DTC U0121: Lost Communication with the Anti-lock Brake System (ABS) Control Module: Action
WARNING: This page is about a different car, the 2012 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.
CARRY OUT an ABS module self-test. If the scan tool indicates the module is not responding, REFER to MODULE COMMUNICATIONS NETWORK - F150 to DIAGNOSE the network communication concern. If ABS module DTCs are present, REFER to ANTI-LOCK BRAKE SYSTEM AND STABILITY CONTROL - F-150 to DIAGNOSE the ABS system fault.