alternator light at 4000 and above

[doug]

I've never had this happen before, and have not heard of it so I need help. My alternator light comes on around 4k rpm and stays
on while at or above 4k. No problems at any other times and the system is recharging OK since if it wasn't it would have been dead by this time. I haven't done a thing, like clean terminals, etc. Anybody got any ideas?

[1988starter]

Put a voltage meter on your battery while the car is running and see what the alternator outs out then have a friend rev the engine till the light comes on and see if what the volage is. You should see between 13.5-14.2 volts

[POS carb]

check the belt tension 1st, it doesn't always squeal when it's loose
2nd could be worn out brushes

[Xulfiqar]

your alternator brushes are worn out, I got the same problem - relplaced the brushes and good as new...