sgimips

I'm trying to track down a the correct pin out for the rear HVAC control unit to figure out which one is power, ground, and data. The part number is A2228300085.

It has a 4 pin connector of which I think only 3 are used:

Pin 1 Purple?
Pin 2 Brown?
Pin 3 Red?
Pin 4 N/C?

Any help would be greatly appreciated!