Thank you!
Response:
1) my 07 f550 does the same thing and ford dont know why but has been doing this for 170000 miles with no other problems
2) Number one cause of this issue is a failing Speed sensor. The speed sensors are located inside the front hub bearing assemblies. This means you have to replace the entire hub bearing......
Or, you can just remove the ABS fuse or Relay to deactivate the ABS system. The ABS will no longer work which means it will no longer give you a problem when it is dry out. Just won't work in the wet, icy roads either. Once you save up the money, you may want to have the ABS system fixed.