Okay, this shows how bad I am with this stuff. I was under the impression that the box mounted in a harder to reach area and needed the extension harness for a more convenient location. My mistake. How do I fix the fubar order?So....you might have ordered TOO much!I know that's not a good thing to say as a business owner but.....
Typically, you only need one of the solutions: either the box OR the extension harness. Unless you're doing it for two trucks?
Who here has DIY'd your own Upfitter harness?
- OP 🔹 Ragin Cajun
- Start date
The box is mounted to the side of the upfitter relay box, then that will provide the connections to add accessories whenever you want. We provide pigtails with the matching connections:
Assuming you want the box, I can cancel the extension harness off. Just let me know and thanks again for the support!
- OP 🔹
- #24
- Feb 28, 2026
- 1,770
- 4,977
- Retired LEO
- 2025 F250 6.7 HO Platinum Tremor Agate Black
Awesome!
All set!
Link to order?
Ford Super Duty
A complete collection of Open Trail Creations products designed to fit Ford Super Duty trucks. This collection includes all compatible solutions across our lineup, making it easy to find products that are built for your vehicle.
www.opentrailcreations.com
Thanks again!
Really looking forward to seeing your finished product!
I went the route of adding a power distribution box behind the rear driver seat. I designed and printed a box that I could mount a 6-relay box to and included mounting points for all of the terminal blocks. I know the upfitters are rated to carry current but I felt better using them as relay triggers. This setup made it easy to run relay triggers from reverse lights, bed lights, etc. to the box and interface with the upfitter switches via the relays. I ran a 6 conductor wire bundle along with a 10awg positive and ground from the engine bay to the distribution box. I had enough left over so I ran another length of 6 conductor wire from the box to the back of the truck to use for aux lights, relay triggers, and such. It took some time to get everything wired up and working the way I envisioned but I'm happy with it. Unfortunately I don't have photos of the finished product but here's a mid-build shot.
True Mods Relay Box: https://www.amazon.com/dp/B0CDZCKBWM?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_11&th=1
16 Gauge 6 conductor Wire: https://www.amazon.com/dp/B0CL6MG9H5?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_15&th=1
I went the route of adding a power distribution box behind the rear driver seat. I designed and printed a box that I could mount a 6-relay box to and included mounting points for all of the terminal blocks. I know the upfitters are rated to carry current but I felt better using them as relay triggers. This setup made it easy to run relay triggers from reverse lights, bed lights, etc. to the box and interface with the upfitter switches via the relays. I ran a 6 conductor wire bundle along with a 10awg positive and ground from the engine bay to the distribution box. I had enough left over so I ran another length of 6 conductor wire from the box to the back of the truck to use for aux lights, relay triggers, and such. It took some time to get everything wired up and working the way I envisioned but I'm happy with it. Unfortunately I don't have photos of the finished product but here's a mid-build shot.
True Mods Relay Box: https://www.amazon.com/dp/B0CDZCKBWM?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_11&th=1
16 Gauge 6 conductor Wire: https://www.amazon.com/dp/B0CL6MG9H5?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_15&th=1
- OP 🔹
- #29
- Feb 28, 2026
- 1,770
- 4,977
- Retired LEO
- 2025 F250 6.7 HO Platinum Tremor Agate Black
Reach out if you have any questions!
After doing two low amp wires to the upfitters today, I understand the need for the Open Trails setup. I honestly didn’t prior. Its annoying to get out, and there’s no clean way to run harnesses up from the upfitters. I taped my BD harness and had a nice sheath (not that kind of sheath Optimus) on my Warn Harness but it still looks like garbage and now I have to pull it all apart again to do front lights or a compressor.
The OTC product and set-up is excellent. Why folks just don't buy his product and reinvent the wheel is beyond me. Very happy with mine and an easy install to boot.
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- OP 🔹
- #33
- Feb 28, 2026
- 1,770
- 4,977
- Retired LEO
- 2025 F250 6.7 HO Platinum Tremor Agate Black
Agreed. A lot cleaner than the monstrosity I built above. I hadn’t installed it yet, still recovering from surgery. But got me thinking that I may just order this and use my home built for spare parts.
Yeah, I wish I had found the OTC product before I installed everything. Luckily with the 7.3 I had plenty of room to make the connections.
Appreciate the support! Glad we could help!
I really appreciate the DIY’er approach. That has been my go-to most of my life. Building the harness is something I definitely would have done a few years back. Nice job 
I do find that I get older and have a bit more disposable income, I’m happy to pay for certain things rather than save $10 (and spend 100 hours building it myself
)
I got my OTC upfitter distribution block installed last week. So easy and so worth the small price! I highly recommend!
I do find that I get older and have a bit more disposable income, I’m happy to pay for certain things rather than save $10 (and spend 100 hours building it myself
)I got my OTC upfitter distribution block installed last week. So easy and so worth the small price! I highly recommend!
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Appreciate the support!I really appreciate the DIY’er approach. That has been my go-to most of my life. Building the harness is something I definitely would have done a few years back. Nice job
I do find that I get older and have a bit more disposable income, I’m happy to pay for certain things rather than save $10 (and spend 100 hours building it myself
I got my OTC upfitter distribution block installed last week. So easy and so worth the small price! I highly recommend!
Anyone install one without removing the factory upfitter switch box? I really don’t want to have to go through the hassle of pulling the battery if I don’t have to.
Who said you had to pull the battery???
