i just got a new fob for my Regal, i had to hold the lock button for 10 or 15 seconds, when i let it go i got the 2 dings, i have a regal so im not to sure about the gtp for sure but that may work. oh and i read some where while looking for a new one that if the replacement fob has the same fcc# on the back as your old one had it wont reprogram, what sucks is u lost the old one so u don't know the # anymore, i bought my car with out a fob so i was going on pot luck i guess.