The ABS Warning Light is an indicative of a failure on the ABS brake system. A qualified technician should diagnose your vehicle as soon as possible. More info here; http://repairpal.com/abs-warning-light
have an 06 uplander, developed the same problem at about 90k, abs light comes on randomly, and now frontend shakes while braking, changed the brake pads, torqued and lube everything, rotors look ok, other steering componets are tight, no visible problems. stuck on what to do next, very irritating
you will need to replace one of your wheel bearing hubs , the part is about $ 150.00 .
The job will take about 2 hours to do .
To test which wheel is the problem take your front tire off , you will see a wire coming from your engine to the hub. Unplug the wire, now with the new hub plug it into the wire and see if the abs warning goes off. If not try it on the other side if the abs lite does not go off then both hubs are bad .