Dodge Durango (DN). Manual — part 43
rotate counterclockwise, the action causes the rollers
to roll in the same direction as the race, aided by the
pushing of the springs. As the rollers try to move in
the same direction as the inner race, they are
wedged between the inner and outer races due to the
design of the cam. In this condition, the clutch is
locked and acts as one unit.
PLANETARY GEARSET
DESCRIPTION
The planetary gearsets (Fig. 58) are designated as
the front, rear, and overdrive planetary gear assem-
blies and located in such order. A simple planetary
gearset consists of three main members:
• The sun gear which is at the center of the sys-
tem.
• The planet carrier with planet pinion gears
which are free to rotate on their own shafts and are
in mesh with the sun gear.
• The annulus gear, which rotates around and is
in mesh with the planet pinion gears.
NOTE: The number of pinion gears does not affect
the gear ratio, only the duty rating.
OPERATION
With any given planetary gearset, several condi-
tions must be met for power to be able to flow:
• One member must be held.
• Another member must be driven or used as an
input.
• The third member may be used as an output for
power flow.
• For direct drive to occur, two gear members in
the front planetary gearset must be driven.
NOTE: Gear ratios are dependent on the number of
teeth on the annulus and sun gears.
BANDS
DESCRIPTION
KICKDOWN (FRONT) BAND
The kickdown, or “front”, band (Fig. 59) holds the
common sun gear of the planetary gear sets. The
front (kickdown) band is made of steel, and faced on
its inner circumference with a friction–type lining.
One end of the band is anchored to the transmission
case, and the other is acted on with a pushing force
by a servo piston. The front band is a single–wrap
design (the band does not completely encompass/
wrap the drum that it holds).
LOW/REVERSE (REAR) BAND
The low/reverse band, or “rear”, band (Fig. 60) is
similar in appearance and operation to the front
band.
OPERATION
KICKDOWN (FRONT) BAND
The kickdown band holds the common sun gear of
the planetary gear sets by applying and holding the
front clutch retainer, which is splined to the sun gear
driving shell, and in turn splined directly to the sun
Fig. 57 Overrunning Clutch
1 – OUTER RACE (CAM)
2 – ROLLER
3 – SPRING
4 – SPRING RETAINER
5 – INNER RACE (HUB)
Fig. 58 Planetary Gearset
1 – ANNULUS GEAR
2 – SUN GEAR
3 – PLANET CARRIER
4 – PLANET PINIONS (4)
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DESCRIPTION AND OPERATION (Continued)
gear. The application of the band by the servo is typ-
ically done by an apply lever and link bar.
LOW/REVERSE (REAR) BAND
The rear band holds the rear planet carrier sta-
tionary by being mounted around and applied to the
low/reverse drum.
SERVOS
DESCRIPTION
KICKDOWN (FRONT) SERVO
The kickdown servo (Fig. 61) consists of a two–land
piston with an inner piston, a piston rod and guide,
and a return spring. The dual–land piston uses seal
rings on its outer diameters and an O–ring for the
inner piston.
LOW/REVERSE (REAR) SERVO
The rear (low/reverse) servo consists of a single
stage or diameter piston and a spring loaded plug.
The spring is used to cushion the application of the
rear (low/reverse) band.
OPERATION
KICKDOWN (FRONT) SERVO
The application of the piston is accomplished by
applying pressure between the two lands of the pis-
ton. The pressure acts against the larger lower land
to push the piston downward, allowing the piston rod
to extend though its guide against the apply lever.
Release of the servo at the 2–3 upshift is accom-
plished by a combination of spring and line pressure,
acting on the bottom of the larger land of the piston.
The small piston is used to cushion the application of
the band by bleeding oil through a small orifice in
the larger piston. The release timing of the kickdown
servo is very important to obtain a smooth but firm
Fig. 59 Front Band
1 – FRONT BAND
2 – TRANSMISSION HOUSING
Fig. 60 Rear Band
1 – REAR BAND
2 – BAND LINK
Fig. 61 Front Servo
1 – VENT
2 – INNER PISTON
3 – PISTON
4 – SPRING
5 – RELEASE PRESSURE
6 – APPLY PRESSURE
7 – PISTON ROD
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42/44RE AUTOMATIC TRANSMISSION
21 - 39
DESCRIPTION AND OPERATION (Continued)
shift. The release has to be very quick, just as the
front clutch application is taking place. Otherwise,
engine runaway or a shift hesitation will occur. To
accomplish this, the band retains its holding capacity
until the front clutch is applied, giving a small
amount of overlap between them.
LOW/REVERSE (REAR) SERVO
While in the de-energized state (no pressure
applied), the piston is held up in its bore by the pis-
ton spring. The plug is held down in its bore, in the
piston, by the plug spring. When pressure is applied
to the top of the piston, the plug is forced down in its
bore, taking up any clearance. As the piston moves, it
causes the plug spring to compress, and the piston
moves down over the plug. The piston continues to
move down until it hits the shoulder of the plug and
fully applies the band. The period of time from the
initial application, until the piston is against the
shoulder of the plug, represents a reduced shocking
of the band that cushions the shift.
GEARSHIFT MECHANISM
DESCRIPTION
The gear shift mechanism provides six shift posi-
tions which are:
• Park (P)
• Reverse (R)
• Neutral (N)
• Drive (D)
• Manual second (2)
• Manual low (1)
OPERATION
Manual low (1) range provides first gear only.
Overrun braking is also provided in this range. Man-
ual second (2) range provides first and second gear
only.
Drive range provides first, second third and over-
drive fourth gear ranges. The shift into overdrive
fourth gear range occurs only after the transmission
has completed the shift into D third gear range. No
further movement of the shift mechanism is required
to complete the 3-4 shift.
The fourth gear upshift occurs automatically when
the overdrive selector switch is in the ON position.
No upshift to fourth gear will occur if any of the fol-
lowing are true:
• The transmission fluid temperature is below 10°
C (50° F) or above 121° C (250° F).
• The shift to third is not yet complete.
• Vehicle speed is too low for the 3–4 shift to
occur.
• Battery temperature is below –5° C (23° F).
CONVERTER DRAINBACK VALVE
DESCRIPTION
The drainback valve is located in the transmission
cooler outlet (pressure) line.
OPERATION
The valve prevents fluid from draining from the
converter into the cooler and lines when the vehicle
is shut down for lengthy periods. Production valves
have a hose nipple at one end, while the opposite end
is threaded for a flare fitting. All valves have an
arrow (or similar mark) to indicate direction of flow
through the valve.
POWERTRAIN CONTROL MODULE (PCM)
DESCRIPTION
The Powertrain Control Module (PCM) is located
in the engine compartment (Fig. 62). The PCM is
referred to as JTEC.
OPERATION
The PCM operates the fuel system. The PCM is a
pre-programmed, triple microprocessor digital com-
puter. It regulates ignition timing, air-fuel ratio,
emission control devices, charging system, certain
transmission features, speed control, air conditioning
compressor clutch engagement and idle speed. The
PCM can adapt its programming to meet changing
operating conditions.
Fig. 62 PCM Location
1 – RIGHT FRONT FENDER
2 – PCM MOUNTING BOLTS (3)
3 – 32–WAY CONNECTORS (3)
4 – COVER
5 – POWERTRAIN CONTROL MODULE (PCM)
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DESCRIPTION AND OPERATION (Continued)
The PCM receives input signals from various
switches and sensors. Based on these inputs, the
PCM regulates various engine and vehicle operations
through different system components. These compo-
nents are referred to as Powertrain Control Module
(PCM) Outputs. The sensors and switches that pro-
vide inputs to the PCM are considered Powertrain
Control Module (PCM) Inputs.
The PCM adjusts ignition timing based upon
inputs it receives from sensors that react to: engine
rpm, manifold absolute pressure, engine coolant tem-
perature, throttle position, transmission gear selec-
tion (automatic transmission), vehicle speed and the
brake switch.
The PCM adjusts idle speed based on inputs it
receives from sensors that react to: throttle position,
vehicle speed, transmission gear selection, engine
coolant temperature and from inputs it receives from
the air conditioning clutch switch and brake switch.
Based on inputs that it receives, the PCM adjusts
ignition coil dwell. The PCM also adjusts the gener-
ator charge rate through control of the generator
field and provides speed control operation.
NOTE: PCM Inputs:
• A/C request (if equipped with factory A/C)
• A/C select (if equipped with factory A/C)
• Auto shutdown (ASD) sense
• Battery temperature
• Battery voltage
• Brake switch
• CCD bus (+) circuits
• CCD bus (-) circuits
• Camshaft position sensor signal
• Crankshaft position sensor
• Data link connection for DRB scan tool
• Engine coolant temperature sensor
• Fuel level
• Generator (battery voltage) output
• Ignition circuit sense (ignition switch in on/off/
crank/run position)
• Intake manifold air temperature sensor
• Leak detection pump (switch) sense (if equipped)
• Manifold absolute pressure (MAP) sensor
• Oil pressure
• Output shaft speed sensor
• Overdrive/override switch
• Oxygen sensors
• Park/neutral switch (auto. trans. only)
• Power ground
• Sensor return
• Signal ground
• Speed control multiplexed single wire input
• Throttle position sensor
• Transmission governor pressure sensor
• Transmission temperature sensor
• Vehicle speed inputs from ABS or RWAL system
NOTE: PCM Outputs:
• A/C clutch relay
• Auto shutdown (ASD) relay
• CCD bus (+/-) circuits for: speedometer, voltme-
ter, fuel gauge, oil pressure gauge/lamp, engine temp.
gauge and speed control warn. lamp
• Data link connection for DRB scan tool
• EGR valve control solenoid (if equipped)
• EVAP canister purge solenoid
• Five volt sensor supply (primary)
• Five volt sensor supply (secondary)
• Fuel injectors
• Fuel pump relay
• Generator field driver (-)
• Generator field driver (+)
• Generator lamp (if equipped)
• Idle air control (IAC) motor
• Ignition coil
• Leak detection pump (if equipped)
• Malfunction indicator lamp (Check engine lamp).
Driven through CCD circuits.
• Overdrive indicator lamp (if equipped)
• Radiator cooling fan (2.5L engine only)
• Speed control vacuum solenoid
• Speed control vent solenoid
• Tachometer (if equipped). Driven through CCD
circuits.
• Transmission convertor clutch circuit
• Transmission 3–4 shift solenoid
• Transmission relay
• Transmission temperature lamp (if equipped)
• Transmission variable force solenoid
ELECTRONIC GOVERNOR
DESCRIPTION
Governor pressure is controlled electronically. Com-
ponents used for governor pressure control include:
• Governor body
• Valve body transfer plate
• Governor pressure solenoid valve
• Governor pressure sensor
• Fluid temperature thermistor
• Throttle position sensor (TPS)
• Transmission speed sensor
• Powertrain control module (PCM)
GOVERNOR PRESSURE SOLENOID VALVE
The solenoid valve is a duty-cycle solenoid which
regulates the governor pressure needed for upshifts
and downshifts. It is an electro-hydraulic device
located in the governor body on the valve body trans-
fer plate (Fig. 63).
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DESCRIPTION AND OPERATION (Continued)
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