Bridging connections on diagnostic box

[nikp]

Ok, i have been studying the wiring diagrams for the coolant system (I determined that my fans are not coming on when it gets to a particular temp - so i currently have to control the fans with the aircon button!). The circuit that it turned on via the ECU, also has a feed to the diagnostics box - and this seems to be a switched ground. So, can anyone confirm that if i bridge the pin for the diagnostic circuit on the cooling fans relay to ground (with the ignition on), will i get a voltage between the fan motor supply?

I will i end up blowing a fuse? I am pretty sure that i will get my desired voltage (So i can figure out which wires they are - the colours don\'t seem to tie up with the diagram!) between the live and ground. Can someone confirm?