Yes, there was some corrosion on the positive terminal, I've cleaned it with baking soda and a brush.

Is it safe to pull the plastic back off the connector at the alternator, and connect my multimeter there? Just want to be sure about where to test, lest I fry something.

Was it extremely crusty? If so I would look closely at the cable for internal corrosion.

And yes, it is safe to remove the cover; however, be mindful that you are working with Voltage.

Hello,
Well, after raining all week, the skies are finally starting to clear up... I should be able to take a look at the wiring after work today. To test continuity, I don't have to have the engine running, do I? According to the wiring diagrams, the two large cables connecting the alternator to the starter and battery are always hot. So, if everything is connected, I should read the same voltage from the positive battery terminal, the connector to the starter, and both cables running to the alternator, right? Of course, I could test continuity by measuring point-to-point resistance, but the voltage method seems easier. Is it necessary to remove the connection to the positive terminal of the battery when inspecting the alternator cables, as LarryBible instructed me to do? Also, the wiring diagram shows 2 cables coming from the alternator, both are shown as being connected to "B+" on the alt, and terminal 30 on the starter. Any idea why there are two wires seemingly connecting the same two points?

Please review the previous post and the directions regarding the "voltage drop" test over the line. The circuit must be under load therefore the vehicle should be running with lights, blower, flashers all on.

Your meter is connected (Red) to Battery POSITIVE.
(Black) to the positive connection at the ALTERNATOR.

If you get a reading >.500mV you have a high resistance problem "somewhere" between the BATTERY and the ALTERNATOR, the next obvious connection in the circuit is the "Starter Motor" connection.

OK, hopefully I'll have more time on Saturday to charge the battery and do the test as you described. Getting the battery charged can be a pain in the butt, since I either have to lug the battery inside or run extension cables out my window and across the sidewalk! I didn't have much time to work on it last night, but I spent some time looking at the wiring diagrams and tracing the cables that run from the alternator to the battery, trying to figure out what I could test without the engine running. There is a heavy gauge wire that connects the positive terminal of the battery to the starter. From there, there are two wires that connect to the alternator's B+ terminals. There is also a thin blue wire that I believe connects up to the idiot light. With the engine off, I put the negative lead of the volt meter on the negative terminal of the battery, and tested the voltage at the starter connection, and the wires that run to the alternator. I read ~12V at all points... which means that I at least have some continuity. That still doesn't rule out a high resistance problem, as you mentioned. Rather than test for a voltage drop with the car running, would it make sense to measure the resistance of the wires directly using the ohmmeter function of my multimeter? What about that blue wire that goes up to the instrument cluster... could a problem with that wire prevent the alt from charging my battery?

Thanks,
Nate

A voltage drop test is what I consider the "Dynamic resistance Test!" The device is "ON" which requires X amount of "Current" to operate to full capacity.

The only way you can determine how much "Current" loss you have over a given circuit is with this test, as well the circuit must be operating. The higher your voltage reading the more current you are loosing between the two main points, the connections in between can be considered sub points. When you get a high reading on your volt-meter you simply work backwards to the first sub point working back to the “Source” until you get a low reading. When you get a low reading it pinpoints the problem to the previous high reading test point.

Hello,
Well, I finally took some time from enjoying my long weekend (hope you're having a good one!) to take a look at my car. With the car running, headlights, fog lights, hazards, blower, radio all on, I didn't find any voltage drops between the positive terminal of the battery and the alternator. I tested the connection at the starter as well, no drop there. I connected the negative terminal of the voltmeter to ground and re-tested everything, the voltage reading at all points was the same, about 10-11V (decreasing slowly over time as the battery drained).

I just noticed one more thing... there's a fuse holder connected to a wire that runs from the positive terminal of the battery down to the battery tray. The fuse inside the connector is blown. Any idea why that would be there? It doesn't look like an OEM part.

Well, I just ordered a voltage regulator from FastLane, I figure it's worth a shot, and even if it doesn't help, it'll be good to have an extra one on hand, "just in case". Overnight shipping was cheap, so I guess we'll know soon...

Ockham's razor strikes again... the new voltage regulator worked! As soon as I compared the new regulator to the old one, I knew the old one was broken... the small tab that connects to the positive contact inside the alt was broken off... so, I guess there's more that can go wrong with the voltage regulator than just worn brushes!