1999 Pontiac Montana ABS indicator light

1999 Pontiac Montana. 121,000. I just bought this van and the ABS light continues to come on and stay on at intermitent times. It will come on after sitting for a little while but when I shut it back off and start it again it goes off. then it will return after a few minutes of driving. I see that the last owner replaced the front brake pads, but I am not sure if they needed to be bled in a certain sequence.

Also, the airbag indicator is doing something like that also. Not sure what to check on those. It will come on and go off any time it cares to.

Thanks.