I can not figure out how to get my interior lights of my trailer to work when plugged in to the 7 way trailer connector, I have tried activating the cargo light, having parking lights on, ignition on.

Called the dealer and they had no clue either, they just want to blame the trailer, but I think possibly the connector does not have the correct power, I recall years ago when I had a checvrolet, that it did not come with the fuse installed for the trailer connector.

Truck is a 2018 Lariat F150, Max trailer tow pkg.

Thanks in advance for any help.

 

Did you confirm the interior lights were connected to the truck 12vdc supply? Generally that hot wire is only to maintain voltage on a battery for brake.marker lights and emergency breakaway. There was another thread if you search where the guy put a small 12 volt battery in the trailer for interior lights. A garden tractor battery will do.

 

Too add ....the other posts...
is the trailer programmed/added to the list of trailers you may have
key on / truck running... doors closed...
some still posting. Needing to cycle brake pedal to activate the 7 pin...
park / running lights on.

 

I need to leave the fob in the truck for the interior light to work. Has to be in truck from when it is started. Once fob is taken out, lights dont work until restarted with fob in truck..

 

X2 what the above 2 posts said. Next years model you'll need to rub your stomach and pat your head also <winks>

 

And possibly when the driver's door is opened the 12v is switched off. It's way too complicated now to get 12v to the battery/trailer.

So basically, it'll never work without a battery attached.

 

This is for a 19 F250. May answer your question. Good info for myself and brother also.

https://www.etrailer.com/question-336052.html

______________________________
19 F150 Max Tow.

 

You can rewire your trailer so that the interior light is wired into the running lights circuit...then the interior light will work whenever the running lights are on. Just make sure your interior light is on a switch so you can turn it off if you don't need it (like driving at night with your vehicle lights one).

Another solution is to run a dedicated 12V line to the back of the tow vehicle and use that for interior trailer light(s).

 

Ford has a better idea for sure!
Both my brother and I have newer Ford F150 trucks and cargo trailers that have interior lights that took a long time to figure out how they worked. Tried the trailer sales where I bought the trailer from, two Ford dealers and online, had the trailer rewired because they built it with those electrical scotch lock connectors that fail after a few days, months or years, but never are good for any wiring that is exposed to a corrosive environment or constant vibration. But never got an answer why or how to get the interior lights to work. Not any of those people knew anything that would work or even where to start. I even contacted the trailer manufacture to get a wiring diagram of the trailer. then went to a RV trailer dealer to see if they could get the interior lights to work and they got them to work but when I hooked up the truck they would not work. The way they checked the lights was to connect the trailer up to a 12 volt power source so the truck system was not even in the system when tested. It seems to me like Ford Motors should have something in their owners manual that explains this problem and how to get the lights to work.
By the way if you have these Scotch lock connectors on your trailer, get rid of them and use soldier joints with shrink tube that has sealing compound in them instead, they will almost never fail. The shrink tube seals out the moisture and they never corrode the connections. The trailer manufacturer even used the scotch lock connecters on the brake wiring. l found that the only way to get those lights to work was: You must have the truck running with the key or key fob inside the truck and you need to apply the brakes for a second and let off then get out of the truck and close the door.
This seems like the stupidest thing any engineer could come up with. Why would you want to be working inside your trailer and have it running so some criminal could get into your truck and drive away with your truck and trailer plus anything in the trailer. I do understand why they want to avoid running the truck battery down if you would leave the interior trailer lights on for an extended time or overnight.
But I am sure their are much better solutions than this one out there.
Seems like these engineers that designed this system must never have had a trailer before. Why could it not be done like the truck lights do and go off after a few minutes if you leave them on for an extended time.

 

For power to the interior of the trailer, come off pin 3 hot, pin 7 ground of the plugin connectror.
This powers the running lights on the trailer when they are turned on.
For secondary power, use a battery but you need to keep it charged.
A single pole double throw center off switch can be used to select either power source through fuses, for safety.
Pay attention to the amount of curent the lighting will need and use LED lights for min. current draw.
Anything more such as a night time long term supply and 120 volt needs AC wireing added, outlets, lights and the use of a power generator. Same as what is used at night at a race track or other venue.
Nothing complicated about all this.
Good luck.