FORD 2010 F-550 v.2 - Manual (Page 311)

WARNING: Always disconnect the battery before servicing high
current fuses.
WARNING: To reduce risk of electrical shock, 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 Specifications chapter.
The high-current fuses are coded as follows:
Fuse/Relay
Location
Fuse Amp
Rating
Protected Circuits
1 Relay Blower motor/Variable blower control
(Dual zone climate control)
2 Relay Electronic shift-on-the-fly (ESOF)
Lo-Hi
3 Relay Heater mirror
4 — Not used
5 30A* Trailer brake controller (TBC)
6 40A* Anti-lock brake system (ABS) module
(Pump)
7 30A* Upfitter auxiliary switch #1
8 30A* Upfitter auxiliary switch #2
Roadside Emergencies
311
2010 F-250/350/450/550 (f23)
Owners Guide, 2nd Printing
USA (fus)