FORD 2001 F-550 v.1 - Manual (Page 167)

Power distribution box
The power distribution box, trailer
tow and electronic shift on the fly
relay blocks are located in the
engine compartment near the brake
master cylinder.
The power distribution box contains high-current fuses that protect your
vehicle’s main electrical systems from overloads.
Always disconnect the battery before servicing high current
fuses.
Always replace the cover to the Power Distribution Box before
reconnecting the battery or refilling fluid reservoirs.
If the battery has been disconnected and reconnected, refer to the
Battery section of the Maintenance and care chapter.
Roadside emergencies
167