Is it possible to use a reed switch for a starter kill switch along with a couple relays. To start the vehicle you would need to pass a magnet across the hidden reed switch once you turn the ignition off you would need to use the magnet again to start the vehicle.Since reed switches can handle very little voltage I would guess it would nee to go to ground to complete the circuit. Has anyone ever done this before, I did see a slightly different version in the relays section but you would need to leave the magnet on the reed switch.
Re-read your post. I am confused. You reference the reed switch to start the car and again after you turn the key off. If you are just wanting to have to use the magnet to start the car, this will be a piece of cake. A reed switch can handle 12 volts, they can not handle large amounts of current.
If you are just wanting to have to put the magnet by the switch to start the car, the following should help. This is assuming your vehicle does have a positive start wire. I drew the picture using a standard Bosch relay. They draw around 160 Milliamps of current. Depending on the current capacity of the switch you use, radioshack does sell a relay that draws 30MA. https://www.radioshack.com/product/index.jsp?productid=2062482 Keep some extra magnets somewhere in your car. It would be a hassle to remove a speaker to get your car started.

I labeled the terminals of the relay incase you use the radio shack relay. I have no idea the layout of that relay.
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Let's Go Brandon Brown. Congratulations on your first Xfinity Series Win. LGBFJB
You might consider wiring it with a latching relay configuration. That way you don't have to hold the magnet in position as you start, only briefly pass the magnet over the relay after turning on the ignition.
Then it'll latch the relay on, completing the starter circuit and allow the car to start normally.
when the ignition is turned back off, the relay opens up again, disabling the starter.
If anyone's watching while you start the car, you could wave your hand abracadabra style, over a whole bunch of places to make it hard for them to figure out where you put your relay. If you had to hold the magnet in position while you start, it might be pretty obvious where to hid it.
Sorry I should of been a little bit clearer. dualsport that is exactly what I am looking for, any idea on what type of relay to use and a diagram or point me in the right direction to figure it out. Thank you!
Latching relay
The relay on the right is wired for latching; use your reed relay to feed the input (you don't need the relay on the left if you wire your reed relay to the (+) switched ignition source). Instead of the fused +12V source indicated, use the switched ignition source that's only on when you switch the car on. Make sure it doesn't drop out as you start, because it needs to be on during the start - don't use an accessory line, even though it might seem convenient.
The relay output can then go to the (+) coil of your starter disable relay (not shown). The (-)coil goes to ground, and you can then use the normally open (terminal 87) and common (terminal 30) for the starter interrupt.