2019 F250 XL 6.2L extended cab

after plugging in trailer, marker lights on truck do not work. If I turn the light dial to always in, they then on for a second and then diminish. I have running lights but no marker lights and rear tail lights only come on with brake application and then signals. I checked the trailer tow light fuses and 99.

can someone recommend what other fuse would tie into the marker lights, or something else I can check, ford dealership cannot look at it for a week.

 

Welcome to the site..

The market light power distribution comes through and is controlled by an integrated park lamp micro processor within the Body Control Module. The rear parking, side lamps, license lamp share a spliced connection with the marker circuit out by the right headlamp/inner fender area. The grounding for the markers and other lamps varies depending on cab profile. For EC i believe the circuit ground is in the left interior rear cab pillar. Fuse F50 50amp supplies power distribution for the BCM which the module then supplies output for the lamps..

If I read your complaint right, the markers and others come ON and then slowly dim (?) meaning all the lamps noted above follow the same issue, correct?

If the lamps come on and fade out or drop out, I’d doubt it would be a fuse since more features would likely fail. Possibly a ground, harness issue, or even an issue with the BCM

 

Thanks for the reply, the marker lights come on for a half second and then diminish. From 100% to 0%