A Minimal Ignition Switch

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Nov 15, 2023 | 02:52 PM

#16

6 by 8

Laughing Gas

Joined: Dec 2020

Posts: 869

Likes: 186

From: Near my truck

Quote:

Originally Posted by flowney

Here is my revised minimal ignition system diagram:

That looks more like it, and incredibly neat.

Thinking out loud :

Most of the wires will be in the engine bay, so connect E and F as both will be in the cab. (Neater.)

The 3 perfectly drawn (

) orange squares represent fuses.

The D circuit would have been used with OE points systems and some electronic systems, for info.

If A stays live during starting, then ok, no further wiring needed.

If it does not, then either A needs to be connected to B, or if C, say, has power at start, A could be connected to C.

The test light tests will shed some light. (Pun intended.

)

I also think you've already grasped it.

By the way, no need to state the AWG as those are/were for the OE system.

Your new system will be different.

Hmmm, maybe a fuse on the yellow battery supply wire would be better/easier than a fuse on the red ignition wire.

Nov 16, 2023 | 11:53 AM

#17

flowney

Thread Starter

Cargo Master

Joined: Jun 2014

Posts: 2,218

Likes: 325

From: Central Florida

Here are some clearer images of 1) my '76 Ford ignition switch blade layout and 2) details for continuity testing that same ignition switch.

I am still unclear about the prove out stage of the process. Not sure what's being proven and to whom or what.

Nov 16, 2023 | 01:08 PM

#18

dlburch

Cargo Master

Joined: Jul 2005

Posts: 2,313

Likes: 367

From: Kansas

Quote:

Originally Posted by flowney

I am still unclear about the prove out stage of the process. Not sure what's being proven and to whom or what.

all it does if provide an alternate ground path for the BRAKE warning light in the dash to test it...

Nov 16, 2023 | 02:08 PM

#19

6 by 8

Laughing Gas

Joined: Dec 2020

Posts: 869

Likes: 186

From: Near my truck

Quote:

Originally Posted by flowney

So what is the minimum that needs to be done so that this switch will support only starting and running the engine?

So what happens when the switch goes from Start to On?

Will this all work with just two wires?

I believe you have the answers to those questions.

Excellent diagrams and summary, thank you very much.

Nov 16, 2023 | 04:06 PM

#20

flowney

Thread Starter

Cargo Master

Joined: Jun 2014

Posts: 2,218

Likes: 325

From: Central Florida

Quote:

Originally Posted by dlburch

all it does if provide an alternate ground path for the BRAKE warning light in the dash to test it...

OK, thanks, that would just be a transitory signal visible on the dash. Since I don't have a dash right now, it's not a concern. I suppose that it may become relevant when I install the Dakota Digital dash much later on.

Nov 17, 2023 | 02:06 AM

#21

1TonBasecamp

Lead Driver

Joined: Jul 2017

Posts: 9,609

Likes: 1,179

From: San Jose, CA

The proof/prove out circuit is only there for testing purposes, as mentioned. That is the only reason that an ignition switch like this needs to have a ground.
All of the circuits you will be working with don’t care if the ignition switch is grounded or not, as they don’t need it.