Grinding , vibrating coming from under truck.

Hello, sounds like a possible mechanical brake system issue, or perhaps even an anti-lock brake system issue. If there is a false activation of the anti-lock braking system, it will grind and the brake pedal will kick back and other issues will be present. Seek guidance at a local shop near you for hands on testing to duplicate your concern and provide some diagnostic direction. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops