2000 Eldorado ETC
 

I have tried to find answers for this on the internet and can't locate anything direct to my problem.

1. 2000 Eldorado ETC; very good exterior body; Excellent cream colored leather interior; 96,000 original miles
2. Hate to give it up just because of some minor repairs
3. Service Electric Sys light comes on
4. Have determined it might be that I have no brake lights EXCEPT the thin horizontal one on the trunk air foil/stabilizer
5. Just replaced all rear bulbs 4 months ago because turn signals were out; also replaced both relays
6. about a month later the SES light comes on
7. Tried all the fuses; they are okay
8. Can't afford what a dealership would nail me for
9. Can't figure this one out; should be simple but it's not; imagine that

Can someone please help me figure this one out? Kinda dangerous without brake lights.

Thanks, Deano