What do the aux switches on F350 do?
They provide factory-provisioned, switch-controlled 12V power for aftermarket equipment, with each switch governing a distinct circuit that you can toggle from the cab.
In more detail, the auxiliary switch bank on many Ford F-350 models is a built-in set of switches designed to simplify powering add-on accessories. The exact number of switches and which circuits they control can vary by model year and trim, but the general idea is consistent: each switch sends 12V power to a dedicated circuit through its own fuse or relay path. This helps owners install equipment such as lighting, winches, air compressors, or fridges without running custom wiring from the battery to a random switch.
What the auxiliary switch bank is and where to find it
Location and layout
On many Ford Super Duty trucks, the aux switch panel is a dedicated bank of toggles integrated into the dash/center stack area. The switches are typically labeled AUX 1 through AUX 6 (or AUX 7 on some configurations). Exact placement and the number of switches can vary by year and trim, so consult your owner's manual or a build sheet for your specific vehicle.
Typical electrical characteristics
Each switch typically controls a separate 12V circuit via an integrated fuse/relay arrangement. While ratings can differ by model year, a common expectation is roughly 20A per circuit, with the total available amperage limited by the vehicle’s electrical system and the harness. Always verify the exact specifications for your truck in the manual or Ford's official documentation.
Owners commonly use the aux switch bank for accessories that benefit from a ready-made, switch-controlled power source. The following uses illustrate typical practices; exact circuits and recommended devices depend on your year/model and the factory wiring harness.
- Aux 1 – Exterior lighting (bumper lights, fogs, or a front light bar).
- Aux 2 – Additional lighting (roof lights or rear lighting).
- Aux 3 – Winch power supply (often via a relay and proper wiring to a winch battery or mount).
- Aux 4 – Air compressor or air suspension components.
- Aux 5 – 12V accessory power (fridge, inverter, or auxiliary outlets).
- Aux 6 – Miscellaneous lighting or power needs (antenna lights, scene lighting, etc.).
Note: The exact mapping of AUX switches to circuits and devices varies by year and trim. Always confirm with the owner’s manual or a dealer installation guide for your specific F-350 configuration.
Using the auxiliary switches effectively requires some best practices to protect the electrical system and ensure reliable performance.
- Identify each circuit’s rated load and attach only accessories that stay within that limit.
- Use proper relays and fuses as recommended for each accessory; don’t power high-current devices directly from a switch without a relay.
- Group high-draw devices on separate AUX circuits to avoid overloading a single circuit.
- Install proper wiring gauge and secure connections to prevent heat buildup or corrosion.
- Consult the manual or a qualified technician if you plan to run multiple high-load devices simultaneously.
Proper planning and adherence to electrical ratings help prevent battery drain, wiring overheating, and potential damage to the vehicle’s electrical system.
The auxiliary switch bank on the Ford F-350 is a built-in, six- (or seven-) switch system designed to power aftermarket 12V accessories through dedicated, fused circuits. It offers a convenient way to run lights, winches, air compressors, and other gear from the cab while keeping wiring organized and safer than DIY splices. Always verify the exact circuit mappings and ratings for your specific year and trim, and follow safe wiring practices or seek professional installation for high-current devices.
