Congratulations on your new sunny!
Finding a wiring diagram is going to be complex on your 40 year old camper.
That said, we have several of us that can help with troubleshooting your system if we can see what you have. A prior owner may have done some modifications.
There should be a power converter in the area inside the camper where the outside 120 vac power cord comes into the camper. Look down low in a cabinet, under a couch, or behind a wood panel etc. Posting some pics of the power converter with a brand and model is a good start. If you feel comfortable with electrical, take the cover off with the power off and take pics of inside and post. There also may be a 120 vac breaker box their too. Take pics of that and any 12 volt fuses.
Are you having any issues with the DOT lights? The clearance, stop and turn signals? Those we can hunt up a generic trailer wiring sketch if needed.
Let us know some more what is not working and we can try and help better.
Hope this helps
Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
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