It's been a long time since I've touched a greenstar can system, but I found this pinout.  Go to page 7.  https://www.powell.com/App_Themes/default/docs/catalog/powellagshort.pdf

The black 4 pin duetsch plug has got to be the can.  You should be able to connect it to the outlet and pinout the other wires to see what goes where.  

The old cable must have been plugged into a power plug, you may need to find a new spot to connect this or splice the power plug back on.