I'd be very interested in a guide for this.
But my main question would be, what was your original set-up?
Did you have Sync 1 like on EU cars? Or did you have Sync 1.1 or 2 pre-installed on your Fiesta like on much US cars?
I have the stock Sync 1 system on my EU car and currently looking around to changing it to the US Sync 3 version.
So definitely interested here.
Sorry I haven't been on the forum for a couple of months, just getting to answering the questions. So, as I said in the response above, Sync 1 (blue/red lcd) requires modding as the wire harness is not directly compatible, they are different jacks. If you got your hands on a male jack from a Fiesta with SYNC2/3 system and rewired it to your car (which would be totally doable if you had a wiring diagram) then you would have a chance of making sync 2 or sync 3 work with your car. Bear in mind, however, that you won't have all of the functionality, as Fiestas with Sync2/3 mostly come with electronic air control, sirius xm, backup cams, HD radio, etc. So you obviously would be missing some wires on the back of your harness, but if you got the parts such as electronic air control, HD radio, a stock or an aftermarket backup cam, you could totally enable those functions. The functions are enabled in CAN bus through an OBD2 connection. I used FORScan, which is software that allows you to browse different modules of your car and edit values in those modules. SYNC3 is an APIM module, and there is a set of values that FORScan can read from that module. Those values are editable, and represent toggles for certain functions of the car. For example, I enabled my SYNC3 (for ****s and giggles) to have dual zone climate control functionality, which looks cool, but doesn't work, because my car lacks the dual zone AC. I still have the spreadsheet I made with trial and error of what those different values represent. If anyone is interested, I can tell more.
