I have the same issue with my 1999 Gulfstream Sun Voyager. And have been looking for a thread that could explain fixing the issue. I will read through thoroughly and Post up my results.
I have , at last, driven the RV. I noticed that I have to push the coach switch to on at the steps to get power to the driving controls, ignition etc and, once the engine has fired up both the chassis and coach lights are on at the steps. Surely this is incorrect.
Are there any wiring diagrams for the main battery terminals positions?
I have never found any diagrams specific to your year/model coach. Is yout rig a 30 amp shore power connection, or is it a 50 amp? The images in your early posts on this thread may indicate it to be a 30 amp unit...if so the attached two diagrams may be generic, if not actually useful...
You have yet to answer if your rig is a 30 amp shore connection or the 50 amp variety... Any detail on what you are dealing with specifically is a help in researching potential solutions.
I'm pretty sure that neither one of the drawings is exactly like your older coach -- just presented them to give examples of how such wiring has been done on other GS coaches...
Hopefully they will give you some ideas and a place to start your inspection/evaluation of your present issues.