Power Supply Distribution Box
The Power Supply Distribution Box (PSDB) is located in the right side of the luggage compartment, rearward of the Battery Junction Box (BJB). The PSDB incorporates two banks of Metal Oxide Semi-conductor Field Effect Transistors (MOSFETs).
The MOSFETs are activated by the Body Control Module/Gateway Module (BCM/GWM) assembly:
- To switch the vehicle loads between the batteries during an auto stop/start event
- For charging the auxiliary battery.
The PSDB receives a battery supply direct from the primary battery to BAT1 terminal and a battery supply from the auxiliary battery to BAT2 terminal. The PSDB also incorporates a microcontroller, which receives commands from the BCM/GWM assembly via a Local Interconnect Network (LIN) bus connection. The PSDB connects or disconnects either the primary or auxiliary battery to the vehicle loads according to the BCM/GWM assembly commands. In addition, there is a diagnostic connection between the BCM/GWM assembly and PSDB, to detect faults with the PSDB.
The MOSFETs in the PSDB have a fail-safe body diode mode. This mode will provide there is always a connection from the primary battery to the vehicle loads in the event of a failure in the PSDB. At least 60 A can be supplied to the loads in this mode. The BCM/GWM assembly will detect such a failure and will shut down non-essential loads so as not to overload the PSDB.