You should see 12V at the jump start terminal (the big silver nut on the firewall). It is directly connected to the battery.
http://www.shipkiller.com/Battery_System_Schematic.pdf
Since you have no power to the fan connector, you need to ohm out (continuity check) the wiring of the circuit.
I would ohm out the power wire, from pin two (2) on the fan plug (X1800) to the fuse block. I would then ohm out the ground from pin one (1) on the fan plug to ground. These ground wires go to a common ground buss point. I am having issues with my WDS so I will tell you were the ground point is after I get my java issues fixed.