Pushbutton ignition wiring

[Mbufford]

Hello FFR gurus.

I’m going to be using two push buttons for my ignition system, one for ACC and one for Start. Please, spare me the comments about how using a key is easier—I don’t care and I don’t want a key.

I’m trying to emulate the same basic switching functions of the standard ignition switch, but haven’t been able to locate any diagrams/schematics for the internal switching. So, I’ve been trying to reverse engineer it from taking readings from the kit-supplied switch. I think I’ve got this circuit set designed to act just like the stock switch, but wanted to get some other eyes on the circuit before I take the time to install it. First question: does this schematic accomplish the same/similar enough functions as the internals of the stock switch?

IMG_0970.jpeg

I will be installing a coyote down the road, and as I understand it, the SMR (connected to EFI blue) and the Ignition relay trigger (connected to EFI orange) don’t need much current, as they’re just signal wires. With tha coyote setup, does the ignition switching actually need to be set up to cancel ACC during the start, like the stock switch does? My guess would be no, and that I can significantly simplify this circuit if I don’t need that switching.

Thank you!

[Mike.Bray]

Without giving it too much thought wouldn't you use a latching pushbutton to a relay(s) for your acc & ignition circuits? Them a momentary pushbutton for the starter solenoid.

I really like these pushbuttons, they are very nice! https://billetautomotivebuttons.com/...billet-buttons

[Mbufford]

Without giving it too much thought wouldn't you use a latching pushbutton to a relay(s) for your acc & ignition circuits? Them a momentary pushbutton for the starter solenoid.

I really like these pushbuttons, they are very nice! https://billetautomotivebuttons.com/...billet-buttons

I got mine from Custom Billet Buttons. So far, I’ve been impressed with the quality. But yeah, I have a latching for ACC and a momentary for start. But, I’m not going to run the primary voltage through the switches—using them to control 40A relays is much safer.

[Mike.Bray]

I got mine from Custom Billet Buttons. So far, I’ve been impressed with the quality. But yeah, I have a latching for ACC and a momentary for start. But, I’m not going to run the primary voltage through the switches—using them to control 40A relays is much safer.

100%, the pushbuttons only control the coils of the relays.

[BrewCityCobra]

I may be reading your schematic wrong but there appears to be one capability missing. You don't have an "accessories only" capability.

The provided key has three outputs - IGN, ACC, and Starter. If you turn the key counterclockwise one notch from off only ACC will be powered constant with no power to IGN or Starter, if you turn the key one notch clockwise from off both the ACC and IGN are powered constant. Obviously two notches clockwise gives you ACC and IGN (constant) with Starter (Momentary).

Not having an "accessories only" capability isn't the end of the world in these cars since we don't have many accessories (some don't have any at all), but if you are trying to replicate the key switch wholly or plan on having a radio, then I'd replace your top switch with a three position switch with Position 1 - OFF, Position 2 - ACC, and Position 3 - IGN and ACC. Of course you have a second switch (hopefully a momentarily pushbutton) for the starting process.

[Mbufford]

Yeah, I abandoned the ACC only early on in the thought exercise because I have zero accessories that would need to run independent of a started car.