On a 2013 F150, I have the tow package on my truck. I see in the relay box that I have the fuse for the electronic brake controller. However, I do not have the fuse for the Trailer tow battery charge relay power. Also there is only one prong in there so even if I put a fuse in there it won't go anywhere. On the aux power plug of the 7 prong adapter, I do not have any power. Is there a way to get power to that plug?

 

If you have the tow package w/ the trailer brake controller then the location for the trailer aux power should be active.(have both tabs) Are you the original owner? If not perhaps the previous owner installed the TBC and the truck wasn't equipped with the tow package. I bought my '13 new with the tow package and the fuse for the aux power was in a plastic bag in the glove box. I installed the fuse in the battery junction box and both tabs were there and I have power at the trailer plug. There should be no reason not to have both tabs in that location. There should also be a relay for the trailer aux power in the battery junction box as well. If you're looking at the box(under the hood), the row of relays closest to the windshield it is the 9th position counting from the passenger side. The fuse position should be #21.

 

I am not the original owner but I know them. I know they got the tow package because there is a transmission cooler. There is no brake controller. I had to go to the dealership and ask about that. Apparently, power is supposed to be supplied to the electronic brakes but I can't adjust it without the brake controller upgrade for $300+. When trying to diagnose this I did print off the entire fuses/relay section of the owners manual. I am positive (pun intended.. because it's off the positive post of the battery.. get it ) I'm looking at the correct one. I think I may end up going back to the dealership to ask. However, I find forums like this to be more helpful then the dealership typically. 18 year old high school kids working the counter typically don't know much but they can put in an inquiry to a tech at Ford.

 

If the truck was equipped with the tow package then there would be a brake controller installed. The trans cooler was an option depending on which engine you have, not necessarily related to the tow package. You can buy the brake controller and install it yourself. You would just have to activate it using a free program called Forscan and a ELM OBD II adapter. There is a whole thread on here about Forscan and it's usefulness. Here is a link to the brake controller. https://www.tascaparts.com/oem-parts...bC12Ni1nYXM%3D
Here is a link to the Forscan thread. Look at post #2817, there is a video posted detailing how to install the brake controller. https://www.f150forum.com/f38/forsca...9018/index282/
You should read through the thread, there is a lot of info in there about our trucks and how to do things without going to the dealer. Just as an example, I added the Ford OEM remote start just for the cost of 2 new keys that had the appropriate remote start buttons on them.

 

Ok I will take a look at installing the brake controller. $170 sounds much better than what the dealership was quoting me. Thank you for all that. However, lets say I don't have the tow package then. It did come with the factory equipped 7 prong trailer plug. How can I get power to the Aux pin then?

 

Does your dash transmission indicator include a "M".

 

Something did just occur to me though. The truck was in an accident, I'd be willing to bet that this wiring harness was replaced from a truck without the towing package.

 

Yes

 

One side of fuse #21 in the battery junction box is hot from the + side of the battery. The other side is supposed to go to pin #3 of the trailer tow relay. If you have no pin on the other side of fuse #21 then you'll need to run a jumper over to pin #3 of the relay. Pin #5 of the relay should have an orange wire on it, that goes to the 7 pin trailer plug. That's the wire that takes power to the plug. The last small relay all the way to the right in your pic is where the trailer tow relay is supposed to be. If you look under the BJB and there is an orange wire on pin #5 of the relay slot then you can take a fused 12v feed and jumper it to that pin and you'll have 12v at the trailer plug.

 

You my friend are nothing short of a genius if that works. How on Earth did you get such intimate knowledge of Ford's wiring?