I have a 1 month old 2021 Platinum and the front side marker lights do not work. To be honest I don't know if they worked when I bought the truck because it is barely noticeably to me. However, I went to install after-market side vent LED's and I noticed they were not working. Both sides are inop. All other lights on the truck work fine, especially the front amber light (thin/horizontal). I hooked up my LEDS and they work great. Is there a fuse or relay for the side marker lights? I would take it to the dealer but since I messed with the harness they are going to say it is not covered.

Please note I started on the drivers side first and that is when I noticed both side marker lights were inop. The new LED hot is spliced to pin3 and the ground is spliced to pin 10 on each side.

Thank you.

 

If your headlights look like this, I believe that's just a reflector on the side with no marker light built-in.

 

It does look like the light you have pictured. However, I am pretty sure it has a light in it. I will take a look at other trucks to verify. I have attached a diagram from another website. My after-market LEDs are attached to pins 3 and 10 and they work just fine.

2021 F-150 headlight wiring diagram

 

doesn't appear to be a light in the diagram for any 'side marker light'....