Grand Cherokee 2WD V8-4.7L VIN J (2004)
Starter Motor: Description and Operation
The starter motors used for both the 4.0L and the 4.7L engines available in this model are very similar, but are not interchangeable. Both starter motors
are mounted with two screws to the automatic transmission torque converter housing and are located on the right side of the engine.
Each of these starter motors incorporates several of the same features to create a reliable, efficient, compact, lightweight and powerful unit. The electric
motors of both starters feature four electromagnetic field coils wound around four pole shoes, and four brushes contact the motor commutator. Both
starter motors are rated at 1.4 kilowatts (about 1.9 horsepower) output at 12 volts.
Both of these starter motors are serviced only as a unit with their starter solenoids, and cannot be repaired. If either component is faulty or damaged, the
entire starter motor and starter solenoid unit must be replaced.
These starter motors are equipped with a planetary gear reduction (intermediate transmission) system. The planetary 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 motors for both engines are 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.
Both starter motors use an overrunning clutch and starter pinion gear unit to engage and drive a starter ring gear that is integral to the torque converter
drive plate mounted on the rear crankshaft flange.
