My 2016 F-250 diesel lariat started acting weird a couple weeks back. When I tried to start the engine with my remote key in the ignition the engine did not turn over. I released the key and tried multiple times, no engine turn over. I checked, cleaned battery posts and cables on the 2 batteries under the hood. I replaced the battery in my key fob even tho the original battery tested over 3 volts. Still acting up and may or may not turn over engine. When I tried starting engine with factory key fob from outside my truck the engine did not turn over and the truck horn honked 1 time. Now one time I try starting the engine it may turn over & start then the next time the engine may not turn over at all. This truck is 4 plus years old and has 16,000 miles on it.
The body control module controls those functions.
You mentioned a key fob and then a factory key fob. Do you have an aftermarket key fob as well? Did you install an aftermarket remote start kit?
Is your problem the engine fails to crank — that rr rrr rrrr sound with the key in “start”. Or is it a cranks ok, but doesn’t catch and run?