2001 mercury 25. Help me understand the yellow /black wire

[gunz]

I know its the kill wire. But I am guessing ti needs a ground to shut the motor off? I got my cables and universal control in today and will get them installed tomorrow. Can pull start the motor (2001 mercury 25 2 stroke) but how do I shut it off. I don't have a wiring harness yet. just the factory plug on the motor. Need to make a run to see how well I like this motor on my boat and if my weight distribution is anywhere near correct. Thanks in advance. Keep those line tight.

 

[gunz]

I figured it out. I grounded it to kill the motor. Got it all wired up and running now.