Function

Function

Engaging the pinion




When the ignition key is turned to position III, the starter motor relay (2/35) receives power at terminal 86. If the immobilizer check is OK, then the engine control module (ECM) grounds the relay at terminal 85 and the relay is activated. Control solenoid terminal 6/25:2 is powered from relay terminal 87. This creates a magnetic field in hold-in and pull-in winding. This moves the moving steel core. When the core shifts a lever, fixed in the end of the core, presses the starter motor pinion to engage in the ring gear on the flywheel/flange.
The pull-in winding is grounded through the rotor and carbon brushes. This ground connection is lost when the moving switches close the circuit and the current passes from the solenoid to the starter motor.

Planetary train




When the starter motor rotates, the sun wheel rotates clockwise. The planetary gears, which are constantly engaged with the sun wheel and ring wheel, rotate counter-clockwise. As the ring wheel is secured, the planetary gears are forced to circle around the sun wheel clockwise. The planetary gears rotate more slowly than the sun wheel. It is the clockwise rotation of the planetary gears which drives the pinion. The speed reduction that occurs between the sun gear and the planetary gear, results in greater torque. This means that a smaller and lighter starter motor can be used.

Starting the engine




When the moving steel cores for the solenoids reach their limit position the moving switches break the circuit with the fixes switches and the pull-in winding is disconnected. The hold-in winding keeps the switches closed. The current now passes through the positive carbon brushes and the armature winding. Grounding is carried out through the negative carbon brushes. This current creates a magnetic field in the rotor, which starts the rotor rotating. When the rotor rotates, the magnetic field is generated continuously depending on how the commutator and the windings are organized on the rotor. This allows the rotor to continue rotating.
When the ignition key is released the starter motor relay is deactivated and the circuit for the hold in winding is broken. Then the return spring for the solenoid pulls the pinion back, at the same time as the fixed and moving switches separate and the current to the starter motor is broken.

Park / neutral position (PNP) function
See Design and Function, Immobilizer.