Rmeyer

My 2015 f150 with no trailer hooked up on dash display states trailer light problem what can I check

smokeywren

First thing I would do is test the circuits in the 7-pin trailer plug on the back of the tow vehicle. You can buy a circuit tester at almost any RV store, then keep it in the toolbox in the trailer for future testing. Here's one:
https://www.etrailer.com/Accessories...y/TR20117.html

Steve Osborne

Any novelty toys....
Addded backup lights or extra lights using trailer hitch wiring