Solenoid confusion

[DHW]

Just finished wiring my 960, but now have questions about my solenoid left over from the
previous wiring job.

The solenoid that I have has 2 terminal plus "I" terminal and no "S" terminal. This one is
stumping me considering most diagrams show the starter button going to the S terminal.


What's the difference between a S & I terminal as far as connections to the starter button
is concerned?


Thanks guys

Dan

 

[DHW]

This is a 12 volt ,alt 1 wire conversion

 

[Bob]

(quoted from post at 21:03:10 07/02/19) Just finished wiring my 960, but now have questions about my solenoid left over from the
previous wiring job.

The solenoid that I have has 2 terminal plus "I" terminal and no "S" terminal. This one is
stumping me considering most diagrams show the starter button going to the S terminal.


What's the difference between a S & I terminal as far as connections to the starter button
is concerned?

Thanks guys

Dan

It seems solenoid manufacturers mold one universal "case" for these solenoids, and the only time the markings are correct is when the solenoid is a "fender-mount" starter solenoid such as was used on older Ford vehicles.


There are several varieties of these solenoids, including the "isolated base" type, in which BOTH ends of the coil are "brought out" through the two little studs, and even thse typically use the same "case" with the "S" and "I" markings.


Originally "S" was "START" and "I" was "I"gnition, and used to bypass the ballast resistor ahead of the coil for a hotter spark during cranking.

If your solenoid has two large terminals, and only ONE small terminal, and it's marked "I", ignore the case marking, it's the "S" terminal. NO way for a starter solenoid to work with just an "I" terminal.

 

[George by Geneva, NY]

I agree with Bob, only way to be sure is to verify with meter. I had a new brand name solenoid that had S and I molded but the pull in coil was wired to the 2 small terminals.

 

[JMOR]

(quoted from post at 07:57:16 07/03/19) I agree with Bob, only way to be sure is to verify with meter. I had a new brand name solenoid that had S and I molded but the pull in coil was wired to the 2 small terminals.

only" is bad word......just apply battery power in various ways and you can determine what solenoid you have.

 

[JDEM]

I was just in the middle of fixing the wiring on my NAA Ford with a one-small-post starter relay. I don't have a lot of experience with Ford tractor OEM wiring so it kind of threw me at first. The relay gets energized by a ground signal, not a hot signal. So the opposite of any solenoid/relay you will find from any modern car or truck. I was digging through my junk-box that has over 30 relays and solenoids. Most had the I and S twin small terminals (ignition bypass and start). I finally found one with two small posts that is unmarked and isolated. That is - to energize - one small terminal goes to ground and the other to hot to energize. So I hooked one small terminal to the hot battery post and the other to the starter button and it all works fine. The OEM solenoid/relay was hot all the time and required a ground signal to the small terminal to energize.

 

[sunbeam]

If you have a ford tractor with the starter button on the trans and the solenoid has continuity from the S terminal to the base you have the wrong one.