Keith
How are you receiving GPS signal on ft400 when it is in the rack?
Hi Mark,
There are 3 ways to solve the problem, first is to use an external GPS like this Garmin GPS-18. This is the solution I use in the Tahoe. I soldered my own mini stereo plug in place (page 84 in the owner's manual) and tied the power to my 5 volt converter in the console, then set the FTM-400 to EXTERNAL GPS.

Another choice that did not work for me was the GPS repeater. This thing played HAVOC with the multiple other GPS units in the Tahoe so it was quickly scrapped, on the other hand if you are inside a building it should work well.

I got the GPS repeater and bluetooth ideas from this guy: https://www.youtube.com/watch?v=Q7oQYwurG8w
My solution to this particular problem is to just enter my location manually and turn the GPS off.