i have a 2000 4x4 blazer..
i bought new shocks for it yesterday,and on the way home my abs light came on.nothing to do with the shocks,i just got em cause i needed new ones...anyways the light came on..
i noticed the brakes sqeeking on the indicator too,so i fuged id go get new ones,thought maybe that had something to d with the abs light. so today i put the new shocks all the way around and new front rotors and pads. i pulled teh sensor out and wiped them off and scuffed em up with some sand paper. put everything together. reqached in a fired it up and the light was out.. got in to move the truck and the light comes on. ive got it narrowed down to the light coming on when i sit in the drivers seat,and it goes off soon as i get out.what gives? did my fat butt short a wire under the seat? well,let me think,it went on with the wife sitting there too..shes only 110#

pics of the wife if needed

 

mostl likely the speed sensor. if you can get it scanned it will tell you for sure which one, it will either give you an erratic speed or no speed. if you do get ahold of a scanner, gm vehicles are set at 3mph default at 0mph.
i know when i tried cleaning mine the tabs are very flimsy and easy to break. bad news only way to replace is new hub bearing. and yes i tried the track down a buddy that just changed his bearing, take his old sensors and put them in. it didn't work for me. needless to say i got a new bearing with the sensors and it fixed it.

 

I had no problem changing the one in my 99 Jimmy. Around $50 from my local parts store. Removed the caliper and bracket and then removed and replaced the sensor via the single mounting bolt. Did something change after my model year?

Also I believe there is a TSB relating to the build up of crap around the hole that the sensor sits in which changes the air gap and makes the ABS engage at lows speeds even with no wheel slippage. You might want to pull the sensor again and clean the surface around the mounting hole and try it again.

 

yes there is a tsb, kyle gives an overview of how to clean them, i did track down one part store that would sell the sensor separate. the only problem was the sensor was the exact same price as the hub/bearing which included the sensor, mines a 2000 and i don't know if they changed

 

I had the same problem with my ABS light on my 2000 blazer. But a couple days ago i had my hub bearing replaced and now it does not come on at all. I guess the sensor itself on that side was bad or something hope this helps

 

My 99 Blazer is doing the same thing. The ABS is coming on with slow righthand turns, sometimes slow lefthand turns. And today coming to a stop on front of a house with a puddle the abs came on. The brake pedal is traveling to far too. I better fix it before I hit something.