I have a '09 f-150 FX4 flareside with tow pkg and integrated brake controller. In the 7 pin plug, I do not have any 12v power at the + pin. All other features (turn, stop etc) work. I tried looking for a fuse, but nothing in the manual jumps out that says trailer battery power. There are two slots for trailer battery charger, but they are empty--put a fuse in those two slots, but still no power. Shouldn't this + pin always have power, whether the ignition is on or off? I called the dealer, told them they should have checked everything out--shame on me for not checking myself -they would not give me a simple starting point that I could check before making a appointment to bring it in--I picked up the truck 9/1/09. thanks for your help---

 

There should be a 30amp fuse in position 21 and relay in position 9 of the battery junction box under the hood. The dealer may not have installed them.

The fuse will be hot all the time and the relay is powered during start/run only.

 

BJB ( aka Battery Junction Box, Engine Compartment fuse panel ) Fuse # 21 is the fuse, and the relay is also in the BJB, relay 9.
BJB fuse #54 is the trailer tow coil fuse, but looks like it has other items on it, and should already be installed.

These are hot in start or run key positions only.

In previous years, some of the items for the trailer tow adapter were in a bag in the glove box, to be installed by the owner.

Check those 2 fuses and the relay, and put the key in the run position prior to testing with a meter.

 

thanks for all the help--did not realize fuse and relay had to be in at the same time--there is also a relay #4 that says "heated backlite relay" . Is this for the rear window defroster---I have a power slider, so I don't think I need this. Again, thanks for all the help.

 

That would be the rear window defroster. I would need to check if this is jsut the rear window, or also the mirrors.

 

thanks--I have a laser temp gun, so I will also check to see if there is or is not a temp increase when I turn on the mirror heaters.

 

Took a look, the relay also controls the heated mirrors on the sides





A relay is only like 20.00 at Autozone, just get a new one if the plastic bag was not in the glove box.

 

found out with the heated mirrors being removed from the circuit--I had no indicator light on the switch for my mirrors when I put the switch on -- my truck was a locate, so the bag may have been removed from the previous dealer or person who had taken it for a test drive. Still, thanks for all the info and diagrams -- I printed them out to put in my folder on the truck -- have a safe and happy new year