the ABS light in my '93 classic is on and I can't figure out why.
when I start the light is off but when I start moving I can hear what sounds
like a buzzing sound coming from the passenger side. any ideas?

The wheel sensor may have come loose. I would check that.

Originally posted by eric96ser
The wheel sensor may have come loose. I would check that.

where is it located?

You should have a wire bolted to the strut. Follow that. None of my cars have ABS, so that's the best description I can give you. Sorry.