PITSTOP: Voltage Protection Device (VPD) DTCs P1BA7 and P1B77 - The Voltage Protection Device (VPD) (1) is mounted on top of the HV battery pack. If the HV battery overcharges, the battery cells/modules/case can swell. If swelling occurs, the VPD switch will turn ON, and the Battery Management System (BMS) will receive the VPD ?ON? signal and turn off the Power Relay Assembly (PRA) to prevent damage.