What are the aux switches for in the Ford?
Ford's auxiliary switches are a bank of four factory-installed switches that let you power and control aftermarket or upfitted equipment—such as lights, a winch, or an air compressor—without modifying the main wiring harness.
These switches are part of Ford's upfit capability on many trucks and SUVs, typically wired to dedicated fused circuits and controlled through the vehicle's body control module. The exact behavior and fuse ratings vary by model and year, but the bank usually provides ignition-switched power and an organized way to add electrical accessories while protecting the rest of the electrical system.
Where you’ll find and how they’re wired
The auxiliary switch bank is typically located in the overhead area behind the rearview mirror in many Ford Super Duty and F-Series trucks, or integrated into the overhead console in newer F-150 trims. The four switches feed four separate circuits, each protected by a fuse and routed to a common power source, usually the battery through a relay controlled by the switch bank. The wiring harness is designed for common 12V accessories and is intended for easy upfitting by dealers or aftermarket installers.
Common uses for the switches
Owners use the four switches to control aftermarket electrical equipment added during factory upfits or by aftermarket installers. The bank makes it simple to add power to items without splicing into the main harness.
- Off-road and auxiliary lighting, such as LED light bars, spotlights, flood lights, and rock lights
- Winch operation for recovery or helper towing
- Onboard air compressor for tires, tools, and air tools
- Other accessories, including portable refrigerators, small in-vehicle power inverters, or extra 12V outlets
These four circuits are designed to handle common 12V loads used by trucks and SUVs. Check your vehicle's manual for exact fuse values and load limits for each switch.
Model and year variations
The availability and placement of the aux switch bank vary by model and year. In many F-Series trucks (F-150 and Super Duty), the four switches are part of an Upfitter Switch Bank installed by a dealer or included with certain trim packages; in other models or trims the bank may be optional or require an upfit kit. Always consult your owner's manual or dealer for the exact wiring and fuse configuration for your year and trim.
Installation tips and safety considerations
Follow best practices to use the auxiliary switch bank safely and effectively. The steps below are general guidelines for owners adding or using these circuits.
- Identify the load and ensure it matches the switch's indicated amperage and the fuse rating.
- Route wiring away from heat sources, sharp edges, and moving parts; use proper grommets and protective sleeves where needed.
- Use the provided fuse and relay arrangements; never bypass fuses or run heavy loads without proper protection.
- Test each circuit with ignition on and off, verify correct behavior, and regularly inspect wiring for wear or corrosion.
Proper installation and adherence to load limits help protect your vehicle’s electrical system and maintain warranty coverage where applicable.
Summary
Ford’s auxiliary switch bank is a convenient, factory-provided set of four switches that control dedicated circuits for aftermarket equipment. Common uses include lighting, a winch, an onboard air compressor, and other 12V accessories. Availability and exact wiring vary by model and year, so consult your manual or dealer for specifics. When used correctly with appropriate fusing and routing, the aux switches offer a clean, safe way to expand a vehicle’s electrical capabilities while keeping the main systems protected.
