Hello,
As a longtime reader and 3rd time F150 owner, I appreciate all that this community has done to help me understand, fix, and customize my trucks - thank you!

I'm having a strange issue with my 2019 Lariat and thought I would see if anyone has experienced similar; my searches haven't found an answer. And, before someone states the obvious, no I haven't tested a new battery yet - I will soon and will post the results, if any.

I changed out most of the exterior lighting on the truck (headlights, tail lights, 3rd brake light). Immediately after I changed out the 3rd brake light, my keyless entry became very finicky. Again, this happened immediately, like a switch being turned off. Now, even when sitting in truck, it says key not found.

The truck is a couple months old. Again, I will try a new battery, but wondered if anyone has experienced something similar.

Thanks,
Neil

 

Sounds like something else is going on. What happens when you put the 3rd brake light back to factory? It might be a load issue.

 

It's very likely your switch over to LED bulbs. If the bulbs are not properly shielded, and cheap bulbs are not, they can cause rfi interference when they are on that blocks the sensing between the keyfob and the vehicle fob sensing antennas.

 

I believe there is at least one thread discussing this issue. The OP changed the HMSL (High Mounted Stop Lamp) back to the original condition and the problem went away. Not sure what would be the best way to search for this, but it is at least a month or two old. Not sure if anyone figured out the actual cause.

 

I haven't tried yet - will give it a shot when I have some time. Thank you

 

Good point, and thank you for the reply - maybe I'll try shielding the whole back side of the unit, if the factory swap back fixes things. Will post results when I get to it.

Thanks

 

I think I found it, https://www.f150forum.com/f83/2018-r...4/#post6444450

I posted there, asking if he made any progress. Thank you!

 

It's rfi from the LED bulbs. My F-150 doesn't do it, but the LED tail lights I put in my Corvette interfere with opening my trunk until the lights go out.

 

Thanks. Would a ferrite coil resolve the issue in this case? Assuming, of course, that the wires are carrying the RFI from the guilty LED or driver?

 

I've seen references to them working but have no firsthand experience.