As I recall, your PASSID is your KTN for PreCheck. You just need to add it to your airline profile and current reservations. Be aware there can be a problem on your existing reservations. When we checked in the day before our first flight after getting GE, we didn’t have PreCheck on our boarding passes. I called the airline to fix it, but it didn’t work. Next was a twitter message to TSA where they checked our account and verified we were good. I think they checked a box on our profiles as the airline counter agent unchecked and checked us in again giving us PreCheck on our passes.