OK
For basic comms checks, it is pins 1, 4, 6 and 10 which are relevant and the GS911 is suggesting no power on pin 10
Check for voltage between pin 4 and pin 6 with ignition off to confirm that is in place ------------12.2V with ign On ---11.9V
Check for voltage between pin 4 and pin 10 with ignition on to confirm that is in place-----------0V
Plus check continuity of pin 1 back to the Motronic---------------0 ohm and 0V
Confirmed 4 Brown is earthed.