intermittent charge light

My charge light has start going on intermittently (I've got about 190K on my '95). It tends to go off when idling. I tried the easy fix of cleaning up the battery terminals, but I guess I'm not that lucky today. What is the diagnostic sequence for this? Are there any good pics or videos about how to diagnose my alternator?

 

Measure the voltage across the battery terminals.
If the alternator is working properly, it should be around 14 volts (motor running).
A good battery (with motor NOT running) will measure about 12.5 volts.

 

You might want to check the belt tension

If you have a intermittent problem

When did you last change the belts ??

 

also check the for bad connections on the alternator.

 

get your battery load tested as well