2019 F-350 conFUSEion

[orbsah]

Hi all - I have a couple questions regarding a towing fuse on my truck. A couple weeks ago I saw Mark from KYD mention he was missing a 30A fuse that's supposed to go into slot #27 in his F-450 fuse box. Curious, I checked out my fuse box and sure enough, there's no fuse in what I think is slot #27 . But this got more confusing because the fuse box in my truck doesn't match the fuse box drawing in my owners manual. The manual clearly shows 8 fuse slots along that rear edge of the fuse box yet mine only has 7. So a few questions. . . .
1. What exactly is that #27 30A fuse for?
2. Which slot is it in my fuse box?
3. Why did Ford not include this?

Hopefully the images help explain. . . .

Thanks, -Jeff

[orbsah]

Oops, I should have used the search function first. . . .
https://www.mygrandrv.com/forum/show...844#post132844

https://www.mygrandrv.com/forum/show...201#post232201

(Still a little confused though)

[DaveMatthewsBand]

You’d have better luck on the F-450 forum since maybe only 5% of us run that tow vehicle.


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[cfowler55]

It’s not uncommon for the trailer charge circuit to need a fuse and/or relay to be functional as delivered from the factory. I’ll try to remember to look at a fuse box diagram in my shop software tomorrow and report back here.
Charlie

[CoChris]

@orbsah, if you have the factory builtin trailer brake controller (TBC), I do not think you need the fuse (on a 2017 and newer Super Duty). If you have an older Ford (which you do not) or it did not come from the factory with the TBC, then you would need the fuse. Be aware that Ford has gotten very "smart" with the trailer "hot/charge" circuit. It is only active in certain conditions, and they do not all behave the same. In general, to activate the trailer hot/charge pin on your 7 way connector you need to have the truck running, have the trailer electrical cord connected and then step on the brakes (some same for a couple of seconds) before the circuit is active.

Chris

[Txfivver]

As CoChris stated, Ford stopped using the relay under the hood that you have to insert to make the trailer charge wire go hot with the 2017 and up Super Duties. Both my 2019 F350 and the new 2020 F450 only require you plug in the trailer and step on the brakes or simply drive away for it to start charging the trailer batteries.

[orbsah]

Thanks for the info everyone. Now I'm curious why Mark thought he needed to add it for his 2020 F-450.