Interior Lights on Trailer with No Battery Won't Work with Ford Truck

Question:

Hi, I am at a loss and was told that you guys might know the answer to this. I have a 2017 ford F350 king ranch FX4 with a tow package and a 2004 featerlite that does not require an in house battery. When I hook the trailer up, my truck tells me that the trailer is connected and all the outside lights on the trailer come on. However, when I tried to turn the load lights and the interior lights on in the trailer it doesnt work. the truck is brand new, the trailer is brand new, everything else works perfectly. Im told that this is a problem with ford because of the intelligent trailer connection. I have read in some forums that there is a pattern or sequence you can go through when you turn the vehicle on that will cause the lights in the interior to come on. Have you heard of this before and if so could you tell me how to turn these lights on? Thank you very much for your time All brake and markers lights works but the interior lights do not. the bulbs have tested to be good. What fuse numbers do i need to check or actions i need to take, thanks in advance.

asked by: Ben

Expert Reply:

The issue you're experiencing is caused by the Ford Smart Tow System which controls the battery charge line circuit which is the twelve volts power supply from the vehicle battery to the trailer. It's usually feed to an on-board battery in the trailer but in your case they are likely just powered directly from the power supply. To the best of my knowledge, the battery charge line circuit only becomes active while the truck is in motion so there is really no other way to get around this issue except for bypassing it and running your own power wire to the trailer connector from the truck battery with the 10 Gauge Wire part # DW02508-1 and 40 Amp Circuit Breaker part # 9510.

expert reply by: Conner L