Ford F 150 with no hot wire to TT?

[RoadrunnerII]

Only other thing to try is configure the trailer in the setup menu for the truck if you havent already. Make sure you hold your foot on brake when you shift out of park into drive. Leave in drive for 30 seconds to a minute then test for voltage change on tt battery. If the TT battery is full charged it wont try to charge it either. Run battery down a bit see if it comes back up. Whats your volt meter reading on TT Battery before hooking up truck?

RoadrunnerII

[ALJO]

RoadrunnerII: If the TT battery is full charged it wont try to charge it either.


But there should be still power on Batt.+ from the 7 pole outlet of the truck.

[RoadrunnerII]

New trucks won't put 12 volt on the charge pin unless they see the load for thevelectric brakes. Easiest way to validate the charge wire has voltage is see if the voltage on the battery goes up. Battery needs to be slightly discharged. Run the jack up and down twice should pull it down part of a volt. Saves pulling the 7 pin apart

RoadrunnerII

[GrumpyDad]

Originally Posted by RoadrunnerII

New trucks won't put 12 volt on the charge pin unless they see the load for thevelectric brakes. Easiest way to validate the charge wire has voltage is see if the voltage on the battery goes up. Battery needs to be slightly discharged. Run the jack up and down twice should pull it down part of a volt. Saves pulling the 7 pin apart

RoadrunnerII

agree, this is easiest way to test. Just putting a voltage meter on the 7-way connector of the truck doesn't work with the newer "smart" trucks.
Truck needs to be running as well.

[Scott91370]

I hate the way the new F150s are with the charge circuit. I'm not sure if mine works or not but have't found a way to test it.
Trailer is named and everything else on the trailer that is 12v (including brakes) work. I have done everything mentioned in this thread to get it to charge but after driving 6 hours the voltage does seem to drop - I bought an electric volt meter that plugs into the TV 12V outlet so I can monitor it better now.
Down size is that the wire on the truck for 12V charging is only 18g so it's not going to be able to do much.

[RoadrunnerII]

Only alternative is a seperate wire run from battery on truck with a relay tied into ignition circuit, fuse and heavy gauge wire and disconnect the ford version at 7 pin on truck. Smarts on truck likely wont know the difference.
Just a thought if you want to ensure you charge trailer batteries on road. Not sure if the alternator will be big enough. Should be but......

RoadrunnerII

Originally Posted by Scott91370

I hate the way the new F150s are with the charge circuit. I'm not sure if mine works or not but have't found a way to test it.
Trailer is named and everything else on the trailer that is 12v (including brakes) work. I have done everything mentioned in this thread to get it to charge but after driving 6 hours the voltage does seem to drop - I bought an electric volt meter that plugs into the TV 12V outlet so I can monitor it better now.
Down size is that the wire on the truck for 12V charging is only 18g so it's not going to be able to do much.

[Scott91370]

I have thought about doing the relay and heavier wiring. Alternator should be ok to charge, it doesn't lose that much voltage but on my long trips I need to be able to use the battery to run the heater when I make my stop at night and would like to start off with a full charge. And even if it took 10 hours to recharge the next day I'd still be on the road so it could take its time.

[TWP723]

Originally Posted by Chet & Marie

Thanks Midnight. Will try in the AM. What do I do if no trailer shows up?

Verify the BJB fuse 35 (20A) is OK. With all do respect, there are a lot of things that can affect your lights. Body Control Module (BCM) for one. Trailer module for another. The breaker in the junction box would be the cheapest of all of them. But the trailer electrics travel through more than just relays and fuses. My suggestion is to pay the diagnostic fee and find out. But check #35 first. Good luck.

[Nunzo]

My truck came with a 30 amp fuse that needed installed for the plug who charge the coach batteries. Under hood install -and it worked great.

[RoadrunnerII]

2014 and newer went to a smart system No fuse under hood any more

RoadrunnerII

Originally Posted by Nunzo

My truck came with a 30 amp fuse that needed installed for the plug who charge the coach batteries. Under hood install -and it worked great.

[jpurvis]

Don’t know about Ford, about to years ago had same problem with Chevy. Turns out the wire that ran to the plug assembly was not connected to the fuse box. Just coiled up at the firewall.

[sinnott4]

Do you have 12V from post 5 to 2 (Ground), if not the problem is in the truck and probably a fuse. If you have power to post 5 then the problem is in the trailer or wiring harness. I have a Jayco Hummingbird and had a hard time finding the main fuse, it was hidden under the front of the trailer.


George Sinnott
2018 Jayco Hummingbird
Chrysler Pacifica

[Atlee]

Incorrect about the 2014.

It may have changed when Ford went to the redesigned aluminum body in 2015.

I bought a new 2014. It came with a trailer fuse wrapped up and located in the glove box. I had to install it under the hood to make the 7 pt trailer receptacle "live".

Originally Posted by RoadrunnerII

2014 and newer went to a smart system No fuse under hood any more

RoadrunnerII

[RoadrunnerII]

Originally Posted by Atlee

Incorrect about the 2014.

It may have changed when Ford went to the redesigned aluminum body in 2015.

I bought a new 2014. It came with a trailer fuse wrapped up and located in the glove box. I had to install it under the hood to make the 7 pt trailer receptacle "live".

My bad I meant after 2014 model year.
With the 2015 model redesign Ford went to the smart system that no longer has the fuse and relay that dealer or customer found in glove box and installed. The fuse slot is there under the hood but is NOT enabled or listed in owners manual. Power to the charge pin is enabled when the truck engine is on, senses electric brakes, brake pedal depressed and shifted into drive It then applies power to the trailer 7 pin connector battery charge line. It may take 30 seconds or so to go live.
Once live you can then shift to park engine still running and the pin will still be live provided the trailer battery is not fully charged.

RoadrunnerII

[MoeA]

I have a 2012 Ford F150 that had the 12v charging fuse and relay in a bag in the door when I bought it. I thought nothing of it until I realized my trailer was not charging during towing. Once I installed the relay and fuse the trailer now charges while towing. Here is a quick info location: https://www.etrailer.com/question-188098.html

[Chet & Marie]

Decided this was a dealer issue so taking it and TT to ford dealer.

[Scott91370]

Tuck or Trailer dealer?

Let us know the outcome.

[Chet & Marie]

Truck Dealer.

[Scott91370]

Wow, not sure why I didn't see that in your original post. Still look forward to the diagnosis and fix.