1942 Mercury dash starter button wiring with 12v solinoid.

[signsup]

Ties into my solinoid thread, but that one has runs it's course, so starting a new inquiry. I've got the 4 position keyed Bubba ignition working and going through the 12v solinoid grounded to the firewall. Negative ground system. I'd like to add the push button starter into the mix so that I can turn the key to the run position and either start with key or use the push button.

Push button I have has only one wire and I presume this would be hot with the clips on the button grounding the switch to the dash. But if my system is now negative ground and I want to run this one wire from the botton switch to the solinoid, do I need a seperate ground to the switch? Will this one terminal switch do what I want it to do? Or should I look for a replacement swith with two leads?
Here is pic of current (no pun intended) solinoid set up. Any guideance appreciated.

[Jack E/NJ]

>>start with key or use the push button.>>


Get a 2-terminal button if you want a key and/or button start. A 1-terminal button requires mounting that solenoid with isolation from ground while holding the key in start position and pushing button at the same time.

[signsup]

That's what I was thinking. Read a forum post on either Ford tractor or large Ford truck. Any recommendation on where to look for two wire switch that will fit this home? Thanks.

[Bob C]

You could use the one wire button to activate one of the small universal relays to send power to the starter solenoid.

[rich b]

Originally Posted by Bob C

You could use the one wire button to activate one of the small universal relays to send power to the starter solenoid.

Exactly.

While leaving existing wires in place:

Connect

S on ign switch to 87 on relay

B on ign switch to 30 & 85 on relay

86 on relay to original (grounding) start button.

[Jack E/NJ]

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>> Any recommendation on where to look for two wire switch that will fit this home?>>
>>You could use the one wire button to activate one of the small universal relays to send power to the starter solenoid.>>


Yes, the relay should work as well as a 2-terminal momentary Ford button switch like this.

[signsup]

Sorry for the hand holding, but you guys have forgotten more about this stuff than I will ever learn. I've got the two wire button on order, but the original button to a relay sounds like a better option to keep the original button appearance. Is this the Ford pick up truck realy that comes up when I Google? Or is there a vendor that offers the relay referenced with these wiring connections? Thank you.

[glennpm]

Please just change the relay to a 3-wire setup as addressed in your other thread, https://www.fordbarn.com/forum/showp...1&postcount=21. No extra relay wiring and questionable wiring on your present 4-wire setup.



The #2 terminal will connect to one of the posts on the push button.

[Jack E/NJ]

He wants both button start & key start options available. The early Ford style 2-terminal button should look identical to the early Ford 1-terminal button.

[glennpm]

Originally Posted by Jack E/NJ

He wants both button start & key start options available.

I noticed that however he already has a 4-terminal solenoid setup. The only thing he needs to do with it is to trace the two wires that are attached to the S terminal. With this 4-term, the start position from the switch will allow amperage with 12V to the 4-terminal relay.

For the push button he should buy a 12V 3-terminal solenoid that is activated with a "to ground button".

[Jack E/NJ]

>>Is this the Ford pick up truck realy that comes up when I Google?>>


No. It's a universal 5-pin automotive relay. Amazon has plenty of 30-40amp 4/5 pin relays to choose from.

[Bored&Stroked]

Originally Posted by signsup

Push button I have has only one wire and I presume this would be hot with the clips on the button grounding the switch to the dash.

Just so you understand, the button you have provides a GROUND to the output wire, nothing is HOT on that button. That is why it was recommended that you purchase a normally open relay that is activated via a ground connection. The other terminals on the relay are used to provide the +12 source voltage and the +12 output voltage to the current starter solenoid that you have.

They make little wiring harnesses that are designed to plug in a relay - otherwise you will have to figure out how to mount it such that it can't short out on something around it.

There is still one question that has not been answered - have you traced the TWO wires going to the current small terminal of the solenoid to determine where BOTH of them go? You really should know this.

[signsup]

Not yet. I know one wire goes direct to the start position on the key ignition. The second wire goes into a loom and we have not identified where it comes out. Not a color coded wire, so need the voltmeter and some time. If the two wire button will do what I want to do, I have ordered one. Hopefully, by the time it arrives, I will have identified where this second wire goes. I just can't tink off the top of my head what would energize the solinoid other than the key ignition. The current push button goes into what feels like an original 6v harness.

[Jack E/NJ]

>> I just can't think off the top of my head what would energize the solinoid other than the key ignition.>>


I use the same starter solenoid. With two wires on the same energizer terminal as yours. One wire goes to the momentary 2 terminal button inside the car. The other goes to another 2 terminal button under the hood.

[rich b]

Does your original button have "start" stamped in the bezel; I used one of those 5 pin relays so I could use an original "marked" button to work a modern 4 terminal solenoid under the hood that would crank the car and feed the coil bypassing the ballast.