Look here: how to create communication between ECU and DAS/Xentry/Vediamo without vehicle
Communication with Vediamo:
I try Vediamo with some ECU's without car and the function was without any problem, 120 Ω resistor and +12V and GND for the ECU and 100% OK
the ECU must have the same power line as in the car, not enough everytime only +12V and GND, some ECU need power signal from igniton switch like 15-line ! or have multiple +12V power as for example engine ECU !
i try it before with one resistor 100 Ω, because i haven't exactly 120 Ω value and this was 50/50, the function was bad...the resistor must be exactly 120 Ω, without any tolerance !!! Be careful
Communication with DAS/Xentry :
DAS/Xentry is not factored for the same playing as Vediamo...then you can't await the same function...
That is, ECU without car is not possible, because DAS/Xentry read first information about the car from ZGW, CGW....VIN and other info