willalex09
Member
The purpose of this guide is to outline the process of retrofitting upfitter switches to control additional accessories, such as a roof light bar, rear lights, and a train horn. I wanted to add switches to the dead space above the sunglasses holder as I like the way switches look mounted above. I didn’t like any of the aftermarket options on Amazon as I felt they stuck out too much and looked “tacky”. Obviously, each to their own, this was just my personal preference.
This guide will cover the required materials, wiring modifications, and installation steps.
Required Materials
Wiring Modifications
Since these upfitter switches are designed for Super Duty trucks, they come with a plug intended for connection to the fuse box in those models, which is incompatible with an Expedition. Therefore, the first step is to modify the upfitter wiring by cutting off the fuse box connector and preparing the wires for this application.
Relay Block Wiring
The relay block consists of two wire bundles:
For ease of installation, I consolidated all ground wires into a single ring terminal and did the same for power and signal wires, allowing for a simpler connection to 12V power. This setup enables the switches to operate regardless of whether the vehicle is running or not. The signal wires can be connected to either constant or switched 12V power, depending on your preference. I think when installed in the super duties some switches only work when the truck is on and other work anytime, but don’t quote me on that lol.
After this, I had one ground connection, one 12V power connection, and four accessory output wires, one for each switch.
Installing the Switches
Extending and Routing the Wiring Harness
Extending the Switch Harness
I cut the switch wire harness about 12 inches from the relay block and soldered one end of the 8-conductor wire to the harness, taking care to match the colors correctly. Since the 8-conductor wire has different colors than the switch harness, keeping track of connections is essential. Then I ran the harness along the headliner, down the passenger A-pillar, behind the factory fuse box, and through the grommet into the engine bay. I already have two 0-Gauge power wires running through it for my sound system, so it was easy to follow the same path.
Illumination Wiring
For the switch illumination, I cut open the 8-conductor wire near the fuse block and extended the illumination wire from there to the back of the radio, then tapped into the radio illumination wire. This ensured that the switches light up and dim in sync with the rest of the vehicle's interior lights.
Mounting the Relay Block
Positioning the Relay Block
I decided to mount the relay block on the left side (looking at the truck) of the engine bay behind the battery. I drilled a hole and used a threaded insert to secure the box.
Final Wiring Connections
Once the switch harness is routed to the engine bay, I soldered the other end of the 8-conductor wire to the previously cut portion of the switch harness, ensuring the correct wire match-up. Finally, I connected the ground and 12V power wires to the battery and attached the wires from my accessories to the appropriate switches.
Final Thoughts
The whole process took me about 4-5 hours and 4-5 Irish Reds including breaks to play with the dogs. Overall, I’m very happy with the result. Since the switches are Ford OEM and along with the fact the switch lights illuminate and dim with all the other interior lights, make it look like it came from the factory this way.
This guide will cover the required materials, wiring modifications, and installation steps.
Required Materials
- Upfitter Auxiliary Cluster for 2011-2016 Super Duty Trucks (F-250, F-350, F-450): https://www.amazon.com/gp/product/B0885ZQPPC/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
- I picked this specific one because the 2011-2016 Super Duty models have interior lights that closely match the 2015-2017 Expeditions, ensuring the switch lights would match the rest of the interior lights.
- 18-Gauge 8-Conductor Electrical Wire: https://www.amazon.com/gp/product/B0CZL2YV9S/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1
- Additional wiring supplies such as 12-, 14-, and 16-gauge wire, connectors, solder, heat shrink tubing, etc.
Wiring Modifications
Since these upfitter switches are designed for Super Duty trucks, they come with a plug intended for connection to the fuse box in those models, which is incompatible with an Expedition. Therefore, the first step is to modify the upfitter wiring by cutting off the fuse box connector and preparing the wires for this application.
Relay Block Wiring
The relay block consists of two wire bundles:
- Power and Ground Bundle
- Black – 12V Power (Switch 1)
- Red – 12V Power (Switch 2)
- Green – Signal (Switch 1 & 2)
- Orange – Signal (Switch 3)
- Purple/Pink – Signal (Switch 4)
- Violet/Grey – Illumination (not used here, see below.)
- Accessory Output Bundle
- Blue – Output (Switch 1)
- Red – Output (Switch 2)
- Purple – Output (Switch 3)
- Brown – Output (Switch 4)
For ease of installation, I consolidated all ground wires into a single ring terminal and did the same for power and signal wires, allowing for a simpler connection to 12V power. This setup enables the switches to operate regardless of whether the vehicle is running or not. The signal wires can be connected to either constant or switched 12V power, depending on your preference. I think when installed in the super duties some switches only work when the truck is on and other work anytime, but don’t quote me on that lol.
After this, I had one ground connection, one 12V power connection, and four accessory output wires, one for each switch.
Installing the Switches
- Removing the Headliner
- I started by removing the weather stripping around the sunroof, followed by the interior light assembly. Once the assembly is removed, you can unscrew and slide out the plastic tray.
- Cutting the Mounting Hole
- Next, I carefully cut a hole in both the headliner and plastic tray, ensuring it was slightly smaller than the body of the switch for a snug fit. Once the hole is the correct size, the switches will slide in securely. The connector pigtail will protrude about an inch into the sunglass’s holder, though it will still function as intended.
Extending and Routing the Wiring Harness
Extending the Switch Harness
I cut the switch wire harness about 12 inches from the relay block and soldered one end of the 8-conductor wire to the harness, taking care to match the colors correctly. Since the 8-conductor wire has different colors than the switch harness, keeping track of connections is essential. Then I ran the harness along the headliner, down the passenger A-pillar, behind the factory fuse box, and through the grommet into the engine bay. I already have two 0-Gauge power wires running through it for my sound system, so it was easy to follow the same path.
Illumination Wiring
For the switch illumination, I cut open the 8-conductor wire near the fuse block and extended the illumination wire from there to the back of the radio, then tapped into the radio illumination wire. This ensured that the switches light up and dim in sync with the rest of the vehicle's interior lights.
Mounting the Relay Block
Positioning the Relay Block
I decided to mount the relay block on the left side (looking at the truck) of the engine bay behind the battery. I drilled a hole and used a threaded insert to secure the box.
Final Wiring Connections
Once the switch harness is routed to the engine bay, I soldered the other end of the 8-conductor wire to the previously cut portion of the switch harness, ensuring the correct wire match-up. Finally, I connected the ground and 12V power wires to the battery and attached the wires from my accessories to the appropriate switches.
Final Thoughts
The whole process took me about 4-5 hours and 4-5 Irish Reds including breaks to play with the dogs. Overall, I’m very happy with the result. Since the switches are Ford OEM and along with the fact the switch lights illuminate and dim with all the other interior lights, make it look like it came from the factory this way.
