I currently only have FOBs with lock/unlock and no remote start... but I can remote start with Ford app. Would I be able to add a new FOB with the remote start function, enable via Forscan and it work?

 

I don't think simply adding the three-button fob will work. There has to be a receiver module installed for the remote start function to work on the fob, IIRC. Also, there's no need for a new fob, as a combination of lock, unlock, then lock performs the remote start with the two-button fob (again, IIRC). The FordPass app doesn't use the physical remote receiver module, but handles remote starting via software within the app and truck.

There is a thread or two here on the forum that discusses adding the remote start module, you might have to search to find them but they describe the parts and procedure required. The search function within the forum is hit-and-miss (mostly miss) with finding what you want. I've had better luck using search engines and adding "site:ford-trucks.com" to the search string (minus the quotes).