that is for the alarm...if you have the alarm that disables the ignition then you need that switch if your remote breaks/gets lost. If you get in and your aarm is going off you can turn your key to the on position, and then flip that switch back and forth once, and then the car will start and your alarm will stop sounding. Found that out the hard way...lol
Doesn't that kinda defeat the purpose of an alarm and starter kill? If the average alarm comes with this, theives are gonna know about it and be able to start the car just as easily as you could.