SOLENOID REPLACEMENT

[GENE DERRINGER]

I am replacing a 3 post solenoid with a four post - couldn't find a three post. Do I need to run a ground wire to the extra post? Thanks for any advice you can give.

 

[Jim.ME]

(quoted from post at 08:58:03 11/12/21) I am replacing a 3 post solenoid with a four post - couldn't find a three post. Do I need to run a ground wire to the extra post? Thanks for any advice you can give.

Maybe, maybe not. Not enough info given. What is the brand and part number of the solenoid? What is it going on? Is the wiring original or has it been modified?

 

[Indiana Ken]

This site has 3 post starter solenoids. Click on Tractor Parts, choose a tractor brand, click on electric systems. P/N 8N11450 is a 3 post start solenoid for a 8N Ford. Power to the pull in coil is supplied (internally) from one of the two large terminals - this terminal is connected to the battery. The small terminal is connected to ground through the starter switch - when you hear the click the two larger terminals are connected together connecting the battery to the starter.

Four post solenoids have two large terminals that get connected to the battery and the starter, same as above. The two smaller terminals can be used for the pull in coil - suppling power to the pull in coil will cause the click. If this is the case with your solenoid - typically one terminal is supplied battery power from a starter switch and the other terminal is connected to ground.

There is another type of four post solenoid that uses one of the small terminals to bypass the ignition resistor - this was more of an automotive application than for tractors. And there may be other types out there - I did not see where you stated what you have.

 

[wore out]

(quoted from post at 05:58:03 11/12/21) I am replacing a 3 post solenoid with a four post - couldn't find a three post. Do I need to run a ground wire to the extra post? Thanks for any advice you can give.

As others told you, we need to know the make and part number of the solenoid to be sure, there are at least NINE possible internal configurations for common starter solenoids.

 

[John T]

Some of the older starter solenoids had but ONE small S input terminal and used case/frame/ground as the activation coil return. Others have TWO small terminals with the activation coil end to end NOT the case/frame. If that's the case and SUBJECT TO INTERNAL WIRING AND CONFIGURATION you MIGHT indeed use one as + and other - and use frame ground for the minus on a Neg ground system. However its impossible to say absent the diagram SO NO WARRANTY Ohm it out !!!!!!!

John T

 

[GENE DERRINGER]

Thanks to all for your help and advice.

 

[ZehnX]

Hey Wore Out, this schematic is being posted all over, thanks for the contribution!
Do you have a line on which part number line up to each type?

 

[JMOR]

(quoted from post at 21:46:16 11/22/21) Hey Wore Out, this schematic is being posted all over, thanks for the contribution!
Do you have a line on which part number line up to each type?

ven for same circuit configuration, the mounting brackets can be different, for example curved to mount on round barrel of starter and flat to mount on a flat surface, thus different part numbers. Furthermore, the same part (electrically and mechanically) may have a half dozen part numbers due to differing manufacturers.

Oh, never mind, you addressed that question to wore out.

This post was edited by JMOR on 11/24/2021 at 06:57 am.