Solenoid question

I have a jubilee that previous owner disabled the thumb starter switch and put on a push button.
I installed new thumb switch, but no go. (Also been switched to 12 volt in past years, with a 172 engine) the solenoid has 2 large terminal, in from battery, out to starter, and one small terminal, to the thumb switch. I'm thinking the small terminal should be hot and when thumb switch is pushed, grounding it, then power goes to starter ? Currently there is no power to this terminal...bad solenoid? Or am I wrong in my thoughts...
I know this has been covered in a thread somewhere, just can't locate it...thanks in advance !!
 
When you activate the solenoid, the small terminal has to be hot, it energizes a coil, turning it into an
electromagnet, which pulls a bar into its self, that's the "click" you hear. The 2 contacts are on the
end of the bar which connect the large cable from the + terminal to the cable running to the starter
motor. Just jumper the cable from the battery to the small stud terminal, the starter should actuate. If
not, you've a solenoid problem. If the solenoid pulls in with a heavy "click" most likely the larger
contacts inside have burned and don't make good contact. If they're OK, starter motor problem. It sure
sounds like you've a problem with your starter button
 
You have the basics figured out.

If you have an original or NOS solenoid or a correct reproduction it will work as it should (and as you are expecting).

Trouble is, how that system worked was unique to dorfS of that era and "The Land of Almost Right" typically gets it WRONG.
 
Yes, the wiring you describe would have been the original way it was wired.

The factory switch would provide ground to the solenoid coil to energize it. The original also served as a neutral safety switch, so you may want to go back with the original.

Possibly the solenoid is not the original. An automotive solenoid looks the same, but it requires voltage to the small terminal and grounds through the base.

Easy enough to determine, check the small terminal with a volt meter. If it shows voltage to ground, it is the correct solenoid, and grounding the terminal should energize the starter.

If no voltage on the small terminal, try jumping the battery to the small post, that should energize it. Be sure the base is tight to ground.

Just be very careful! Remember you have no neutral safety! Be absolutely sure it is in neutral before doing anything with the starter circuit!
 
It could be he changed the solenoid when he put the push button in the dash.
Power to push button.
When you push the button it gives power to the small terminal on solenoid making it start.

This is how the car solenoids work.
Much more common at local parts stores.

It could be your thumb starter button on the trans was not bad.
He just could not find the solenoid to work with that thumb starter.
 
Going to order correct solenoid...I am thinking the current one is bad / wrong. Push button was hooked from hot junction block to small terminal...
 
As long as you use the thumb button to ground the solenoid, it should work. If the solenoid uses the mounting
bracket as a ground, it will take some engineering to isolate it.
 

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