Can someone please explain why and/or how removing the instrument panel fuse on a 1992 Cavalier also disables the alternator? I did this once to temporarily disable the speedometer and odometer, which it did, but then later the battery went dead because it wasn't charging. Reinserting the fuse made everything work properly again. WTH?

I'll try

When you removed the fuse you removed the supply to the alternator ROTOR--hence no output.

For the regulator to switch on and cause the alternator to generate the rotor coil MUST be energised from the battery.
This is usually done through the CHARGE indicator/Alternator light. (Path is :- Inst fuse--Charge light--Alternator regulator.
If there is not a bypass resistor fitted (As in some of the linked articles) failure of the Charge indicator filament will prevent the Alternator from producing electricity, so, by removing the fuse you did the same thing. The bypass resistor ensures the Alt still charges although the indicator lamp is blown.

http://www.alternatorparts.com/cs130_sbpage3.htm (This whole article is good info)
http://www.autoshop101.com/forms/h8.pdf (This is a different make but good principles and diagrams)


I have a CS130 alternator on my tractor, same alt as in my cars. One morning I noticed the voltmeter was only reading 12+ volts instead of the usual 14.8. This was the voltmeter reading battery voltage and the fault was a bad filament in the charge light--new lamp fixed it!.


Hope this helps


Alont

So you're telling me that control of the alternator goes through a light on my dashboard, and if the light doesn't work, then the alternator won't work either? So, what if the light blows out? Then would my battery go dead?

^^it would be crippled probably

Yes, that's why the bypass resistor is fitted on some installations-my '93 2.2 does not have it


Alont