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!!!
Why not just email them photos?
Manufacturer wants to know how numbered male pins correspond to female receptacle, 1 to 1, 2 to 2,etc.
I don't think pictures would help him
"So should i do it b/w two chassis or on the actual OEM umbilical cable?

Since you are having a "cable" made, you need to take the readings from the OEM cable itself. As long as it is the correct cable anyway.

You could also contact the preamp manufacturer and ask how it is wired.
Take you Fluke and set it to read ohms. Put one of the test leads on a pin in your umbilical. Take the other test lead and touch it to one of the pins on the other end of the umbilical. You will either get a reading of 0 or 1. 0 is what you are looking for. That's the other end of the wire that you put the first test lead on. Make note of the pin location on both sides of the cable. Then move the first test lead to a different pin and repeat the process. Once you have all the pin locations accounted for, thatÂ’s the wiring diagram you'll need to make the cable.

A word of caution. If the person who's making the cable for you doesn't know to do this, you need to find someone else to make it. Or just do it yourself.
Thank you guys
Think I got it