12v system only works when plugged in?

[oldbird]

I know there was a thread on this someplace but I can't find it? Today I pulled all the batteries to do maintenance and pulled the breaker box to replace a bad GFI breaker that went bad. Now I don't have any 12v lights etc unless I'm plugged in. I do have power to the jacks and slides. I checked the breaker (fuse?) by the batteries and it seemed OK. I might have screwed something up when I pulled the breaker box because its a REALLY tight fit. I checked each battery and the inteli-power charger and they are fine. Other then that I'm stumped.