2000 F150 Rear Brakes problem?
Do you have drum or discs in the back. If you have drums it could be a leaky axle seal slobbing up the shoes and causing the drums to grab. I assume the back brakes are locking up. If its the fronts, and your abs light is coming on it could be a modulator problem. Its really hard to know why the abs light is coming on without a scanner to see what kind of codes it is setting.