The Complete Idiot's Guide to Building a Switch-based Ignition (Also, how to hotwire a car):
1) Get your wiring diagram. (If you can't find one, use the forum's email function and let me know. I've got one for damn near every car sold in America for the past 50 years)
2) Locate the following tires going to the ignition switch:
- Accessory (Will connect to one or more relays or fuses)
- Ignition (Will connect to a relay or fuse)
- Starter (Will connect to a relay or fuse)
3) Make note of any "other" wires that go to the ignition switch assembly and make note of what they go to. One of them will either be a 12v always hot (goes to the battery positive, possibly via a fuse) or a ground (goes to either chassis, another ground, or to battery negative). This 12v hot or ground will be called, for our purposes, the "power wire". If you have both a ground and a 12v hot, then you need to read and comprehend the part of the diagram that has to do with how the original ignition switch worked.
4) Connect a regular ol toggle switch between the Accessory line and the power wire. Flip the switch and notice your radio and shit comes on, just like you put the key in the accessory slot.
5) Connect another regular ol toggle switch between the ignition line and the power wire. Flip the switch and notice the car responds just like you put the key in the ignition slot.
6) Connect a momentary pushbutton between the power wire and the starter line. Push it and note the engine cranks.
How to use it:
1) Turn on the accessory power and ignition power.
2) Push the starter button.
My starter doesn't crank!
1) Are you sure it worked in the first place?
2) Examine your wiring diagram for any interlock circuits. Using a multimeter, check to make sure those interlock circuits are doing what's expected of them, and if they aren't, fix them.... Or if you don't know how to make sure they're working, just bypass them. If you don't know how to do that, I suppose I can help you.
My starter works, but the engine won't start!
1) Did you turn on the ignition switch?
2) Did your engine EVER start?
3) Check the diagram for interlocks on the ignition circuit. This could be things like a security system, or a goddamn electronic coded key. Bypass them.
Fancy modifications:
A) Technically, you don't need two switches for accessory and ignition - you can just tie the two lines together on the same half of the switch.
B) Technically, you don't need that switch at all, because you need a killswitch that interrupts the ignition circuit anyway. Use a 4 pole killswitch with the battery disconnect across one pair of poles and the ignition/accessory switch setup on the other pair. Note that you will need to shut off your killswitch to power down the ignition system, which may or may not be a good idea, depending on a variety of factors.
Wiring in your killswitch:
If you didn't do B from the mods section, then just take your power wire from the ignition switch and run it through the second set of poles on the kill switch. It'll perform the same function, but BOTH switches will have to be in the on position to function, and either one can be shut off to remove power from the ignition system (the battery will continue to supply power to other systems if you don't shut off the killswitch, though).
Bonus feature - Hotwiring a car:
Find the ignition, accessory, starter and power wires. Cut them, strip them. Twist accessory, ignition and power wires together. Touch the starter wire to the unshielded bundle to operate the starter. If this doesn't work, the car is either broken, has a security system, or has an electronic key.
Extra safety (at the end for darwinism): Pull apart the stock ignition switch assembly and physically remove the goddamn steering wheel lock. God only knows if that thing's going to try to kill you in the middle of turn 1 or not.
Driver, Pit Monkey, Rod Buster and Engine Fire Starter
Team FinalGear
