2004 F250 Diesel 6.0 trailer relay wiring diagram

[jodeb720]

Evening gents,

my buddy has a 2004 f250. He bought it used and never towed with it.
His father recently purchased a 5th wheel and has told him he's able to borrow it.

Fast forward, and I put my 7 pin tester in the hitch and there's no turn signals or brakes (flashers) coming out of it.
I'm getting 12volts for the battery connection and the clearance lites only. I've not tested the trailer brake controller - yet. At least I wanted to get the turn signals and brake lights working.

I've chased the wiring to the fuse block under the dash, and the fuses are good.

I put a phone toner on one of the wires and found there's a trailer relay box under the hood. In it there are 4 relays and one 10 amp fuse - but there are three spots for fuses. The manual doesn't say anything about the wiring in the trailer fuse relay box.

Does anybody know anything about the wiring in this fuse box?
It may be the relays in the fuse box are shot, but without being able to chase the signals from the fuse box inside to the relays, I'm shooting in the dark.

Any help would be very greatly appreciated.

Thanks so much!

Josh

[jodeb720]

Bedlam,

Thanks for the reply. You hit the nail on the head.
The factory Trailer Relay box is located under the hood - and when I opened the box, there's four (4) relay's and one 10 amp fuse - which I tested and it's good; However there are also two (2) additional fuse locations.

I went through the manual, twice, and I can't find any documentation for it.

Mitch gave me the online version and I went through them as well, and I can't seem to find any docs.

I've found the wiring diagram - which I can go through (eventually) but it would be much easier if the manual had notes on the fuses. It could be something as simple as missing the two fuses - but at what amperage?

What about the relays? I could test them as well -

Thanks!

Josh



FactoryTrailerRelayLocation

[Bedlam]

There is second fuse box under the hood in addition to the one under the dash. It is square blue or pink fuse.

[jodeb720]

Thanks Mitch!
Hopefully this will have something that the OE manual didn't have in it.

[MitchF150]

Go here and enter the vehicle info for your Ford vehicle and it'll have a PDF owners manual for you.

https://owner.ford.com/tools/account/how-tos/owner-manuals.html

It'll have all the fuse/relay info in it.

Mitch