My winter beater, aka my '05 Mazda 3, will not charge my battery. I've replaced alternator, albeit a used one, but I'll negate the possibility that its no good upon further inspection of other parts. The 2 wire plug that attaches to the alternator is where I'm focusing my attention at the moment. This is from my understanding that one of those is a constant 12v (battery), and the other will read ~1v and upon startup will read around 12-13v as this is what will trigger the dash light. At the moment I am not seeing 12v at either of those wires(engine off). Should the 12v, not the one for warning light, be constant 12v even if vehicle isnt running? The other larger wire, charging wire, is reading 12v. Ive gone over all fuses in the engine bay and all seem ok. Oh, and I did try to get my alternator tested at parts source, however they do not have the correct adaptor.