ACD Control: Howzit work?

[WAM]

I know there's a hydraulic clutch system that locks the ACD upon ECU command. But what does the ECU actually command? Computer output signals don't power hydraulic pumps. So what's between the ECU and the hydraulics? Stepper motor maybe....solenoid valve etc? Or does the hydraulic pump maybe receive variable voltage from some sort of controller device?

What I'm really wondering is if I can temporarily hack the ACD control system and put in manual dash switching to get full lock, full unlock etc. Before I get into the world of ACD reflashes, I'd like to know exactly what does what to the handling.

[WAM]

So I take it you guys don't know either.

I did find out if you pull the ebrake 1-click it shuts off the ACD clamping. That gives me at least something to test.