You can do some marvelous stuff with some pretty basic stuff
Go to a parts store or RadShack and buy a basic digital multimeter One "designed" for automotive would be good
Buy a generic "12V test lamp." These are incredibly handy.
Now, if you have a stock electric system, there are several pitfalls along the way that Ma engineered right into them. They are:
the bulkhead connector, never all that good, may now be old, corroded, deteriorated, along with wire sizes that were never "too big."
the ammeter. On many dash clusters, the wire terminals clamp the "whole thing" together, so that if the only nuts get loose, it starts to heat up, then gets more loose, and you have a snowball
A few things you can do before the parts store:
Go to Rad shack and buy a package or two of their large size clip leads. Dig into their "components" drawers, and buy some bare alligator clips. Two or three sizes are good.
First thing to determine, is, IS THE ALTERNATOR in a condition to work, so take a clip lead, and pull off the only "push on" small wire at the alternator. Use a clip lead and jumper to the large stud--which SHOULD BE HOOKED TO THE BATTERY. So don't short it.
Don't leave this clip lead on any longer than needed to take the test. Start the car and ease up the RPM's until you are simulating "medium cruise" that is, say 40-50 MPH simulated. If the ammeter works, you should see a charge.
IF NOT, the possibilities are:
Alternator has serious troubles
Alternator has bad brushes
Alternator output stud is NO LONGER hooked to the battery. (Bad wiring)
Take your new meter, and measure voltage with engine off from block to alternator stud. IF you show 12V, Fire up the engine again, and kick in the "fast idle cam"
Measure the voltage again from the alternator stud to ground. If it's low, say, 12V or less, you have an alternator problem
If high, say 16-18 or higher, you may have either a disconnect between the alternator and battery, or something in the ammeter circuit.
Double check, engine running "fast" by measuring voltsge at the battery pos post. IF it's low, continue below. If it's high, close to alternator stud measurement, the alternator can work
Next, devise a wire, say, no10, that you can "jumper" right from the battery positive to this stud.
Rerun the test. If you now show that the battery and output stud voltage are close, and running high (16V or more) with engine running fast, then you may have a disconnect in ammeter/ bulkhead circuit
OK let's say the above tests show that the alternator works, but when you hook things up normal you get----nothing.
So now find the regulator, and clip a lead from the ign terminal of the regulator to the field terminal. Only two terminals so there's "only two."
Now the car should charge more and more as you rev it up, same in first tests
If so, it's starting to look like you have a regulator problem. With this test "going" take your meter and hook to ground, hook the other here at the regulator where you have the clip lead. The voltage you read should be "close to" same as battery.
If you install a new regulator, check your charging voltage and post back. You need to make sure regulator is properly grounded to "actual ground" that is, battery neg. post
