Dodge 2000 DURANGO Service Manual page 270

8B - 2 STARTING SYSTEMS
DESCRIPTION AND OPERATION (Continued)
OPERATION
The starting system components form two separate
circuits. A high-amperage feed circuit that feeds the
starter motor between 150 and 350 amperes, and a
low-amperage control circuit that operates on less
than 20 amperes. The high-amperage feed circuit
components include the battery, the battery cables,
the contact disc portion of the starter solenoid, and
the starter motor. The low-amperage control circuit
components include the ignition switch, the park/
neutral position switch, the starter relay, the electro-
magnetic windings of the starter solenoid, and the
connecting wire harness components.
Battery voltage is supplied through the low-amper-
age control circuit to the coil battery terminal of the
starter relay when the ignition switch is turned to
the momentary Start position. The park/neutral posi-
tion switch is installed in series between the starter
relay coil ground terminal and ground. This normally
open switch prevents starter motor operation unless
the automatic transmission gear selector is in the
Neutral or Park positions.
When the starter relay coil is energized, the nor-
mally open relay contacts close. The relay contacts
connect the relay common feed terminal to the relay
normally open terminal. The closed relay contacts
energize the starter solenoid coil windings.
The energized solenoid pull-in coil pulls in the sole-
noid plunger. The solenoid plunger pulls the shift
lever in the starter motor. This engages the starter
overrunning clutch and pinion gear with the starter
ring gear on the automatic transmission torque con-
verter or torque converter drive plate.
As the solenoid plunger reaches the end of its
travel, the solenoid contact disc completes the high-
amperage starter feed circuit and energizes the sole-
noid plunger hold-in coil. Current now flows between
the solenoid battery terminal and the starter motor,
energizing the starter.
Once the engine starts, the overrunning clutch pro-
tects the starter motor from damage by allowing the
starter pinion gear to spin faster than the pinion
shaft. When the driver releases the ignition switch to
the On position, the starter relay coil is de-energized.
This causes the relay contacts to open. When the
relay contacts open, the starter solenoid plunger
hold-in coil is de-energized.
When the solenoid plunger hold-in coil is de-ener-
gized, the solenoid plunger return spring returns the
plunger to its relaxed position. This causes the con-
tact disc to open the starter feed circuit, and the shift
lever to disengage the overrunning clutch and pinion
gear from the starter ring gear.
Following are general descriptions of the major
components in the starting system.
STARTER MOTOR
DESCRIPTION
The starter motors used for the 4.7L engines are
not interchangeable with the starter motors used for
the other available engines for this model. The
starter motors used for all 5.2L and 5.9L engines
available in this model are interchangeable.
The 4.7L engine starter motor is mounted with two
screws to the automatic transmission torque con-
verter housing on the left side of the engine. The
starter motors for all of the remaining engines are
mounted with one screw, a stud and a nut to the
automatic transmission torque converter housing and
are also located on the left 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 have four brushes contacting
the motor commutator. These starter motors use four
electromagnetic field coils wound around four pole
shoes. The starter motors are rated at 1.4 kilowatts
(about 1.9 horsepower) output at 12 volts.
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.
OPERATION
These starter motors are equipped with a gear
reduction (intermediate transmission) system. The
gear reduction system consists of a gear that is inte-
gral 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 all 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.
These 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 con-
verter or torque converter drive plate mounted on the
rear crankshaft flange.
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