Engine Control Unit (ECU) Kilometer Reading

Hi,
I drive an A4 TDI model year 2002 with 130 horsepower.
I've been having a problem with my GPU since yesterday. It won't activate anymore.
It was self-installed and has been working for 3 years.
I checked all the switches with VAG Com, and they are all working correctly. Now I've noticed that the speed is no longer displayed in measurement block 6 of the MSG (Modular Steuergerät). The speedometer is working in the navigation system and the instrument cluster (KI). If the MSG doesn't know how fast I'm driving, it can't use the GRA (Gasolinestation-Anzeige - likely a typo, meant to be 'Gas Return Assist' or similar). Does anyone know where the MSG gets the speed signal from?

Thank you and best regards.
Maik.