F 350 2WD Pickup V8-460 7.5L VIN G EFI (1997)
Starter Solenoid: Description and Operation
The starter solenoid performs two functions. It shifts the starter drive pinion into engagement with the flywheel ring gear and connects the starter motor
to the positive side of the battery.
The drive pinion is shifted through a lever which is connected to the solenoid plunger. The electrical circuit between the starter B- and M-terminals is
closed by a contact disc which is also attached to the solenoid plunger.
Movement of the plunger is the result of a magnetic field generated by the pull-in and hold-in windings contained in the solenoid.
When the key is turned to START current flows through both solenoid windings. This creates a magnetic field strong enough to pull in the plunger,
shifting the overrunning clutch and drive pinion into mesh with the flywheel ring gear. As the plunger nears bottom, it strikes the contact disc and forces
the disc against the starter motor contacts. This completes the battery circuit, and the starter motor operates.
When the contact disc closes the contacts, the pull-in winding loses its effect due to the voltage being equal at both ends of the winding. The hold-in coil
continues to hold the plunger in the closed position and reduces the current needed by the solenoid. When the ignition switch is released, the current to
the solenoid stops. The springs within the solenoid open the starter motor circuit contacts and shift the clutch and pinion assembly to the at-rest position.
