Description & Operation
When ignition switch is turned to START position, battery voltage is applied to Park/Neutral Position (PNP) switch. Current passes through PNP switch then on to starter relay coil only when shift lever is in Park or Neutral position. When starter relay is energized, current passes on to starter solenoid "S" terminal. This causes solenoid plunger to move shift lever, which engages pinion with engine flywheel ring gear. Movement of plunger also closes main solenoid contacts, applying battery voltage to starter motor. See Fig 1 .
When engine starts, pinion will overrun, protecting armature from excessive speed and flywheel from damage. When ignition switch is released, plunger return spring disengages pinion.
Starters with PG designation have a pinion that is driven by a 5:1 gear reduction system. PG starters should not be disassembled, and are serviceable only by complete replacement.
Starters with 28MT designation, used on diesel engines, have a pinion that is driven by a gear reduction system.