So I have a 93 Chevy Blazer 1500 Silverado and I love it! It has over 250xxx on her and is still running strong with little rust for a Wisconsin vehicle. So the problem started before Christmas. When i would barely apply the brakes in the snow the ABS would some on and make a strumming noise and would seem to slide a little. Then a couple weeks ago the brake light came on and i had only front brakes. It uses fluid, i have to fill it once a week or so, but i crawled under the other day and cant find a leak anywhere in the line where it is wet or around the rear wheels. I have read quite a few posts on here but couldnt really find 1 that fit quite right to what i was looking for so any help would be highly appreciated!! Thanks..

 

Have you tried pulling the rear drums to inspect the shoes and brake cylinder? My '05 work truck had so much crap in there from mud, shoe dust..etc and a pretty good lip on the drum itself that when the cylinder finally pushed all the way out, yes I REALLY REALLY needed to do a rear brake job apparently, no fluid was evident until I pulled the drum.

 

You need to fix that and probably bench bleed your master cylinder (I bet that's why your brake light is on).

Just replace both rear wheel cylinders, one of them probably leaks (they're like $6.50 at napa no core charge)