Thanks for all these advices. The multimeter thread is great. Are there any particular check points on the alternator?
I promise to check the fuse-link also.
Do I have to match the voltage regulator with the alternator amperage, or will any regulator do the job?
As far as I know any will do. Hell, there are even people mixing and matching ford regulators with dodge alternators. (not saying you should) I also know people are using older external regulators on newer pcm controlled alternators (fuel injected)
Do yourself a favor, and don't buy your electronics/modules ect from autozone. NAPA should be able to set you up with a higher quality piece for reasonable.
There are a few check points on the alternator. A large positive terminal (battery cable connected) and the engine block. Alternator is case grounded. There is also a small negative and positive wire, either blue/green or red/white depending on year.
With a few simple multimeter measurments, you can diagnose the entire system in about 5 minutes.
Those "free test" places, cough-cough....autozone, are not very good at diagnosing problems. That's not their job. They sell parts.
Oh, btw, there are a few confusing instructions in that write up as far as where to put the multimeter leads. If you suspect a run of wire may have high resistance, BOTH leads go on the same wire, or atleast same polarity. This tests for connection/wiring issues.
If you simply want to know how much voltage is in your battery, or how much the alternator is producing (positive alternator stud to engine block) then you go negative/positive. Otherwise for those connection/wire resistance tests, keep 'em both on the same side.