What is the Difference Between 3 and 4 Terminal Solenoids

Updated 08/06/2025 | Published 06/06/2015

Products Featured in This Question

Starter Solenoid - SPST - 12 Volt - 100 Amp - Continuous Duty - Insulated - UL Listed

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$36.74

Starter Solenoid - SPST - 12 Volt - 100 Amp - Continuous Duty - Grounded

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$33.90

Question:

what is the difference between a solenoid that has 1 small terminal in the front from 2 terminals.the on for my 52 dodge had one and i bought one that has 2.should i switch it ?

asked by: Daniel

Expert Reply:

A solenoid that has 3 terminals total such as # PK5231201 grounds through the mounting hardware so it must be attached to a clean and corrosion free bare metal surface (if not otherwise internally grounded). A 4 terminal solenoid such as # PK5230701 requires a separate ground wire. You could use either style provided it is rated properly for your application.

expert reply by: Michael H

5/2/2025

Some 4 post solenoids use where they mount as you described a 3 post. The extra small post gets power when solenoid is energized, sending power to the starter and the extra small post.

Jameson C.

5/12/2025

@D I believe yo are talking about a start solenoid for a vehicle?

Tom H.

8/6/2025

I have a four prong starter solenoid and the Polaris shop give me a three prong for my four wheeler. What do I do with the extra negative wire

Jameson C.

8/6/2025

@TomH This would be best answered by the Polaris shop who sold you the solenoid but there's a pretty good chance you'd just need to run that extra negative wire to the mounting hardware.