After testing the wires we've figured out which ones are which. They are as follows: The first grey wire is the ground, the second grey (with white stripe) is the test wire, and the brown wire is the 5v source.
So to test a 94-95 car you would put the negative lead on your voltmeter to a good engine ground or the first grey wire. Then you would put the positive voltmeter lead to the middle grey with white stripe wire.