Push-button Ignition how-to
 

How to install a push-button ignition for use at stop lights. The idea is this: you start car normally with the key, drive until you reach a long light, press the kill button[work in progress] to stop motor, when ready to go, press the start button.

This is how I wired mine. Unless you have an 80's or 90's Chrysler or derivative, you will need to do it differently. Pressing the button with out the key in the 'run' position will crank the starter, but the fuel pump will no turn on, also you can't shift out of park or unlock the wheel.

BOM:
1x N/O momentary SPST push button switch
2x SPDT 10A, 12v coil, relays
1x Plastic box
3x 3M 905 snap-down wire taps
Wire of appropriate gauge
Other stuff like zip ties, tools, magnetic tape

#1
Acquire very affectionate stray cat to lend a helping paw.
I don't know who owns him, but he always joins me when I work on my car at night.
http://farm4.static.flickr.com/3058/...5dbb1db2_b.jpg

#2
Take apart steering column and lower dash.
The blue twine will be used to fish the wires through the protective shroud.
http://farm4.static.flickr.com/3097/...c58e527b_b.jpg

#3
This is the ignition switch harness.
Pin numbering goes from right to left, with yellow being pin one, and red being pin 7. On my car , when the key is in the 'run' position, pins 1&7 3&7 must be connected to start the engine. Pin 7 also provides the power to drive the relays.
http://farm4.static.flickr.com/3060/...ef41590b_b.jpg

#4
Tap switch wires.
Make sure that the taps don't interfere with the tilt mechanism. Ignore the cruise control harness on the left.
http://farm4.static.flickr.com/3281/...78b44da3_b.jpg

#5
Wire relays and run wires into/out of box.
Black wires on the right go to the taps, wires on the left go to the button and a ground lead for the relay coils.
http://farm4.static.flickr.com/3017/...a08b6f7e_b.jpg

The relays in this schematic are drawn strangely, I had to correct something after I scanned the drawing.
http://farm4.static.flickr.com/3189/...0acf2d5d_b.jpg

#6
Install push button.
I'm putting in right next to the shifter, so i don't have to move my hand from the knob .
http://farm4.static.flickr.com/3190/...961a5a4b_b.jpg

The second hole is for a future kill switch.
http://farm4.static.flickr.com/3281/...f7fac95b_b.jpg

#7
Install box. Tuck wires away.
The box is being held in place by magnetic tape. The wires have been routed under the dash and held in place by zip ties, leaving some slack for when the wheel is tilted.
http://farm4.static.flickr.com/3066/...656f8240_b.jpg

That's all 'till mornin'

Thanks, great how-to. Looking forward to the kill switch too.

Very nice. I was looking for a way to do this. Now I have a much better idea, thank you!

Looks nice wikityler. I remember this from another thread and I like the professional look you're going for. One suggestion, when you install the starter switch, find the kind with a safety cover you have to flip up first so it doesn't accidentally get tripped while the engine is running. Since you've mounted it on a horizontal surface, if something falls on it, a cat for example, that could be really hard on your starter if the engine is running. Keep up the good work.

Or perhaps he could have a second relay prevent the switch from activating the starter while the engine is running, that way wikityler wouldn't have to move the switch and there would be a failsafe. By the way I forgot to mention that I liked your little helper in the first pic :thumbup:, "Now fish out the blue twine kitty, with your claws...that's it...."

Schematics will be necessary. Check your local library and see if they have the Mitchell1 repair book for your vehicle. The schematics are very thorough and understandable.

I will not toot my own horn, however, I will allow myself a moment of brevity. I used to be an Electronic Engineering and Technology major at school, as a result, I have an untapped and unused knowledge base that is just going to waste. I think in schematics, now, when I look at electronic components I see circuits :thumbup:. No offense intended. By the way, the taps look pretty slick.

With this, will the radio still cut off when you push the button? (It does it in mine when I use the key, but if I install a button I hope that it doesnt cut off anymore)... ??

And why two relays instead of just one?

So for you they aren't needed, but it's still easier to read functional description than probe around with a multimeter. For example the book said:
Acc 6&7
Run 2&7, 4&5
Start 2&7, 1&7, 3&7

If it cuts out with the key it will with the button. As far as the car is concerned, it can't differentiate between the button and the key. I think most cars will cut off most accessories (lights, radio, climate control) so almost all power can be dedicated to the starter. Do you have some kind of high-power fancy car audio system?

I used two SPDT relays because they were cheaper than one DPDT relay with the appropriate current rating.