The simplest way to do the starter kill is to use a 30 amp Bosch relay. Wire it so the relay has to be energized to complete the starter circuit at the ignition switch. Here is one way to do it:
At the ignition switch, there is a black 6 pin connector, and the starter wire should be green. The starter wire has voltage on it only when the ignition key is in the start position. Cut the starter wire so you can make the connections to the relay. On the steering column there is a white 4 pin connector for the brake light switch, and there should be a wire in the connector for the 12 volt output to the brake lights when the brake pedal is depressed. The wire should be gray. Tap into the gray wire with a separate wire so you can connect it to the relay. Be sure you check the functions of the brake light wire and the starter wire with a voltmeter to be sure you have the correct wires.
Wire the relay like this:
Terminal 85 to chassis ground
Terminal 86 to the positive brake light output wire
Terminal 87 to the ignition switch side of the cut starter wire
Terminal 30 to the starter side of the cut ignition switch wire
No connection on terminal 87a
In this configuration, you would have to press the brake pedal to energize the relay and complete the starter wire circuit in order to start the car. The car may wired like that anyway, or it may be wired so you have to press the brake to shift from park to drive.
If you wanted to make it more complicated for a potential car thief, put a simple toggle switch in series on the ground wire for the relay and hide the switch in the glove box or the center console box. Then you would have to flip the toggle switch before the relay could be energized and allow the car to start. This would create a second step before the car can be started and possibly a potential car thief would give up on your car and move on to another car. If the car has a cigarette lighter, you could also get very creative and unplug the lighter if you don't use it for anything. Then connect the ground and positive terminals on the lighter socket in series on the ground wire for the relay, so you have to push the lighter in and make it act like a toggle switch to complete the ground circuit for the relay.
You can wrap the relay with electrical tape to disguise it and also insulate the terminals, and then hide the relay pretty much anywhere you wish.
You could also buy a simple keyless entry system, and it will have its own dedicated starter kill output that is connected to an outboard starter kill relay. Directed Electronics (DEI) makes several keyless entry systems that can work the same as the factory Hyundai keyless. They also make a factory keyless entry upgrade system that includes and alarm and starter kill outputs, which would allow you to add starter kill, parking light flash and an alarm, but continue using the factory Hyundai keyless entry remotes. You can visit
www.directed.com for more info and to find a DEI dealer in your area.