Joe, the dealer just dropped my car off after installing a new 'GPMS' module. I won't know until I drive home from work if everything is ok, because the thing usually starts of 'ok' but gets farther off as I drive.
I did see in the service ticket that if the problem continues to move the GPMS to another area, as it could be RFI (Radio Frequncy Interference). I don't know where the GPMS is located.
Dealer had C-Max in for the TSB. Unfortunately, my C-Max already had the most current IDS. Took technician for a drive and showed him how the GPS displayed car as off road from the current vehicle position. He said other Ford models have had similar problems which originated with the antenna. He will need more time to trouble shoot and will also contact Ford to see if there is a solution. I will need to make an another appointment and leave C-Max for technician to figure out why it's not working. Will keep everyone advised when I have more news to report.