gps locator 2000 saturn ls2

So i installed a gps tracking device for my dealership that sells buy-here-pay-here vehicles, and all i needed was the starter wire ( yellow ) 12v ( red ) and ignition ( pink ) . I looked up the location of these wires and the12volt.com site had them listed as ignition harness. I went and checked voltage at the red wire and got nothing, i also checked the yellow wire ( starter ) and had a 12 volt drop when turning the key to run, so i figured i had the correct wire for the starter. When i snipped it and tried to start to see if the starter would engage, well , it did? did i get the correct wire? or is there another yellow wire at the ignition harness? any help is greatly appeciated!

Sorry but that's why we tell people to test! The constant should read 12v+ all the time, the ignition should read 12v+ on turning the key and whilst cranking,the starter wire should only read 12v+ during cranking.

yeah i figured that. problem is these people are always in a rush. this site is awsome in that it gives you the color wires and locations, but i did run into multiple color wires from the wiring harness location. i was able to locate a 12v constant, and there was only one yellow wire at that harness, so i was confused as to why it would still start after snipping it... oh and as a rule of thumb, most constant 12v and starter wires are of a thick gauge , correct?