N75 questions.. Hoping someone can teach me :)

Hi guys,

We were trying to eliminate some faults on my friends Octavia (1.8T BAM) and we narrowed it down to what we thought was a faulty N75 (turns out we were very wrong and it was a lazy actuator).. any who, I measured N75 voltage on one pin (12V) and the other side we were getting 3.5V??? I'm eager to learn so I've done research and understand the ECU switches the ground side and modulates the pulses... However, if someone would just break it down for me that would be really appreciated. I'm hoping to learn a little more and how to test things better, how the ECU controls things and makes the circuits etc.. I understand this question is very broad so just a N75 example would be great!!

Am I right in thinking an oscilloscope would of picked up that digital signal to ground (the pin I measured 3VDC on)?

I also can't grasp how pulsing a coil will rapidly modulate boost control..

Thank you,