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Troubleshooting Lack of 12V Power at 7-Way Trailer Connector on 2019 Ford F-150  


The 12 volt #4 is not hot on my F250 2019. I looked in the owners manual and does not clearly specify which fuse it is. Yes I tested it when the. The truck was running. Thanks


Expert Reply:

Since you are not getting the 12V power when your truck is running, you most likely don't have a fuse issue as you stated their isn't a specified fuse or relay in the owners manual. The issue is that your truck is computerized even at the 7-way. It can sense when a trailer is connected based on the voltage draw so it won't sent a signal for 12V when using some testers, especially LED testers because there isn't enough of a power draw.

The system requires a power draw on the 7-way and then holding the brake pedal for about 3 seconds until your dash registers "trailer connected". At that point, the vehicle will deliver the 12V power to your trailer connector and not before. I recommend using a circuit tester like # PTW2993 to test for the 12V power once you get that "trailer connected" message on the dash. That 12V power will be on the 1 o'clock pin location on the 7-way so the corresponding wire will need to be probed to test.

expert reply by:
Jason S
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I have both a 2017 and a 2019 F150 that I want to tow my 2019 Jeep Wrangler JL with. I have installed the Mopar K6862742 factory wiring harness to flat tow the Jeep. When I plug the Jeep into a Dodge Ram 1500 all of the lights workbrake, signal, clearance When I plug the jeep into either of my F150’s nothing works.................I thought all 7 way plugs were universalThanks

Chris R.


The specific pin function locations on a standard 7-Way are universal, so I'm not exactly sure why the harness isn't working on your F-150 trucks. It would be odd for both to have a blown fuse - but it wouldn't hurt to start there. You might also test the 7-Ways with a circuit tester just to be sure everything is working on the truck's end. Do you have the ignition on in the F-150 when testing the lights?



@Lee The Mopar harness uses the +12v from the 7way connector to switch a relay that connects the tow vehicle signals to the JL lights. No +12 and it doesn't work. Seems the Ford needs to sense to a load on the 7 way before it supplies +12 to the 7 way connector. Mine works on a 2019 Ram but not my 2017 F550 motorhome.

Jason S.


Jason S Your etrailer trouble shooting tips are well value your team has been very help full and knowledgeable Thank you etrailer for being out there
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Harley W.


Lee is correct. And they are NOT universal. My Dodge 2500 is different from my F150. Power and Ground are the same but Left, Right, Tail and Backup are all mixed up. Ford claims they conform to a SAE standard. I'm thinking I'll need some sort of converter/translator to use with one of the trucks! Grrrrr.... AND Ford has built in a whole raft of conditionals to make a trailer connection; all of which are enforced by the accursed Body Control Module. Bureaucracy on four wheels!

Les T.


Like Lee, I have a trailer I pull with 2 different trucks. I have a 2012 F350 I pull a travel trailer, and also at time pull a lowboy with. The lowboy, I use a 7-way plug, 4 wired because my lowboy does not have brakes.. No issues at all with the travel trailer or lowboy lights. All work fine... on the F350 I also have a 2019 F150, and when I plug the lowboy into it, only running lights work. No blinkers or brake lights... weird.... I'll check and see if mine is the same as Harley W's...

Etrailer Expert

Chris R.


I'm pretty sure the F-150 just has a blown fuse under the hood. Check your owner's manual for the appropriate fuse locations tied to the trailer turn/brake lights and replace them to see if that resolves the issue.

Les T.


@ChrisR I searched the manual and found the fuse for the lights. Pulled, and it is fine. Went ahead and even replaced it. Still no go.. SOOO I went ahead and bought a MICTUNING 7 Way Blade Trailer Connector Tester with Red LEDs. Everything works great on my F350. Does not work on my 2008 OR 2019 F 150's..... No blinkers or brake..... More digging to do.....
Etrailer Expert

Chris R.


@LesT Hmmm. I wonder if it's just an issue with the factory wiring. Try and test the wires behind the connector to see if you get any power there. If you do - then the connector itself is bad and just needs to be replaced. If not - I think it might be worth it take a trip up to a local Ford dealer to have them take a look.
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