Can someone tell me if I possibly did something wrong while changing the brake pads on my blazer? The ABS light and system is now acting up.

 

i take it you did front brakes?
did you re-connect the abs sensor harness at each wheel?
check those out. they run from back of hub bearing to just above towards front of frame.
check brake fluid levels.

need some info on your ride..

 

I like to open the bleeders before I squeeze the pistons back into the calipers, that way the fluid comes out instead of pressing the dirty stuff and crud back up into the ABS system. You may have crud in the ABS now, I reccomend bleeding your brakes out really well - Suck the old stuff out of the resevoir till its empty, and put in new fluid before bleeding. Also check if you banged the wires for the ABS harnesses while hanging the calipers to change the pads.