Starter Motor: Description and Operation

The 2.5L starter is mounted with two bolts to the clutch housing on the right side of the engine. The 4.7L automatic transmission starter motor is mounted with two bolts to the torque converter housing on the left side of the engine. The starter motors for all of the remaining engine and transmission combinations are mounted with one bolt, a stud and a nut to the clutch or convertor housing, and are located on the left side of the engine.

The electric motors of both starters have four brushes contacting the motor commutator. The 2.5L starter motor uses four permanent magnets for the field poles, while the other starter motors feature four electromagnetic field coils wound around four pole shoes.

The starter motors are serviced only as a unit with starter solenoids, and cannot be repaired. If either component is faulty or damaged, the entire starter motor and starter solenoid unit must be replaced.

The starter motor is equipped with a gear reduction (intermediate transmission) system. The gear reduction system consists of a gear that is integral to the output end of the electric motor armature shaft that is in continual engagement with a larger gear that is splined to the input end of the starter pinion gear shaft. This feature makes it possible to reduce the dimensions of the starter. At the same time, it allows higher armature rotational speed, and delivers increased torque through the starter pinion gear to the starter ring gear.

The starter motor is activated by an integral heavy duty starter solenoid switch mounted to the overrunning clutch housing. This electromechanical switch connects and disconnects the feed of battery voltage to the starter motor, and actuates a shift fork that engages and disengages the starter pinion gear with the starter ring gear.

The starter motor uses an overrunning clutch and starter pinion gear unit to engage and drive the gears on the flywheel (or flywheel ring gear).