abs light

my abs light comes on but does not stay on all of the time does anyone
know what this problem might be? i thought it was the power brake booster i replaced it but that wasn't it

Mine does that sometimes , espeacialy when i was having brake rotor and pad problems.

it has just recently had a brake job

now the brake pedal slowly goes to the floor when pressure is applyed

i replaced the master cylinder now i have a good solid brake pedal but the abs and low trac light still comes on NOW WHAT?

possible wheel speed sensor, check it for codes