Originally Posted by
pizzaguy
Neither. The PTCM runs the show, period.
Pin 1 of connector C1 at the PTCM goes to ground to engage the S/C clutch. As to how the PTCM makes the decision to engage the clutch, it is my understanding that the S/C engages at a certain RPM.
I wonder if I am right here.
It seems to me that it engages at a certain throttle condition, regardless of RPM, that's why I'm asking. I know it's throttle is by wire but it seems to me that the signal to the SC comes from the small control unit in the throttle body with the little wipers on it. Sorry, I didn't take the time to look it up, not sure what it's called. I'm sure somebody has knowledge of how this functions. I'll try to take a look at the schematics and see if I can make heads or tails of it.