OK, i'm totally stupid when it comes to anything regarding electronics, so please excuse me if I sound like a fool. Also, wasn't sure what forum to post this in so I'm probably just racking up idiot points right now .

So, I have an Apexi turbo timer and have yet to rig up the parking brake safety feature. I intend to track this car from time to time and I do not want it to sit there with the parking brake on while the timer counts down after a hard session. So, my idea was to put in a switch so that I can turn the parking brake safety on/off. I have a grey wire that comes from the TT and splices into the parking brake wire. The rocker switch I have has two prongs on the back. Do I just simply cut that grey wire and solder the ends on to the switch? Or, does it need to be grounded when off? Sorry for the stupid question.