My brother-in-law just went threw this and a used one may not be programmed the same, but this is what he did All Computer Resources, INC. All units are VIN programmed and updated, I believe it was $179.00-379.00 (depends on year) on sale as they are normally higher. He had to mail in his and they either repair it or send you another one programmed per your VIN and that is what they done for him and it worked great. The Phone number is listed on the site and he called them first and talked to the and I suggest you do the same, it was fast in a few days he was back up and running. They are located in Miami, FL. The URL I will put in a post below just copy & paste it to new browser window.
