I found this similar in eBay:
If you watch at the photos you can see manufacturer and model no:
If you google it, you find some vendors or distributors or whatever they are, but not a schematic or wiring diagram.
Anyway with 3 pins, one must be GND. Open the case and try to figure wich one is GND. You have to guess what other two are. They may be voltatge or current driven. Try injecting very small current in them to see if anything happens.