Trailer battery not charging, see manual.

[BruiserNL]

Good day everyone. On my 2022 f150 every time I plug in my 7-pin trailer and start the truck I get the message stating trailer battery not charging, see manual. The only way I seem to be able to get this to work is to start the truck, get out and unplug and replug the seven pin every single time that the truck is restarted. I have tested the pins at the back with a voltmeter and I also test inside the trailer at the bus bar. Nine times out of 10 I never get power to the battery for recharge, once in awhile it will start without this message and power is going to the back.

I have had it into the dealer they can't seem to find anything wrong. It's so frustrating that every time I start up I get this message. Quite often even when no trailer is connected I will be prompted to select a trailer. Quite often with no trailer connected and I put my truck in reverse I will get the message reverse brake assist not available.

Stuck for what to try next.

Has anyone found a fix for this? I see lots with similar faults.

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[MrGary321]

I had a similar issue. Interior lights on my horse trailer were left on, which resulted in a heavy current draw and no charging along with the same message that you had. I recharged the trailer battery fully. Message eventually disappeared and battery remains charged. I never figured out its logic.

 

[powerboatr]

a few things
what type of trailer, is it a camper or flat bed etc.
as above
charge the trailer battery fully
if you have a break away battery, make sure its charged as well, and in sound condition. it will play havoc on the system error messages.
what
then re-check your GROUNDS on trailer wiring through the 7 pin for soundness of connection and ground path
grounds, or lack of are the devils workshop with our trailer systems in the truck
and give the rest of wiring a good look over for issues, like bulbs not working etc and or loose connections
lastly, can you borrow another similar truck to check the trailer and see if it trips same messages

 

[BruiserNL]

a few things
what type of trailer, is it a camper or flat bed etc.
as above
charge the trailer battery fully
if you have a break away battery, make sure its charged as well, and in sound condition. it will play havoc on the system error messages.
what
then re-check your GROUNDS on trailer wiring through the 7 pin for soundness of connection and ground path
grounds, or lack of are the devils workshop with our trailer systems in the truck
and give the rest of wiring a good look over for issues, like bulbs not working etc and or loose connections
lastly, can you borrow another similar truck to check the trailer and see if it trips same messages

Thanks for the reply. I have a newer cargo trailer and its the emergency brake break away battery that I am referring to. I have tried two different batteries and both have been charged to 100%.

There does not seem to be a ground issue. When I check the power at the + and - terminals inside the trailer I get a very low reading, 0.3 volts, until I leave the truck running and unplug and replug the 7 pin. Works every time and goes up to 14 volts. Only on a very rare occasion does it work right the first time the truck is started. If I was on a long road trip and stop multiple times for fuel/snacks/rest, etc... I would have to start the truck, get out and remove and insert the 7 pin in order to get power to the trailer.each and every time. No way is this normal.

I have yet to have the chance to hook a similar truck to my trailer, but my trailer has been on other trucks (Not Ford) without any message. Maybe they just do not offer these messages.

What is also added to this mix is the intermittent REVERSE BRAKE ASSIST messages when no trailer is attached, and sometimes SELECT A TRAILER message when nothing is connected. I feel the 7 pin or harness has an issue.

Ford has tried to hard to make these trucks smart, that the trucks are now outsmarting the technicians. My truck has had so many electrical issues it's not even funny.

 

[powerboatr]

reverse brake assist adds a layer
if you turn that off does it still misbehave? there was a re flash thing or whatever on some trucks. mine was done as part of some thing when i took delivery, in fact they couldn't activate my ESP until it was performed, i am sure maybe your dealer checked that ????

the voltage coming up after you unplug and then plug back in is an indication the truck is LOOSING communication with the trailer. its a sensitive thing
LED lights have also caused issues with low current draw, but that was addressed in programing but again anything is possible
can you tell truck to do the light check via ford pass to ensure its talking to each other?

checking it against another same model truck would be helpful, maybe your dealer can pull one off the lot and do a quick test

there is also some issues with the 7 pin connector in the bumper not being fully seated with the truck harness connectors.
it can drive you bat crap crazy easy.
i spent nearly a week chasing trailer disconnected, no light, light, trailer connected etc
it was a bad breakaway battery and wiring
and i had to run grounds off the led lights right to the frame, vice allowing light mount bolts to serve as ground.

good luck

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