Brake Pad Wear Light Still On

[BriceW at webtv.net]

I installed new rotors and a new pads and the brake pad wear light still
comes on.
It comes on about 3 minutes after I start the engine and begin to drive.
This light was on for a month and a half before I changed the pads and
rotors.
When I push the "button" on the tach it goes off and stays off until I
restart the engine and begin to drive and after about 3 minutes it comes
on. It doesn’t come on right away but takes some driving and shifting
to come on.
I have tried disconnecting the battery and the fuse to no avail.
I remember that this was a common problem and wonder what the solutions
are.