With out an iota of knowledge about that year BigFoot
, I can chime in with the following:
1) Guessing that the wiring on a 30 y.o. trailer with untold previous owners and changes will match a wiring diagram is a death march in itself.
2) Few, if any RV builders were all that consistent in as-builts matching printed wiring diagrams or color codes.
3) 95% of all trailer wiring is generically the same. Ask a question about your specific problem and you should get better help.
4) Personal Opinion.... If it's the original converter/charger, now is the best time to upgrade to a modern converter/charger/AC-DC Distribution panel. You can find all of this and much more in the Progressive Dynamics PD-4045 power chassis.