Ignition & Starter Interupt Difference

I'm new to this forum so please excuse any dumn questions.

Ok, what's the difference between a Starter Interupt and an Ignition Interupt?

Thanks for your help

2000impala

Well, you know when you turn the key to Run, and the seat belt buzzer and the heater come on?  That's because of the ignition wire.

And if you turn it all the way forward to Start, the starter motor cranks the engine, of course causing it to start.....that's because of the starter wire.

Well, if you use a relay to interrupt either one of those wires, the car isn't going to work, which means it can't be stolen (at least until the thief disables or bypasses your setup).

The biggest concern is that if you interrupt the ignition wire, and you make a poor connection or your wiring falls off or the alarm turns on by accident somehow or whatever..........and this might happen while the car is in motion..... the car's engine is going to stall while you're on the highway or something, creating a dangerous situation.

On the other hand, the starter wire is only used during starting; once the car is running, the starter wire is no longer needed.  If you do a starter kill and it goes bad for some reason, the worst thing that will happen is the car won't start.

Most basic alarm installations interrupt just the starter, mainly for the reasons stated above.  Of course, if you're doing an advanced, high-security installation, you might consider doing several different interrupts-----for example, starter, ignition, and fuel pump-----in the hopes that it will take the thief a long time to find and defeat all of them.

It should also be noted that standard-shift cars can easily be push-started, rendering a starter kill ineffective---it is wise to try to interrupt some other wire as well.