pins layout on umbilical cord

I want to order custom umbilical from PS to a control unit of the preamp.
Manufacturer of the custom umbilicals needs to know a layout of the OEM umbilical, that is being replaced.
Since I am eclectically- challenged individual, I would like to ask for the guidance.
I do have Fluke multimiter, and to my understanding it should be in Ohm setting to check continuity b/w female and main connectors (they are XLR type connectors) on the PS and control unit to make sure Pin 1 of male corresponds to #1 hole in the female.
So should i do it b/w two chassis or on the actual OEM umbilical cable?
Please help!!!