Help with a "Start Guard" hook up.

[5 OOh!]

Hi all. I'm in the process of rigging a new year 2010 2320SL. After reading posts on this board, I purchased a Start Guard to remedy problems I had on my last boat. My question is how to hook it up. The Start Guard comes with pretty straight forward instructions, telling the buyer to run the positive wire from the ignition switch to a certain post on the Start Guad. My problem is, I cant' identify which wire coming out of the ignition switch is the positive wire. There's a round thing on top of the ignition switch that I think is an alarm. Some of the wires are multi colored. There's no simple black, red, green, etc. to identify. The wiring diagram that came with the boat isn't any help. Any assistance here is appreciated.

 

[Brent]

a digital voltmeter will display + or - neg symbol
Try it on a battery then the switch