The trailer wiring harness isn't working on my dads '09 xlt. I think it has to with the trailer shorting out, which is another issue. First I need to get the truck working, and I'll fix the trailer after. The question is, what fuse/relay would cause this, and if it's not those what else could it be? Fusable link?

 

There are no fusable links listed for the '04-08 so I doubt the '09 has 1 either. You say the wiring harness isn't working- what does that mean? Does nothing on the plug work at all? I assume he has already been towing with it so the stuff in the bag in the door cavity has been installed. There are 5 fuses listed in that system and 4 relays so we need to know a little more details about what exactly the history is and EXACTLY what is not working and when it stopped, if it did work. I know they changed a LOT of things on the '09 but I don't know if they changed anything in the towing wiring or not.

 

Have you checked the owners manual, starting on page 316?

BJB ( Battery Junction Box / engine compartment fuse panel )

Fuse #6 - Trailer tow park lamp relay
Fuse #31 - Trailer tow park lamp relay
Fuse #37 - Trailer tow left hand stop/turn relay
Fuse #38 - Trailer tow right hand stop/turn relay
Fuse #45 - Trailer tow stop turn relay feed

If that is not good enough, here is the 2009 EVTM on the trailer tow adapter

 

Thanks guys. Turns out it was a fuse under the hood. I remeber doing it in my '06 and I am almost sure it was in the cab fuse box. Btw, those are some different looking fuses, like a mini fuse with no prongs, just the sides are exposed.

 

The 09+ MY went back to the 2 fuse panel payout like the 97-03 MYs.

The SJB ( Smart Junction Box ) has a lot more in it than just fuses, and the space could not hold everything is what I am guessing, thus back to 2 fuse boxes.

 

They're called "low profile ATM" fuses.

 

Missed that completely

The one on the left ?

 

You've got it.

 

On my 06 I lost trailer towing or running lights. Still have brake lights and turn signals left and right. And I still have electric brakes working. Just lost the running lights. I looked in the manual and couldnt find a fuse for the trailer lights. Just a relay. Anyone know if it has a fuse and what number it is?

 

Trailer Tow Parking lamps, Fuse #10.
Same one for the trailer tow reversing / backup lamps

 

Now there's something that needs to be "standardized"!. There's no reason in the world to have all those different fuse shapes, is there? On our recent trip into Colorado and Utah, we arrived a Rocky Mountain National Park to discover that the trailer charging fuse in my truck had blown. This is a 30 AMP "cartridge" style fuse. Kind of a big sucker that you can't pull with a fuse puller - I needed a pair of slip joint pliers).

I went into the nearby town of Estes Park, and at the only two automotive stores, no one had an "exact" match. I've forgotten now what the correct designation is, but I finally bought a PAL mini 30A female terminal fuse (they have "maxi" ones too), and it worked fine for the remainder of the trip. Of course I haven't a clue why the original blew, pretty hard to troubleshoot one time events.

But, why oh why are there so many different fuse styles? A small parts outlet can't possibly stock them all. I DO understand the need for different Amp ratings and that some need to be "slow blow" and others "quick acting", but all those different shapes?

- Jack

 

Thanks for the help sscully. I will go out and check that right now.