Chrysler Pacifica. Manual — part 440
the rear wheels. It also allows the braking system to
control the braking behavior as a two wheel drive
(2WD) vehicle.
The overrunning clutch housing has a separate oil
sump and is filled independently from the differen-
tial. The fill plug is located on the side of the over-
running clutch case. When filling the overrunning
clutch with lubricant use Mopar
t ATF+4.
The differential assembly contains a conventional
open differential with hypoid ring gear and pinion
gear set. The hypoid gears are lubricated by SAE
75W-90 Mopar
t Gear and Axle Lubricant.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - REAR DRIVELINE
MODULE NOISE
Different sources can be the cause of noise that the
rear driveline module assembly is suspected of mak-
ing. Refer to the following causes for noise diagnosis.
DRIVELINE MODULE ASSEMBLY NOISE
The most important part of driveline module ser-
vice is properly identifying the cause of failures and
noise complaints. The cause of most driveline module
failures is relatively easy to identify. The cause of
driveline module noise is more difficult to identify.
If vehicle noise becomes intolerable, an effort
should be made to isolate the noise. Many noises that
are reported as coming from the driveline module
may actually originate at other sources. For example:
• Tires
• Road surfaces
• Wheel bearings
• Engine
• Transmission
• Exhaust
• Propeller shaft (vibration)
• Vehicle body (drumming)
Driveline module noises are normally divided into
two categories: gear noise or bearing noise. A thor-
ough and careful inspection should be completed to
determine the actual source of the noise before
replacing the driveline module.
Fig. 1 Driveline Module Section
1 - INPUT FLANGE
7 - BI-DIRECTIONAL OVERRUNNING
CLUTCH (BOC)
13 - PLUG-OVERRUNNING CLUTCH
HOUSING DRAIN
2 - FLANGE NUT
8 - VISCOUS COUPLER
14 - SNAP RING
3 - WASHER
9 - SHIM (SELECT)
15 - BEARING
4 - SHIELD
10 - O-RING
16 - OVERRUNING CLUTCH HOUSING
5 - VENT
11 - DIFFERENTIAL ASSEMBLY
17 - SEAL-INPUT FLANGE
6 - WASHER
12 - PLUG-DIFFERENTIAL FILL
18 - O-RING
CS
REAR DRIVELINE MODULE
3 - 29
REAR DRIVELINE MODULE (Continued)
The rubber mounting bushings help to dampen-out
driveline module noise when properly installed.
Inspect to confirm that no metal contact exists
between the driveline module case and the body or
suspension cradle. The complete isolation of noise to
one area requires expertise and experience. Identify-
ing certain types of vehicle noise baffles even the
most capable technicians. Often such practices as:
• Increase tire inflation pressure to eliminate tire
noise.
• Listen for noise at varying speeds with different
driveline load conditions
• Swerving the vehicle from left to right to detect
wheel bearing noise.
All driveline module assemblies produce noise to a
certain extent. Slight carrier noise that is noticeable
only at certain speeds or isolated situations should be
considered normal. Carrier noise tends to peak at a
variety of vehicle speeds. Noise is NOT ALWAYS an
indication of a problem within the carrier.
TIRE NOISE
Tire noise is often mistaken for driveline module
noise. Tires that are unbalanced, worn unevenly or
are worn in a saw-tooth manner are usually noisy.
They often produce a noise that appears to originate
in the driveline module.
Tire noise changes with different road surfaces, but
driveline module noise does not. Inflate all four tires
with approximately 20 psi (138 kPa) more than the
recommended inflation pressure (for test purposes
only). This will alter noise caused by tires, but will
not affect noise caused by the differential. Rear axle
noise usually ceases when coasting at speeds less
than 30 mph (48 km/h); however, tire noise contin-
ues, but at a lower frequency, as the speed is
reduced.
After test has been completed lower tire pressure
back to recommended pressure.
GEAR NOISE (DRIVE PINION AND RING GEAR)
Abnormal gear noise is rare and is usually caused
by scoring on the ring gear and drive pinion. Scoring
is the result of insufficient or incorrect lubricant in
the carrier housing.
Abnormal gear noise can be easily recognized. It
produces a cycling tone that will be very pronounced
within a given speed range. The noise can occur dur-
ing one or more of the following drive conditions:
• Drive
• Road load
• Float
• Coast
Abnormal gear noise usually tends to peak within
a narrow vehicle speed range or ranges. It is usually
more pronounced between 30 to 40 mph (48 to 64
km/h) and 50 to 60 mph (80 to 96 km/h). When objec-
tionable gear noise occurs, note the driving condi-
tions and the speed range.
BEARING NOISE (DRIVE PINION AND
DIFFERENTIAL)
Defective bearings produce a rough growl that is
constant in pitch and varies with the speed of vehi-
cle. Being aware of this will enable a technician to
separate bearing noise from gear noise.
Drive pinion bearing noise that results from defec-
tive or damaged bearings can usually be identified by
its constant, rough sound. Drive pinion front bearing
is usually more pronounced during a coast condition.
Drive pinion rear bearing noise is more pronounced
during a drive condition. The drive pinion bearings
are rotating at a higher rate of speed than either the
differential side bearings or the axle shaft bearing.
Differential side bearing noise will usually produce
a constant, rough sound. The sound is much lower in
frequency than the noise caused by drive pinion bear-
ings.
Bearing noise can best be detected by road testing
the vehicle on a smooth road (black top). However, it
is easy to mistake tire noise for bearing noise. If a
doubt exists, the tire treads should be examined for
irregularities that often causes a noise that resem-
bles bearing noise.
ENGINE AND TRANSMISSION NOISE
Sometimes noise that appears to be in the driv-
eline module assembly is actually caused by the
engine or the transmission. To identify the true
source of the noise, note the approximate vehicle
speed and/or RPM when the noise is most noticeable.
Stop the vehicle next to a flat brick or cement wall
(this will help reflect the sound). Place the transaxle
in NEUTRAL. Accelerate the engine slowly up
through the engine speed that matches the vehicle
speed noted when the noise occurred. If the same
noise is produced, it usually indicates that the noise
is being caused by the engine or transaxle.
DIAGNOSIS AND TESTING - REAR DRIVELINE
MODULE OPERATION
Driveline
module
operation
requires
relatively
straight-forward diagnosis. Refer to the following
chart:
3 - 30
REAR DRIVELINE MODULE
CS
REAR DRIVELINE MODULE (Continued)
DRIVELINE MODULE DIAGNOSIS CHART
CONDITION
POSSIBLE CAUSES
CORRECTION
Rear wheels not overrunning
1) Bi-directional overrunning clutch
failure
1) Replace overrunning clutch
components as required
No AWD in forward or reverse
directions, propeller shaft
turning
1) Bi-directional overrunning clutch
failure
1) Replace overrunning clutch
components as required
2) Viscous coupling failure
2) Replace viscous coupling
3) Rear differential failure
3) Replace the rear differential
assembly
No AWD in forward or reverse
directions, propeller shaft not
turning
1) Power transfer unit failure.
1) Replace power transfer unit
components as necessary
Vibration at all speeds,
continuous torque transfer
1) Mis-matched tires, worn tires on front
axle.
1) Replace worn or incorrect
(mis-matched) tires with same
make and size
REMOVAL
NOTE:
Rear
suspension
and
drivetrain
design
require this procedure to be performed on a “drive-
on” hoist, as the front and rear suspension needs
to be compressed to ride height to facilitate rear
halfshaft removal.
(1) Raise vehicle on hoist.
(2) Drain differential lubricant to prevent fluid
spillage upon removal.(Refer to 3 - DIFFERENTIAL
&
DRIVELINE/REAR
DRIVELINE
MODULE/
FLUID - STANDARD PROCEDURE). If disassembly
of driveline module is taking place, drain overrun-
ning clutch housing fluid as well.(Refer to 3 - DIF-
FERENTIAL
&
DRIVELINE/REAR
DRIVELINE
MODULE/FLUID - STANDARD PROCEDURE)
(3) Place vehicle on drive-on hoist in Park.
(4) Remove exhaust system center hanger (at pro-
peller shaft bearing/support).
(5) Disconnect exhaust system at rear-most hanger
and lower.
(6) Lower exhaust system at least 254 mm (10 in.).
Support system with suitable wire or rope.
(7) Index propeller shaft and rear driveline module
flanges using paint mark, chalk, etc. for installation
reference.
(8) Remove three (3) propeller shaft-to-driveline
module bolts. Do not attempt to disconnect shaft
from module, as it will be disconnected upon driv-
eline module removal.
(9) Support driveline module with transmission
jack (or equivalent). (Fig. 2)
(10) Using suitable screwdriver, partially dislodge
halfshafts from differential. Install Tool 9099 to pro-
tect seal upon disassembly (Fig. 3).
(11) Remove three (3) rear driveline module-to-
crossmember bolts (Fig. 4) (Fig. 5).
(12) Lower driveline module assembly just enough
to facilitate removal of halfshafts from differential.
Make sure Tool 9099 engages seal.
(13) Disconnect propeller shaft from driveline mod-
ule and secure to exhaust system or support with
jack stand (Fig. 6).
CAUTION: Do not allow the propeller shaft to hang
from the vehicle unsupported. Damage may occur
to the joint, boot, and center bearing from over-an-
gulation.
Fig. 2 Support Module with Jack
1 - DRIVELINE MODULE
2 - TRANSMISSION JACK
CS
REAR DRIVELINE MODULE
3 - 31
REAR DRIVELINE MODULE (Continued)
(14) Remove driveline module assembly.
Fig. 3 Install Seal Protector
1 - HALFSHAFT
2 - SEAL PROTECTOR
Fig. 4 Module Mounting Bolt
1 - BOLT
2 - DRIVELINE MODULE
Fig. 5 Module Mounting Bolts
1 - BOLT (2)
2 - DRIVELINE MODULE
Fig. 6 Secure Propeller Shaft to Exhaust
1 - PROPELLER SHAFT
2 - EXHAUST SYSTEM
3 - STRAP
3 - 32
REAR DRIVELINE MODULE
CS
REAR DRIVELINE MODULE (Continued)
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