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Hey guy, so I have a 2022 f650 with the factory installed switches. Under the drivers side dash I find the 6 switch wires, and in the engine compartment I find the 16 pass through wires. On older models, even 2021 the pass through wires in the Body Builder wiring diagram shows them ending up also under the drivers dash right next to the 6 Upfitter wires and then just need to be spliced together.

On the 2022 it’s different, the pass through wires come through the firewall and disappear under the dash, they terminate somewhere.

so my question is I’m trying to install a front and back light bar and I don’tknow what wires I need to connect to in the engine bay as I’m not sure which ones go to the switch. I’ve called 4 dealerships and no one can help.
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I worked on a couple of these an upfitter had trouble getting PTO operation to function correctly. If my memory serves me right, there are no "pass-through" circuits provided on the 17-22 medium duty trucks. I did peruse the wiring diagrams and confirmed this. Mind you, the medium duty trucks can be strange when it comes to wiring and electronics so if I have one of these trucks on the lot, I will take a look firsthand and get back to you. Also, the manuals and wiring diagrams can sometimes lag behind or have inaccuracies. Your third picture shows the blunt cut upfitter switch output circuits from the relays under the dash on the driver's side. For wiring to the outside of the truck you will need to fabricate your own pass-though. If this is indeed necessary, I recommend drilling a new hole in the firewall with a rubber grommet installed before running your fabricated harness through. I do see 6 blunt cut wires your truck should only have 4 upfitter switches so I cannot account for the white/blue and brown/white wires... The other pics are for the PTO control and SEIC.

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I worked on a couple of these an upfitter had trouble getting PTO operation to function correctly. If my memory serves me right, there are no "pass-through" circuits provided on the 17-22 medium duty trucks. I did peruse the wiring diagrams and confirmed this. Mind you, the medium duty trucks can be strange when it comes to wiring and electronics so if I have one of these trucks on the lot, I will take a look firsthand and get back to you. Also, the manuals and wiring diagrams can sometimes lag behind or have inaccuracies. Your third picture shows the blunt cut upfitter switch output circuits from the relays under the dash on the driver's side. For wiring to the outside of the truck you will need to fabricate your own pass-though. If this is indeed necessary, I recommend drilling a new hole in the firewall with a rubber grommet installed before running your fabricated harness through. I do see 6 blunt cut wires your truck should only have 4 upfitter switches so I cannot account for the white/blue and brown/white wires... The other pics are for the PTO control and SEIC.

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Thanks I ran a new wire through yesterday. It can be very frustrating trying to figure out the wiring in these trucks. The 2021 body builder wiring diagram shows pass through wires underneath the drivers door well right next to the 6 Upfitter switch wires, but the 2023 diagram doesn’t show any there. I gave up and ran my own. Thanks for the reply.
 
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