The reason you cannot use a used chip key is they talk encrypted. From the factory, they all speak the same default encryption, and when used, have been programmed to only talk with a certain encryption.. You have to take them back to the factory default to reprogram, but that takes either talking in the unknown encryption, or brute force attempts. Brute force cracking will lower life of key or kill it, and takes too long to be cost-efficient... (days of trying )
I think this guy below has come up with a way to throw a couple attempts at it, then crack the response it gives back... then he narrows down the possibilities to a manageable number... and sets them to default. He has to be banking some serious cash on this business plan, I am jealous!
I had him de-program a couple keys, and I am very happy!
Matt Burkhart @ carkeysfast
I think he sells refurb with blank shell for $70, search for:
05-07 JEEP REMOTE KEYLESS ENTRY KEY FOB UNCUT BLANK I5
Here is the blurb on his website:
"I BOUGHT A CHRYSLER KEY ON EBAY THAT CAN NOT BE PROGRAMMED, CAN YOU HELP?
Absolutely, even though these keys have been around for almost a decade, there are still sellers who are unaware that they cannot be reprogrammed. Just Call or send a note from the Contact page, for a small fee, we will gladly make your key usable again."