Idle stop wire

[vddtn1]

Does anyone know what the cylinder loking thing that is incorporated into the wire feeding the Idle stop solenoid is called, and what does it do???

 

[BigJimZ16]

Does anyone know what the cylinder loking thing that is incorporated into the wire feeding the Idle stop solenoid is called, and what does it do???

It's probably a diode to prevent the collapsing field from the solenoid coil from generating a reverse polarity voltage spike back into the electrical system. We do that all over the place on DC circuits in industry.