Trailer light problems on '09 F-150 ford

Good evening people. I am adding trailer brakes to my 2009 F-150 truck so I can have brakes on both axles of my new trailer to haul my tractor on now. I have run into a problem that has me sorta stumped. The truck does not have a factory towing package so I have had to add the brake controller and all wiring to it. I got that installed and am using a 7 way RV type plug on both the trailer and the truck. The truck already has a factory flat 4 way trailer light plug just left of the center of the rear bumper. I installed a class 3 hitch on the truck and I am using a 7 pin RV connector unit at the rear of the truck . The 7 pin unit has an adapter that you plug into the flat 4 pin connector for the lights. Now for the problem. With everything connected up I only have power to the tail lights on the trailer,no turn nor stop lights. Tail light power at 4 way flat and 7 pin RV connection good , ground is to the frame of the truck and shows less than 1 ohm resistance on the meter when checked. All functions good on the truck. I checked the wiring and connections as far as I could follow them above and past the spare tire on the left side rail. It doesn't appear to have any current for those lights coming to the plug from the front of the truck. Went on line and checked around and the suggestions seemed to say that there are a couple of relays or something in the fuse box that has to be installed. Any body have any idea about this. This is my first Ford since about 1967 model year and I need rescuing if possible. The Ford dealer here only has a couple of guys that can change oil and maybe put on a tire but nothing serious. This is aggravating and I want to get it finished up. Thanks in advance for help.
Gene Davis Tennille, Ga.

I believe the factory trailer plug has it's own fuses, separate from the truck lights.

Look at the owners manual or look it up online. There are fuses under the hood and under the dash. Be sure you are looking at the right fuse panel.

Steve @ Ad. has it nailed if it is like my 06. Mine was plug and play as most wiring was in truck. I had to get special loom from brake controller manufacturer that plugged in under dash. Wiring was to rear of left frame rail to a plug connector where 4 lead flat connector plugged in. Ford made a 6 or 7 lead harness to replace the 4 wire unit that plugs in there. I had to add a breaker in the fuse box for 12 volt feed for brake away brake battery charging / camper interior lights ect. and I believe a fuse for brake controller. Wiring harness was in truck just not with end details needed for towing package.

I sure hope you come up with the answer. I have a '02 F 150 with a left turn signal trailer light won't light up that I can't find the problem. On my P/U there's two fuses under the hood, a fuse for each side, we're talking break & hazard lights, and one under the dash that works for both. I don't have power coming into the plug at the back of the truck, all lights on the P/U work as they should. Good luck finding the problem.

A neighbor's Ford has the trailer fuses in a box inside cab behind the kick panel below the glove box.

Your Owner's Manual (if it is still with your truck) should have the same info as the website the link below is from. Run through the fuses and relays under the hood to be sure they are all there. As others have posted you may need a short harness for the brake controller and another to connect the socket to the truck wiring at the rear. In case you don't have the manual here is the link to that website with the index of the fuse boxes.

https://www.startmycar.com/ford/f-150/info/fusebox/2009

Wayne,

As discussed (a few days ago) in your post on Tractor Tales about your problem. If all the relays and fuses are in place and good under the hood, you need to start at the terminal for left turn on the socket and chase that wire back until you find power on it. You may have a bad connection in a plug in harness connector, corrosion in a connector, or a broken wire, that feeds just the trailer socket. It maybe up under the rear of the bed or along the frame. You may end up chasing the wire all the way back to the box on the fender well. Just looking at fuses and relays won't solve your problem. Hands on, under the truck, chasing the wire back is the only way to find it that I can see you can solve your problem. Been there, done that many times.

This post was edited by Jim.ME on 10/20/2021 at 01:16 pm.

My truck is a 2010 so may be different but the only fuse for the 7 pin plug that was not installed was the fuse to supply twelve volts to the center pin (I think) to charge a battery on my travel trailer. It was in the glove box.

Well folks the mystery is solved about the missing power for the stop and turn signal trailer lights on my 2009 F-150 Ford. Since it did not have the factory towing package kit on it when bought new there is a fuse and 2 relays in the fuse box under the hood that have to be installed to activate the circuits. These are supposedly included in a small plastic bag in the glove box when new but since I bought the truck used they were not there. Installed them and all is well for now. These lights are fused separately from the truck lights that do the same thing.Thanks for the help!

Gene Davis Tennille, Ga.

(quoted from post at 14:57:05 10/21/21) Well folks the mystery is solved about the missing power for the stop and turn signal trailer lights on my 2009 F-150 Ford. Since it did not have the factory towing package kit on it when bought new there is a fuse and 2 relays in the fuse box under the hood that have to be installed to activate the circuits. These are supposedly included in a small plastic bag in the glove box when new but since I bought the truck used they were not there. Installed them and all is well for now. These lights are fused separately from the truck lights that do the same thing.Thanks for the help!

Gene Davis Tennille, Ga.

Click to expand...

The 12 volt live fuse & relay wasn't even installed in my MaxTow Package truck...new in bag in glove box.