for anyone wondering if you can program a previously programmed key fob, the answer is yes,
i was able to program a third spare remote access fob that was used (from ebay) it had already been programmed, (even had the cut key inside)
also the ford website AND owners manual for the F150 is wrong! use the mustang method as mentioned in post #45
similar to the post above...

 

glad to have found this forum and the experiences of other f150 owners... got a deal on a new fob on amazon and was worried when i found few 2018 owners making a 3rd (spare) fob for the just in case situation... but following the directions of jack-b-quick in post #49 got the new fob FULLY functional after trying other methods that did not work... my truck was one with the slot under the console cup holder... with buttons facing forward in the slot and moving quickly through the process - SUCCESS!!!!
thanks to all !!!!!

forscan here i come...

 

I'm trying to add a new key fob with remote start and tailgate options,(mine does not have these options)I followed the procedure above, and the lights flashed and the horn honked.
but the fob does not work at all, I attempted to re-do the procedure but I get a max number of admin keys or something like that.
when I check under mykey it says I have 4 admin keys and no mykeys.
can the admin keys be deleted or reset?

 

Does anybody know how to delete or remove a 3rd Intelligent access Key(push button start) I have all 3 keys but am wanting to remove 1 of them. I have forscan if needed.

 

Hey guys, I don’t have any key fob slot under the cup holder. I have a bench seat in the front with a middle 3rd seat. I have two fobs that work in rough condition and ordered a 3rd and don’t know how to program it at all. Anyone can give me step by step instructions on how to program the 3rd and show me where the key fob slot is would be much appreciated. Thank you

 

There should be a 'slot' of some kind for the IA FOB. It is where you put the FOB to start the truck when the FOB battery is bad. Check your owner's manual. Since '15 was the first of the 13th gen, it could be different. Just guessing.

 

Just programmed a key using instructions in this thread, thanks. Easy peasy.
FYI, in my 2019 the slot is in the front-most cup holder and I inserted the fobs with button facing rearward. I have heard that the slot is in the other cup holder sometimes so don't know if it impacts key orientation.