Battery light comes on then goes away sometimes.

This just started yesterday when I noticed the battery light came on when I started the car (91 ls 4dr auto) and it went away after a while of driving. Sometimes it doesn’t come on when I start the car but other times it’s on when I start the car until I get to destination or it comes on when i start the car and goes away after awhile. According to my voltmeter it looks like the battery is holding a charge so wouldn’t that mean my batter and alternator are working fine? Also a couple days ago I pulled the ecu fuse because my car had been broken into and wanted to make it a little harder for them to steel the car if that’s what they planned on doing later on. I didn’t actually check the alternator not really sure how to do so, so maybe it could be that or maybe a bad ground? This morning I just noticed that when I press on the brakes the dash lights dim a little and there is a click sound that come from the shifter area when i release the brakes. I can try to check the alternator and grounds but not sure if that’s the problem or not so that’s why I’m asking you guys, thanks in advance.

UPDATE:

I had no choice but to drive the car for work today. Ended up having AAA jump me when I went to leave my destination (battery was dead?) and I guess I ran off the alternator all the way home. On the way home my dash lights were lit up for a while but went away, the tranny wasnt shifting right, the power steering was getting harder and the CEL came on, not sure if that happens if the car is loosing juice. I replaced the battery and the battery light is still on. So I’m guessing it’s the alternator? I’m going replace it tomorrow and see what happens. Any advice or suggestions?

Replaced the alternator and no more battery light. Also the dash lights seem to be brighter and when I step on the brakes nothing dims. So I guess the problem is solved, we’ll see. Alternator definitely needed to be changed considering it was original to the car.