Trailer Battery Not Charging

[gspete]

I just hooked up my trailer and the 7 pin trailer plug is apparently not charging the trailer battery. Also, The interior lights on the trailer do not work as the trailer is not getting power as expected. All fuses are in place, as far as I can tell, and the fuses all test good.

I did have a trailer company say that someone needed to be in the driver's seat for power to flow to the trailer battery and lighting. I put my wife in the seat and that did not seem to work. Also, the trailer company said that a fuse may have been blown but they all seem to be in place and test good.

All other lights work just fine on the trailer.

Any thoughts on what to check next?

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[uavmx]

My trailer has a battery disconnect that needs to be on for anything to work from the 7 pin. If it's not that I would mutimeter the pins coming from the truck to see if power is being produced.

 

[gspete]

My trailer has a battery disconnect that needs to be on for anything to work from the 7 pin. If it's not that I would mutimeter the pins coming from the truck to see if power is being produced.

Thanks, I will look into that.

 

[daemonic3]

My trailer has a battery disconnect that needs to be on for anything to work from the 7 pin. If it's not that I would mutimeter the pins coming from the truck to see if power is being produced.

Yep. It should kill everything past the electronic tongue jack (if you have one) so you can still hitch up. Try operating the tongue jack, and if you have a voltmeter the battery hopefully is just under 13V if not charging, and over 13V if charging (connected to 7-pin).

 

[gspete]

Well, I just left Ford with both my truck and trailer. They cannot figure why the "Trailer Battery Not Charging" error dialogue appears on the dash. They hooked up to their computers and spoke with a couple of guys and cannot figure why this message is appearing.

I guess I will lose my truck for a while they try to figure out this problem.

 

[gspete]

The dealer has told me that this is a new problem with 2021. There is no battery voltage coming from the trailer and make sure the 12-volt source was connected on the trailer side.

I was a bit skeptical but I went to a local trailer shop and hooked up to a couple of trailers and sure enough, this error message went away and the interior lights started working as well. I took the cover off of the trailer wiring junction box and the 12-Volt source from the trailer is not connected. I have not connected it yet but fairly sure this will address the problem.

 

[F150Eh]

The dealer has told me that this is a new problem with 2021. There is no battery voltage coming from the trailer and make sure the 12-volt source was connected on the trailer side.

I was a bit skeptical but I went to a local trailer shop and hooked up to a couple of trailers and sure enough, this error message went away and the interior lights started working as well. I took the cover off of the trailer wiring junction box and the 12-Volt source from the trailer is not connected. I have not connected it yet but fairly sure this will address the problem.

Sorry, just wanted to clarify - was the issue with the trailer and not the 7-pin connector from the truck, or Ford changed the wiring in the connector and modifications to the trailer junction box need to be made to enable battery charging for the 12v source?

 

[gspete]

Sorry, just wanted to clarify - was the issue with the trailer and not the 7-pin connector from the truck, or Ford changed the wiring in the connector and modifications to the trailer junction box need to be made to enable battery charging for the 12v source?

The issue is with the trailer. Ford went through the wiring on the truck for the trailer and all is correct. I know a guy who has done this and it has fixed the issue.

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