Here's a fun project that I did to my very first car. When I first got it I was quite happy with my purchase, but soon after that I found that I really wanted a sweet push button ignition and an engine kill switch, like a rocket or a race car or something cooler than an early nineties economy car. Well, it has been nearly a year and today i tore apart my dash, cut up some wires, soldered and drilled and figured and puzzled for about 5 hours and now, the final result, you will see in this instructable.
I'll show you how to wire in a push button ignition and an engine kill switch in your car. It's easy, as I have done all of the puzzling and figuring for you. It should take between one and two hours, depending on how fast you can take apart your dashboard, but could take considerably longer. This project cost me like 25 bucks for a soldering iron, wire, one relay, two momentary buttons, and a switch. If you have some of these it will be cheaper. Either way, this is a small price to pay for such a cool feature.

Step 1: Gather Materials

For this project you will need:

One Single Pole Double Throw Relay (a SPST normally open will work as well)
One Momentary switch, Normally open (toggle or button)
One Single Pole Single Throw Switch (toggle or button)

Soldering Equipment/Knowledge
Wire (I used 18 g)
Screwdriver
Wire Cutter
Other various tools

Be sure that whatever momentary switch or button you get is a normally open, momentary switch.
anything else will not work for what we need.

Step 2: Open Up the Dash

Here you will need to get inside your dashboard to where your ignition harness is. This is near the keyhole. Once you get to this bundle of wires you will need to cut the Ignition Wire and the Starter wire, so also disconnect the battery first. You will have to find a wiring diagram for your car to know what wires do what. I can tell you that for Hondas the Ignition wire is black and yellow, and the Starter wire is black and white.
Cut these wires and strip the end enough that you can solder it or splice it well.

Just a caution, this step, more than any others so far, has a potential for really messing up your car. as long as you cut the wires such that you can splice or solder them back together you should be ok, but be aware that cutting wires to your ignition could become a problem.

Step 3: Assemble the Hardware

Now we will solder together the chain of switches and wires and buttons and relays to make this all work. This is by far the easiest step.
Basically the way this all works is that the Ignition wire, which needs to remain a closed circuit as long as the engine is going is connected to the relay, and we will borrow some of the current going through it to switch the relay and start the engine. Solder the wire ends to the Ignition wire or the starter wire as indicated.

Step 4: Put It All Under the Dash.

Now that your parts and wires are all wired in its time to test it. Turn the key to the "Engine On" position. Flip the switch on. Push the button. If you have wired everything all correctly you will start the engine. Now put your dash back together and put your buttons and switches wherever you like. You can drill holes in the dash and put the button and switch through there, or you can hide it under the dash.

Step 5: Show It Off to Your Friends

Alright! now you have a push button ignition in your car, just like all the high end sports cars, rocket ships, and computers. Go ahead and show it off, thats what you did it for, right? Be sure to post a picture here so we all can see it.