Hier het Engelse antwoord dat ik kreeg, inclusief de link:
You would have to disable text features for your navigation to stay displayed on the screen.
To disable the text feature, you would need a FAT formatted MicroSD card to load a couple configuration options onto your GROM unit.
http://www.gromaudio.com/support/ipd3-config.html
Please scroll halfway down the page and locate Select Car Make.
Click the drop down menu and select BMW 97-06 and you will see options m and x appear in the chart below.
Check the box to the left of option m and x and you should see m= 0 and x= 3B appear in the Result CONFIG file box below.
Change x= 3B to x= 0 press enter to have an empty line underneath and click Download config file.
It would look like:
m= 0
x= 0
After downloading the config file, please make sure the filename is: gromipd3.cfg and load it onto a MicroSD card.
Please turn off the vehicle and disconnect the GROM unit from the 20-pin GROM harness.
Please take off the cover on the GROM-BT3 unit and expose the circuit board.
Please insert the MicroSD card in the MicroSD card slot on the circuit board.
Once MicroSD card has been inserted, reconnect the Grom unit and turn on the vehicle.
Test out your navigation screen in GROM mode with music playing.
Please keep in mind that if the GROM unit loses power, the configuration file will be deleted from the GROM unit.
That means that every time the GROM unit loses power, you would have to load the config file again.
Please do not disconnect unit after loading config file.
Thank you.