How to Activate 12V Trailer Power Circuit on 2017 Ford F-350 Super Duty

Updated 02/26/2018 | Published 02/23/2018

Question:

I have a 2017 Ford F-350 super duty that the dealer installed the hitch system and wiring for a factory trailer hitch kit includes TPMS and rear backup camera and wiring loom after receiving the truck from the factory. I tow a 2016 DRV Mobile Suites 39foot 5th wheel RV with the truck. I have suspected that the trailer was not receiving the 12 volt charging from the truck. I purchased a Tekonsha N6562 Trailer Emulator to test the 7-way plug and found that the 12 volt pin was the only one not working all the others tested correctly. The Ford dealer has on two occasions in the past week said that it worked okay and to test it on my trailer as that would activate the module, whatever that means. However, the shop formans own trailer emulator showed that same result when he plugged it into my trucks 7-way trailer plug. Is there something I’m missing in this situation? Thanks

asked by: Bernie Z

Expert Reply:

Ford service bulletin SSM 46257 for the 2017 F-350 indicates that the vehicles equipped with a factory trailer brake controller (TBC) utilize a trailer module (TRM) which initiates the trailer 12V charging system.

For trailer charging circuit to operate, the TRM must detect a trailer is connected and a brake pedal input before charging power will be present at the trailer connector. Some trailer simulator products may not work correctly in all situations so connect your trailer, apply the brake pedal then test the 12V circuit's contact with a circuit tester like # PTW2993 to verify that the 12V trailer charging circuit has been activated.

expert reply by: Adam R