Step 3: Place both gmapprom.img and gmap3d.img into the gmap folder of the latest opnion zip file. If you don't have the latest opnion file, you will have to re-download this gmapfile from this website
Step 3: Run gimgunlock.exe to automatically unlock the two files and copy them and the car.inf file into the heavily encrypted Garmin folder off your C: drive. It will take a few minutes to complete, and you will see a "welcome to gmap3d.exe" message saying that the two files and the car.inf file were unlocked. Use this file to place them on your computer—do not put them anywhere on your computer yet. It is possible to get the TMC or INFRU RCX 800 back to work no matter what you do once you lose the file.
Reversal suggestions: Some of the many possible Garmins available after the manufacture of the 800 can be reset to factory settings. This can be done by using the gmapprom.img unlock file. One manufacturer makes gmapprom unlocker files that can be used to unlock all available garmins. See the link which says to use this to unlock all gmapps. d2c66b5586