jvance1966-
First off, welcome to iRV2!
Second, you should add a signature to your user profile. A signature is appended to every post. Most people include information about their coach, so they don't have to type that out each time. Some folks include other info, such as about their toad. Instructions for adding a signature are
here.
If your coach was on a Ford chassis, the answer would be more cut and dry (Ford provides wiring for a trailer electric brake controller). For the Workhorse, the best I can suggest is to get a signal tracer and clip it onto the brake controller wire at the coach hitch connector, then see what you can find under the dash. This assumes that there is a trailer electric brake controller wire terminated on the coach hitch connector.
You can buy signal tracers online or at some of the home-improvement box stores.
If you have to run a wire from front to back, run a second 10 or 12 AWG wire and set it up for a fused, ignition-switched 12V charge line n the correct pin of the 7-pin connector. That assumes Gulfstream did not provide a charge line on your coach- it may have done so.
Welcome to IRV2! We're sure glad you joined the gang! 
Linear Mode
