OK i have an odd problem here and no clue where to go next.

I have a 2018 F350 with the tow package and the box and bumper plugs.
3 of my other buddies have the EXACT same setup, on same year truck. We all tow new travel trailers for a living.

My truck and JG truck when we plug in the trailer plug it will NOT work the electric jack, and the battery is not charging.

Frank and Steves truck WILL work the electric jack just by plugging in the trailer and will charge the battery
Like i said, exact same trucks. ALL batteries are tested and working fine.

If i plug in my 7 plug tester, and apply the brake, it shows i have 12v in both plugs (Box and bumper). Yet still not charging the batteries. And no matter what i do, if the battery is dead it will not work the electric jack.
This is the same on all trailers, which are all new from manufacturers.

I have been doing research and i have not seen anywhere that there is a fuse for anything like this i need to check, as it runs through the Electric Brake Controller. And, the oddest thing is it does show 12v at the battery and the cables that go to the battery on the trailer.

I'm seriously considering running a 12v key power to the 12v terminal on the plug, like it was with the other SD 16 and prior.

Suggestions??

 

I had this problem with my truck and RV. It was a lack of resistance in the circuit due to how the lights were controlled (ford sense resistance as a way to try to tell you if your trailer lights are working). I wired in some resistors. Curt sells a pigtail that does the same thing. If you're hauling rvs for a living I would get the pigtail. It's like 20-30bucks iirc.

 

https://www.curtmfg.com/part/57003

???????

But why is it 2 trucks do work properly and 2 do not? Wouldn't it be easier to just run a wire of 12v key on to the 12 volt battery charge pin?

 

Sorry don't know. Others with the same rv / same truck didn't seem to have this problem but I did. The resistors fixed it for me so I stopped investigating at that point.

 

I would go the resistor way if you gave me info on it.

 

 

I'm sorry, I don't have a answer for you, but I do have a question.

Why do new trailers have dead batteries?

​​​​​It may be such a large draw, the trailer BCM module may think it's a dead short. Have you seen a Ford dealer, if so what have they said?

On one of our trucks, we have a hundred gallon transfer tank that I have a plug that goes into the bumper plug. It will not supply power until is cycled through brake, and gear

 

If anyone else wants to do it, here are the instructions. I will try it asap and advise.

 

I added these to my trailer, one for each turn signal.

https://shop.advanceautoparts.com/p/...bx2/11137849-p

Unfortunately not a good solution if you're pulling many different trailers.

 

I moved a trailer the other day and experienced the same thing. I set the parking brake, put the truck in neutral and itstarted charging. Apparently, mine does not charge in park.

 

New campers do not come from the factory with batteries, they are supplied by the dealer. Pullers carry a battery to put in place to provide break-away power for the brakes. It's also handy for running a power tongue jack, if present.
I'll often back up to a camper and simply plug in the umbilical in order to operate the tongue jack or landing gear as these are invariably too low to get under as they sit. Often, I'll lift the jack, back under the ball, turn off the truck and get out to lower the ball; suddenly remembering that I now have no power to the tongue jack because I turned the truck off.

@JohnnyGaloshes - when you connect to the camper, is your truck recognizing a trailer is connected? Mine will indicate a trailer is connected and indicate whether the lights are working correctly or not. I have found it is not necessary to select a trailer (such as default) unless I want to track miles. If I don't select a trailer no mileage is recorded.
If the truck indicates a trailer is connected and no trailer is selected, then everything should be working. Again, the truck must be running for this to work. Also, as I am pulling the camper out of it's slot, I let off the gas and squeeze the brake over ride to ensure the trailer brakes are working. It's then that the display indicates the brakes are set to eight.
As to why your truck is not working, I have read of one case where the truck's plug was wired incorrectly at the factory (or the connector was wired incorrectly by the manufacturer). Otherwise, I have found that some umbilical connectors do not fit very well (usually on very inexpensive campers) - they don't have a positive click to lock into place and can be twisted from side to side. Last week I had a camper that - 30 miles into the run - had a failed right turn signal. I stopped at the first rest area and checked - sure enough it wasn't working. I twisted the connector from side to side and it started working. About another 40 miles or so the left turn signal quit working. Twisting the connecter side to side cured that as well. The problems did not return the rest of the run. I've observed other strange behavior when the umbilical is not plugged in quite right - such as the power tongue jack clicking but not going up or down.
Before changing anything on the truck, I'd try to connect to a camper again, paying close attention to the umbilical connection to ensure it is inserted completely and that your plug and the umbilical plug don't have any bent pins.

 

 

Ford engineers don't seem to have much faith in our ability to operate lights and power outlets without killing the batteries.

 

If i hook it up to have 12v while accessory on won't it overcharge the battery?

 

I am an ignorant bystander.

But, I think I've read several related threads here.

Here is one. I'll try and post several more today:

https://www.ford-trucks.com/forums/1542845-extra-battery-charging-question.html