The 2023 Ford F-550 Super Duty is a P708-generation commercial chassis. Its factory electrical architecture is shared with other 2023 Super Duty trucks, but the F-550’s trailer equipment, electric trailer brakes, four-wheel drive and AUX upfitter circuits deserve particular attention.
Many F-550 trucks leave Ford as incomplete vehicles intended for specialist bodywork. A dump body, tow-truck system, hydraulic lift or other added equipment may have its own fuses and relays. Always check the body manufacturer’s wiring documentation as well as the factory fuse boxes.
Where are the fuse boxes in a 2023 Ford F-550?
Engine compartment: the under-hood power distribution box protects high-current circuits for the ABS, steering, starting system, four-wheel drive, trailer equipment and powertrain controls. Open the hood and locate the covered power distribution box; release the cover retainers and use the identification diagram before removing a fuse.
Passenger compartment: the interior fuse panel is behind the access trim on the passenger-side footwell. Remove the access panel carefully to expose the fuse positions. Some upfitter wiring is also routed through this area.
Engine compartment fuse box
Ford does not use every position number consecutively. The table preserves the manufacturer’s listed positions, including unused and spare locations. Positions 24, 25 and 27 have different ratings for gasoline and 6.7-liter Power Stroke diesel applications.
| Position | Amperage [A] | Protected circuit / function |
|---|---|---|
| 1 | 50 | Cooling fan 1 |
| 2 | 50 | Heater |
| 3 | 50 | Heater |
| 4 | 50 | Heater |
| 9 | 30 | Four-wheel-drive module |
| 10 | 30 | CNG module switch, if equipped |
| 12 | 60 | ABS pump |
| 13 | 30 | Power passenger seat |
| 14 | 40 | ABS valves |
| 15 | 30 | Body control module, RP2 bus |
| 21 | 10 | Trailer reversing lamps |
| 22 | 10 | Four-wheel-drive system |
| 23 | 20 | Vehicle Power 1 |
| 24 | 20 | Vehicle Power 2, gasoline engine |
| 24 | 10 | Vehicle Power 2, diesel engine |
| 25 | 15 | Vehicle Power 3, gasoline engine |
| 25 | 10 | Vehicle Power 3, diesel engine |
| 26 | 20 | Vehicle Power 4 |
| 27 | 10 | Vehicle Power 5, gasoline engine |
| 27 | 20 | Vehicle Power 5, diesel engine |
| 29 | 15 | DEF tank heater, diesel |
| 30 | 15 | DEF line heater, diesel |
| 31 | 15 | Glow plug and dosing module, diesel |
| 34 | 20 | Heated rear seats |
| 36 | 30 | Heated and ventilated seat module |
| 37 | 5 | 24 V alternator, if equipped |
| 38 | 10 | PCM and TCM |
| 39 | 10 | ABS |
| 40 | 10 | Electric power steering |
| 41 | 10 | BLIS, trailer TPMS and rear CAN electronic module |
| 42 | 10 | Snowplow, if equipped |
| 43 | 15 | Interior fuse panel run/start feed |
| 45 | 15 | Heated steering wheel |
| 46 | 20 | Not used, spare fuse |
| 47 | 5 | Not used, spare fuse |
| 48 | 30 | Audio amplifier |
| 49 | 25 | Not used, spare fuse |
| 51 | 40 | Blower motor |
| 52 | – | Not used |
| 53 | 10 | Four-wheel-drive transfer case control module |
| 54 | 10 | Not used, spare fuse |
| 55 | 10 | Not used, spare fuse |
| 56 | 40 | Electric power steering |
| 57 | 20 | Trailer lighting module |
| 58 | 50 | Customer interface module |
| 59 | 60 | Inverter |
| 60 | 60 | Interior fuse panel B+ supply |
| 61 | 30 | Vehicle battery 2 |
| 62 | 5 | Smart Trailer Hitch |
| 63 | 10 | Smart Data Link Connector and Enhanced Central Gateway |
| 64 | 5 | Glow plug relay coil, diesel |
| 65 | 10 | CNG module power supply, if equipped |
| 74 | 30 | Trailer brake controller and auxiliary electric brake connection |
| 75 | 30 | Constant CNG power supply, if equipped |
| 76 | 25 | Trailer lighting module battery charging |
| 77 | 30 | Vehicle battery 1 |
| 78 | 20 | Power point 2 |
| 79 | 20 | Power point 1 |
| 84 | 20 | Horn |
| 85 | 40 | Heated rear window |
| 91 | 5 | Headlamp control module |
| 92 | 15 | Left headlamp |
| 93 | 15 | Right headlamp |
| 94 | 20 | Power point 3 |
| 95 | 20 | Power point 4 and Smart Charge module |
| 98 | 10 | Tailgate release |
| 101 | 50 | Customer interface module |
| 102 | 5 | Rain sensor |
| 103 | 30 | Front wiper motor |
| 105 | 30 | Fuel pump |
| 106 | 30 | Body control module, RP1 bus |
| 107 | 25 | Trailer parking lamps |
| 108 | 40 | Power driver seat |
| 109 | 30 | Starter |
| 111 | 30 | Power sliding rear window |
The 2023 P708 layout differs from previous Super Duty generations. For a related model in the same generation, see the 2023 Ford F-450 fuse box guide; do not assume that every circuit is identical between chassis variants.
Passenger compartment fuse panel
| Position | Amperage [A] | Protected circuit / function |
|---|---|---|
| 1 | 30 | Power windows |
| 2 | 30 | Power tailgate module |
| 3 | 30 | Passenger door module |
| 4 | 15 | Multicontour seats |
| 5 | – | Not used |
| 6 | – | Not used |
| 7 | 20 | Advanced driver assistance systems module |
| 8 | 10 | Delayed accessory power logic |
| 9 | – | Not used |
| 10 | – | Not used |
| 11 | 5 | Instrument cluster |
| 12 | – | Not used |
| 13 | 7.5 | Not used, spare fuse |
| 14 | 15 | SYNC |
| 15 | 5 | High-mounted center brake lamp camera |
| 16 | – | Not used |
| 17 | – | Not used |
| 18 | 10 | Radio transceiver module, four-wheel-drive switch and Enhanced Central Gateway |
| 19 | – | Not used |
| 20 | 5 | Power inverter |
| 21 | 5 | Upfitter/AUX switches |
| 22 | 10 | Auxiliary camera |
| 23 | – | Not used |
| 24 | 30 | Sunroof |
| 25 | 5 | Not used, spare fuse |
| 26 | 5 | Not used, spare fuse |
| 27 | 5 | Trailer brake controller switch |
| 28 | 5 | Auto-dimming rearview mirror |
| 29 | 5 | Heating, ventilation and air conditioning controls |
| 30 | – | Not used |
| 31 | – | Not used |
| 32 | – | Not used |
| 33 | 10 | Brake light switch |
| 34 | 7.5 | Steering column control module and instrument cluster |
| 35 | 5 | Heated rear seats |
| 36 | 7.5 | Manual gear selection, SelectShift |
| 37 | 5 | Head-up display |
| 38 | 7.5 | Telematics module |
| 39 | – | Not used |
| 40 | 10 | Left door switch and power telescoping mirror switch |
| 41 | 10 | Adjustable pedals |
| 42 | 5 | Central security module |
| 43 | 5 | Headlamps and ignition switch |
| 44 | 30 | Driver door module |
| 45 | 7.5 | Wireless charger and driver front seat module |
| 46 | 20 | Radio |
| 47 | – | Not used |
| 48 | – | Not used |
| 49 | 7.5 | SYNC display |
| 50 | 5 | Additional Smart Data Link connector |
| 51 | – | Not used |
Factory AUX / upfitter switches
Six factory AUX switches can power work equipment without tapping into the radio, lights or other existing cabin wiring. Each circuit has a dedicated factory fuse. The switch ratings and wire colors are shown below; verify the equipment installation before making connections.
| Switch | Fuse [A] | Wire color | Function |
|---|---|---|---|
| AUX 1 | 10 | Purple / green | Auxiliary circuit 1 |
| AUX 2 | 15 | Green / brown | Auxiliary circuit 2 |
| AUX 3 | 15 | Yellow | Auxiliary circuit 3 |
| AUX 4 | 10 | Brown | Auxiliary circuit 4 |
| AUX 5 | 5 | Blue / orange | Auxiliary circuit 5 |
| AUX 6 | 5 | Yellow / orange | Auxiliary circuit 6 |
Trailer, upfitter and incomplete-vehicle circuits
Separate Ford’s original wiring from circuits added by the body builder. In the under-hood box, position 57 supplies the trailer lighting module, 62 the Smart Trailer Hitch system, 74 the trailer brake controller, 76 the trailer lighting module battery charging circuit, and 107 the trailer parking lamps. A hydraulic pump, PTO-related accessory, winch or work light may have a separate fuse or breaker fitted by the conversion company.
For the previous model years, consult the 2020-2022 Ford F-550 fuse box and relay guide, which covers the earlier P558 wiring arrangement.
2023 Ford F-550 fuse box FAQ
Are all F-550 fuses contained in the two factory boxes?
Not necessarily. The factory under-hood box and passenger-side panel cover the original equipment, but a body builder may add separate fuse holders, relays or circuit breakers for its own systems.
Which fuses supply the electric trailer brake controller?
Under the hood, position 74 is the 30 A supply for the trailer brake controller and auxiliary electric brake connection. Interior position 27 is a 5 A fuse for the controller switch.
Why is fuse position 24 rated either 20 A or 10 A?
It depends on the engine: Ford specifies 20 A for gasoline models and 10 A for diesel models. Positions 25 and 27 also have engine-dependent ratings.
Does the 6.7 Power Stroke have separate DEF-related fuses?
Yes. Under-hood positions 29 and 30 protect DEF tank and line heaters, while positions 31 and 64 relate to glow-plug and dosing control. A blown fuse is only one possible cause of a DEF system fault.