Anti-lock brake system light comes on

hello;
when im driving my car for awhile my anti-lock brake light comes on in the dash. this happens when i use the brakes in town. it stays on till i shut off the car. they seem hard to push on the brake pedal, any suggestions on whats wrong.i checked the brake oil and it full. I have 91 Grand Prix GT
Don

check brakepads and calipers? Midas will do it for free...

well i can see the brake pads and they look almost new, i think they were changed about 2 months ago. what i need to is why my anti brake light comes on in my dash does anybody know yhe its coming on
Don

if the abs light comes on, it doesnt mean the brakes dont work. it means the abs or trac ctrl controller isnt working, one of the abs sensors maybe defective or unplugged or damaged or somthin like that...

90% of the time that the abs light comes on the abs sensor at the wheel bearing is bad its about a $525.00 repair at the dealer have it checked out

thanks for the imput so far , i;ll have it checked into by my mechanic
Don