Tracks 127 to 140 cover the connection of the radio (R), cigar lighter and it’s light (U1) and the glove compartment light (W6) into the vehicle networks.
For now, I’ve allocated a module J-Media to provide the network connection to those devices The module is most likely to be physically integrated into J-HVAC due to proximity, J-HVAC has a chunky, 6 mm² power supply cable and it has a common chassis ground point with most of the things behind the dashboard’s skin.
If integrated, the green power supply cable as shown above will disappear.
The node, in addition to the LINbus connection, taps into the vehicle speed signal to relay to the radio which could adjust the volume according to vehicle speed using what VW call “GALA” (which stands for Geschwindigkeits-Abhängige Lautstärke Anpassung); and aren’t you glad that they call it “GALA”.
There are other tricks that J-HVAC could play using the same speed signal, including throttling of the fresh air intake at higher speed, using an add-on servomotor and flap. But more on that later.
J-Media not only provides power to the radio, it also proxies the dashboard illumination brightness setting obtained by J-DC.
Comfort features such as footwell illumination are most easily added to J-Media as it’s mostly dealing with devices underneath the dashboard.