Upfitter Switch
Logistics Pro
Joined: Mar 2019
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I believe they are behind the passenger kick panel and in the engine bay.
Junior User
Joined: Feb 2019
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They are wired and powered under the driver's side hood hinge (below fuse block), If you want to run switched power to the inside of your truck, you simply find one of those same wires and connect it to (run a wire to) one of the "pass through" wires in the cab. The pass through wires are under the passenger side hood hinge ( near fire wall) and come out behind the passenger side kick panel next to your right foot.
Senior User
Joined: Jun 2017
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I did not know about the pass-through wires on the passenger side mentioned below but that’s great to know too.
Senior User
Joined: Jun 2017
Posts: 121
Likes: 1
yes, they are hot/switched and connected to the upfitter switches already. They can be spliced/found near the driver side firewall under the hood. They also have ignition keyed and always-hot wires included in the bundle. All are labeled and there’s a PDF floating around this forum with the schematics too.
I did not know about the pass-through wires on the passenger side mentioned below but that’s great to know too.
https://www.ford-trucks.com/forums/1...al-source.html
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From: Fairbanks, AK
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4wd Low
Joined: Jun 2020
Posts: 13
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From: Conway, AR
yes, they are hot/switched and connected to the upfitter switches already. They can be spliced/found near the driver side firewall under the hood. They also have ignition keyed and always-hot wires included in the bundle. All are labeled and there’s a PDF floating around this forum with the schematics too.
I did not know about the pass-through wires on the passenger side mentioned below but that’s great to know too.
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Laughing Gas
Joined: Mar 2008
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Yes, the wires under the hood, under the upfitter relay box are already hot. The color codes match up to the switch number.
If you want to power something inside the cab, use the pass through wires provided.
If you want to power something inside the cab, use the pass through wires provided.
4wd Low
Joined: Jun 2020
Posts: 13
Likes: 2
From: Conway, AR
Ah, I misread it. Though you were referring to inside the cab. I can't find the pass through wires. There are a hundred videos on YouTube and none that clearly show where the pass through wires are located under the hood. About to remove the battery since that's one option. 2021 F-350.
Fleet Mechanic
Joined: Nov 2015
Posts: 1,670
Likes: 668
From: DeMotte, IN
Mine (2023 F350) are under the upfitter relay/fuse box all taped up. Found them after I removed the battery box that a 2033 Ford document said they were located under. The Ford body build document is a good resource though I find discrepancies in that also.
4wd Low
Joined: Jun 2020
Posts: 13
Likes: 2
From: Conway, AR
I spent two hours looking and gave up. Ford was no help.
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