC appliances (lights, water pump etc) work, but they dont when you are trying to run on battery only? Is that the gist of the problem?
You said the converter is putting out power, but did you check at the batteries with the shore power both connected and disconnected?
Just wondering about a dropped ground.

All 12VDC appliances and lights, etc. do not work on battery or from the converter. There is no 12vdc power getting to the distribution panel.

I feel so stupid. There is a series of switches on a panel just as you enter the living area of the camper on the left. Outside light, step, etc. and then a rotary switch that somehow got turned off. Everything was working when my wife left Gunnison. When she got to Ouray nothing was working. Good grief... Everything is working now and we are happy campers. Thanks everyone for your advice and support. CASE CLOSED! :)

Easy fix!
Thanks for the update!
Have a good trip!