Hey Guys I have a 2007 F150 STX
I am trying to program a after market replacement transponder key

I have two working keys, One factory and one locksmith bought.
but they both start the truck.

I have attempted this several times and for some reason it wont work.

I put original key in and hold for a few seconds usually long enough for the security light to stop blinking.
i then remove the 1st key and put in teh 2nd store bought key and do the same put it to run and keep untill the light stps blinking < usually 3-4 blinks>

i then remove that key and put in the new key and turn it to run. the security light never stops blinking.
i turn it to off and try starting the truck and nothing just a constant security light blink.

i have done it that way and the hold the key to run for a count of 1 and two and still nothing

both other keys work. but i cant get the new one to what am i doing wrong

 

You need 2 original keys to do your own programming. Your locksmith key is probably just a clone of the other key you have.

 

so i need to take this one to a locksmith too? i thought if you had two woring keys you were ok

 

Yep, the locksmith is going to have to clone one of them. To do your own programming, you have to have the 2 original keys or clones of them. The system is seeing your 2nd key as the same as the first one, and that doesn't work.