Why does the yellow light come on when I program the first key but doesn't come on for the second key?

Question

During programming when I put in the second key only the blue and red light come on and stay on.

Answer 1

If this is a ford you are talking about that is normal. The programming doesnt actually mention any yellow light cause its not that important but yes, first key yellow will come on, 2nd key no yellow.

 

If this is a 2010-2015 year range f series, pretty common that the key sense is kaput in the ignition switch. Litlle bandaid to get around that is to apply constant pressure inwards on the key anytime it is in the barrel during programming.