Be very careful doing it if you do! My car did just this the other week when I pulled into the drive and it tried to connect with my home wifi to update itself. It too kept cutting in & out. The next day my voice control kept saying 'system not ready' and the maps started playing up. So I went onto the Ford website, followed the instructions & downloaded an update. It took about a 30 mile drive for it to finish downloading!
Now my voice control is very erratic, the sat nav keeps thinking I am driving in the Humber, the screen flashes and can't seem to decide whether it is night or day illumination wise, and my CD player cuts in & out at random.
I went to my local Ford for help & they wanted £100+ pounds to plug the car in & scan it even when I kept telling them it was the SYNC3 system playing up even before they would charge me nearly the same again for an 'upload' to fix it. As it happens whilst I was waiting to talk to the service lady another man was talking to her saying his car had a SYNC3 problem, had been to them to 'fix', and the system was now even worse than before. They were discussing even more money to 'try' other fixes to it!
I am therefore currently in discussion with Ford Customer Care about the problem & have asked them for a complete software update free of charge as I don't see why I should pay my local dealer several hundred pounds of an update that I can get off their website & do myself for free? Unless the one on the website is designed to crash your system & make you go & pay a dealer to fix it?
Thanks for this post. I've been struggling with the latest Sync update for my mkIV and Ford finally told me take it to a dealer. I'm not going to pay for what should be a free upgrade, thanks Ford. I suspect your issues are caused by the same problems I'm having but i didn't update my car after noticing file errors when extracting the ZIP archive. I've tried to download the update on 3 different machines, using 3 different browsers on each and extracting using Windows (8), 7zip and PKZIP. Windows and PKZIP both error on the same files and won't continue the extract, 7zip (advised by Ford customer service) will extract but reports file errors on the same two files.
As there continues to be n issue with this I won't bother updating. I suspect the mk3.5 and the mark IV units are electronically identical. If this is a common error maybe we can gain some traction (Twitter??) and lobby Ford to do something about it.
Any Ford service employees on here, I'd be interested in your thoughts/ experience??