I recently lost my master key and valet key to my 2001 Lexus GS300 I ordered a new keyless entry key with 4C chip in it I had a locksmith cut it and he was able to get it to start the car but we cannot figure out how to program the buttons to unlock and lock the car I am successful at getting my car into programming mode but the key is not being successfully programmed I'm not even getting the fail signal

 

Wow surprised he was able to get the car to start. If I remember if you have weak or failing door locks it was harder to program. Instead cycling the door locks with the power door lock feature during the program mode I had to just flip the manual door lock