My dads friend has a 97 blazed and he had to slam on the brakes yesterday, ever since when he has to brake the dash lights come on everytime, wtf would cause this?

 

do the brakes feel funny ? possibly a leak ?

check the fluid level also

 

Yep sounds like he blew a wheel cyndler calibur or something
spungy brakes look for wet spots on the ground also check the insides of all the tires to see if there wet if 1of the tires are wet that would be where your leek is

Now if you cant finds a leek and the brakes feel and are working fine your proportion valve could be stuck give it a tap with the butt of a screw driver