DIY Budget Start Button

[seattlejester]

Warning this is going to be a fairly long post...scroll to bottom to see my question.

 

So I had this idea in my head for a while, nothing new really just a push start, but I never had a reason to really look into it.

 

Well the other day, I handed my keys to a friend to take my Z for a spin. He accidentally put the door lock key in the ignition and then managed to turn it pass the ignition lock. Long story short, we ended up braking the key to not make it look like the car had the keys left in it, and I have been essentially hot-wiring the car to drive it around.

 

So I ordered a new ignition, but I figured since it was broken in the meantime, why don't I try playing with a budget push start.

 

Note this is on a 1971 240z with an E12-80 meaning it no longer has the ballast resistor.

 

Step one is to remove the ignition assembly by drilling out the two safety screws so I don't have to worry about the steering column lock. The portion that starts the car is the little solenoid/switch on the back of the ignition barrel. There will be two wires that will need to be grounded (formerly grounded through the steering column via attaching to the ignition barrel.

 

The main issue people seem to run into is that you still need to turn the ignition of the car on, and then you can press the start button, this requires a smart switch or a simple board. My plan is even simpler than that, use two switches like race cars. One to turn on the ignition, and a momentary to run the starter.

 

I've done a fair amount of searching and I've come up with the following wiring schematic.

 

So my main question boils down to the starting. The stock switch has essentially two ignition wires. One to bypass the ballast resistor for when you start the car, and one employing the ballast resistor while the car is running, only one of these is active at each point, one is on in the on position, and the other is on when you are cranking.

 

This is unique to me, but since I am not running the ballast resistor, will the wiring diagram above work? Mainly to have the ignition on (via the push button on/off), and then just run the starter motor

(via the momentary)? My thought is that since the ignition is already on, it will be redundant, if not hazardous, to run two ignition signals to the coil. Or am I wrong and I need to run an additional signal with starter motor? 

[m1ghtymaxXx]

I installed a start button in my 83 out of necessity when the starter contact gave up in the ignition switch. Apparently fixing it properly isn't hard at all, but bu the time I learned that I was long done. My setup still required turning the key to the on position. Just to get it going I ran a fused wire from the battery terminal to a momentary push button. Of course this is a bit of a fire hazard and it also means the starter can be fired without a key. I then picked up a $5 dollar fog light relay kit and ran it off an accessory wire so that the starter would only fire with the key turned. Of course this also prevented the full amperage to the starter solenoid from running through the button.

 

Electrical work is certainly not my forte, but with some consultation from my millwright roomate, it was a fairly simple job.

Edited May 17, 2013 by m1ghtymaxXx

[noelawinslow]

The fuel pump system has a wire that runs 12v when the engine is running. A relay connected to that could run the Bw wire to the fuse link only when the engine runs. That could also connect the accessory wire, and the push button would activate all three at once. Is there any drawback to running accessory, ignition, and starter at once?

[noelawinslow]

Forgive the fact that it's a napkin. Anyone see any issues with this?