Upfitter/pass thru wire screw up argh

[DMays]

On my 2020 the wires all were correct according to the owners book. Big issue I had was how short they were. Made for a tough time to make a clean setup for sure. Btw be careful not to overload the fuse for switch 1 and 2. I blew one and it was a pain to find and not cheap for what it is.

 

[FINRPTR]

I found the wires under the dash taped to another harness, they are looped a couple times. when you get them straightened out, they are actually very long. My issue is they all have no power, all 6 underhood wires have power. The Ford wiring manual does not show the under dash wires anywhere, nor does it show where they connect to the relays. I tried hooking up my Ford scan tool to see if a parameter needed to be reset or something like that, no help. I also cleared all the codes, no help. I believe the wires are spliced at the relays, but I really don't want to tear the truck apart to find out. Has anyone run in to this situation, power under the hood on all 6 wires, but no power under the dash?

 

[onthebrake]

There is 2 sets of wires. One set is powered and connected to the upfitter switches. The other set is just the pass through wires. Both sets of wires are in the lower kick panel of the passenger side.

 

[FINRPTR]

Please explain "pass through" does this mean they have ends under the hood with nothing attached? If this is the case, where under the hood are the other ends?

The upfitter switch wires do not power up directly from the switch, the power comes out of the relay, activated by the switch. Right?

 

[FINRPTR]

And if there are upfitter sw powered wires under the dash passenger side, I cannot find them. I have been out there for hours, multiple days and still can't find them.

 

[onthebrake]

They are not under the dash. They are in the lower kick panel on the passenger side. Pretty much right at the carpet line. Remove that little panel and you'll find them.

 

[MAMiller44]

@FINRPTR These other replies are kinda half answered.

In the cab, on the right of the front passenger footwell where the interior fuse box is you’ll have one set of wires. These are the pass thru wires.

In the engine bay right in front of the firewall and kinda behind the main fuse box, you’ll have TWO identical bundles of wires right next to each other. One of these sets are powered via the aux switches and what you want to connect accessories to. You need to figure out which bundle is hot by turning an aux switch on and finding the one with 12v.

The other set is the other end of the pass thru wires. These are just the other end of those ones you found on the interior. They intentionally have no power and are not connected at either end. The intent behind these is if you want to use the aux switches for something inside the cab. Just connect one of the pass-thru wires in the engine bay to the corresponding hot aux wire right next to it, and bam, now you have an aux connection in the cab.

 

[FINRPTR]

MAMiller44,

This information was extremely helpful. Thank you very much for providing, clear concise information on this subject. I used this information to run wiring out to the bed of my truck for some cage lights. I used an upfitter switch, the switched wires under the hood, connected one of the pass throughs to get power inside, then ran the wires out the back of the cab. I would still be messing around with all of this if not for your valuable information.

Thanks again.

MODERATORS, THE INFO PROVIDED BY MAMiller44 SHOULD BE A STICKY NOTE!!