Power Distribution

The vehicle power distribution system provides battery power to the electrical and electronic systems.

The following components make up the vehicle power distribution system:

• Battery Cable Access (BCA)

• Vehicle Power Distribution Module (VPDM)

• Optional Cab Load Disconnect Switch (CLDS)

Vehicle power is supplied by the batteries to the battery cable access (BCA) box. The BCA front wall pass-through is the primary interface through which battery power gets transferred from outside the cab to the inside. It is located on the passenger side of the engine compartment front wall. This provides a disconnect point for harness service, testing, and replacement. See Fig..

Fig. 1,  BCA

The power supplied by the batteries goes to the vehicle power distribution modules and the Single System and Actuation Module (sSAM).

The PDMs are fuse power distribution boxes. They provide power and circuit protection for powertrain needs, cab functions, and various stand alone modules. They also supply power to the emergency power supply circuits in the event of a module failure. The PDMe is located in the engine compartment on the frontwall. See Fig. The PDMi is located in the vehicle electronics bay, behind the passenger-side dash panel. See Fig.

Fig. 2,  Power Distribution Module (PDMe) in Engine Compartment

Fig. 3, Power Distribution Module (PDMi) Behind Right-Side Dash

Depending on a vehicle's specifications, the fuses and relays installed and their locations can vary. Each PDM inside cover has a fuse map with an image of the fuse layout for that vehicle.