Troubleshooting No 12V Power on 2017 Ford F-350 7-Way Connector

Updated 03/27/2026 | Published 12/23/2017

Question:

2017 Ford F-350 platinum 6.7 Dually with 5th wheel prep and camper package. No 12 volt charge power in truck 7 way plug receptacle. Testing with a meter. All other lights work fine. dealer said no mods needed, should work fine. Tested with engine on, and touched the brake also. Ford manual say trailer has to be connected to truck , truck will see connection and after that I need to touch the brakes to send power to the 12 volts power charge line. How can I test 12 volt truck pin, with trailer plugged in? How can I test the 12 v power line? Thanks

asked by: Victor

Expert Reply:

If you aren't receiving any power at the 12V pin location on your truck's 7-Way connector, I recommend making sure that there is not a blown or missing fuse. I took a look at the online owner's manual for your 2017 Ford F-350 for the related fuse and relay locations. Check to make sure the 30 amp fuse in the 27 position and the relay in the number 37 position are present and in good condition. These are located in the power distribution box in the engine compartment and are specifically for the trailer tow battery charge circuit.

You can test the 12V pin on the truck side connector by using a circuit tester like # PTW2993. If you are not receiving power at the 12V pin, and all the necessary fuses and relays are present, I recommend tracing the power wire back and checking for any damaged or exposed areas, fixing as needed. You can test the wire every so often along its length to see if you can find a dead spot.

If you still cannot locate and resolve the issue, please let me know and I will be happy to look into this further.

expert reply by: Chris R