Lamda control relay power check

[Talonz82]

I would like to check my ecu(lamda control unit) to see if it is getting power, I'm struggling with a rough idle issue on a 1980 911 sc with the 3.0.

I believe the relay located on the left side of the unit gets power from the dome lite fuse, but where and how do I check to see if it is getting power, and yes you guessed it my dome lite is out right now do to another problem. The glove box lite which is part of the circuit is working.

I'm wondering about this matter because my Bosch fuel injection books tell me to unplug the unit and I should notice a change in idle, which I do not.

Any ideas from you guys is very appreciated.