Troubleshooting 2017 Ford F-250 Error Message for Trailer Lighting Module

Question:

I have a Cedar Creek 38FLX fifth wheel with LED tail lights. When trailer is hooked up to 7 way on my 2017 F 250 7 way plug and turn left blinker on I get a Left turn fault showing. Should I install resistors to turn signal and brake light wiring to resolve?

asked by: Michael B

Expert Reply:

In order to help you troubleshoot this issue I need to ask you a few questions.

On the trailer, do the turn signals operate properly, meaning do they flash at the expected rate?
Were the LEDs installed recently as replacements or are they the original OEM lights?
Has the trailer operated correctly until now or has it always had this issue?

I ask these questions because the newer Fords have a fairly complicated trailer wiring setup and I have heard of this issue before. Sometimes the cause can be as simple as some trapped water or dirt in the vehicle 7-way socket, or in the connector that plugs into the rear of that socket. A bent electrical contact within the vehicle socket or trailer plug could also lead the truck's trailer wiring system to think there is a problem when there isn't. If that one trailer light has a bad ground that too could cause the error message.

That's why I ask if the trailer's exterior lights work. If the trailer turn lights operate as they should then the error message could just be an annoying quirk related to the truck's electronics.

Load resistors are sometimes needed to correct for hyper-flashing of LED lights when they are used in a turn signal application but this is usually the case only when LEDs are installed in place of standard incandescent bulbs. The low power draw from LEDs can "fool" wiring systems into thinking a bulb has blown out and this can trigger error messages.

If the trailer turn lights are working correctly I would not be concerned.

expert reply by: Adam R