The car was due for a service and the day before I was to take it in for the service the car would not start.
A message came up on the screen between the speedo and tacko “No fob detected”
I called the Jeep Assist and a very switched on guy turned up in a sort time and showed me how to start it even though this was a hit and miss method, so when he started it he told me to drive it to the dealer straight away. Apparently on the Grand Cherokee the button can be removed and the key used but this is not on the Cherokee.
Apparently no part was required but just a software update.
So got the navigation update 16.16.13 but did not cure the loss of signal when exiting main roads or motorways.