four wheel drive CHRYSLER CARAVAN 2002 Owner's Manual

TURBOCHARGER SYSTEM
DESCRIPTION
CAUTION: The turbocharger is a performance part
and must not be tampered with. The wastegate
bracket is an integral part of the turbocharger. Tam-
pering with the wastegate components can reduce
durability by increasing cylinder pressure and ther-
mal loading due to incorrect inlet and exhaust man-
ifold pressure. Poor fuel economy and failure to
meet regulatory emissions laws may result. Increas-
ing the turbocharger boost WILL NOT increase
engine power.
The turbocharger is an exhaust-driven super-
charger which increases the pressure and density of
the air entering the engine. With the increase of air
entering the engine, more fuel can be injected into
the cylinders, which creates more power during com-
bustion.
The turbocharger assembly consists of four (4)
major component systems (Fig. 1) (Fig. 2):
²Turbine section
²Compressor section
²Bearing housing
²Wastegate
OPERATION
Exhaust gas pressure and energy drive the tur-
bine, which in turn drives a centrifugal compressor
that compresses the inlet air, and forces the air into
the engine through the charge air cooler and plumb-
ing. Since heat is a by-product of this compression,
the air must pass through a charge air cooler to cool
the incoming air and maintain power and efficiency.
Increasing air flow to the engine provides:
²Improved engine performance
²Lower exhaust smoke density
²Improved operating economy
²Altitude compensation
²Noise reduction.
The turbocharger also uses a wastegate (Fig. 3),
which regulates intake manifold air pressure and
prevents over boosting at high engine speeds. When
the wastegate valve is closed, all of the exhaust gases
flow through the turbine wheel. As the intake mani-
fold pressure increases, the wastegate actuator opens
the valve, diverting some of the exhaust gases away
from the turbine wheel. This limits turbine shaft
speed and air output from the impeller.
The turbocharger is lubricated by engine oil that is
pressurized, cooled, and filtered. The oil is delivered
to the turbocharger by a supply line that is tapped
into the oil filter head. The oil travels into the bear-
ing housing, where it lubricates the shaft and bear-
ings (Fig. 4). A return pipe at the bottom of the
Fig. 1 Turbocharger Operation
1 - TURBINE SECTION
2 - EXHAUST GAS
3 - BEARING HOUSING
4 - COMPRESSOR SECTION
5 - INLET AIR
6 - COMPRESSED AIR TO ENGINE
7 - EXHAUST GAS
8 - EXHAUST GAS TO EXHAUST PIPE
Fig. 2 Turbocharger Wastegate Actuator
1 - TURBOCHARGER
2 - DIAPHRAGM
3 - WASTE GATE ACTUATOR
11a - 2 EXHAUST SYSTEM AND TURBOCHARGERRG
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(2) Fill the fluid reservoir to the proper level and
let the fluid settle for at least two (2) minutes.
(3) Start the engine and let run for a few seconds,
then turn the engine off.
(4) Add fluid if necessary. Repeat the above steps
until the fluid level remains constant after running
the engine.
(5) Raise the front wheels off the ground.
(6) Start the engine.
(7) Slowly turn the steering wheel right and left,
lightly contacting the wheel stops.
(8) Add fluid if necessary.
(9) Lower the vehicle, then turn the steering wheel
slowly from lock-to-lock.
(10) Stop the engine. Check the fluid level and
refill as required.
(11) If the fluid is extremely foamy, allow the vehi-
cle to stabilize a few minutes, then repeat the above
procedure.
REMOVAL
REMOVAL - PUMP (2.4L ENGINE)
(1) Remove the (-) negative battery cable from the
battery and isolate cable.
(2) Remove the cap from the power steering fluid
reservoir.
(3) Using a siphon pump, remove as much power
steering fluid as possible from the power steering
fluid reservoir.
(4) Raise the vehicle on jack stands or centered on
a frame contact type hoist. See Hoisting in Lubrica-
tion and Maintenance.
(5) Disconnect the oxygen sensor wiring harness
from the vehicle wiring harness at the rear engine
mount bracket.
NOTE: The exhaust system needs to be removed
from the engine to allow for an area to remove the
power steering pump from the vehicle.
(6) Remove the four bolts and flag nuts securing
the catalytic converter from the exhaust manifold
(Fig. 3).(7) Disconnect all the exhaust system isolators/
hangers from the brackets on the exhaust system (2
at the mufflers and 1 at the resonator) (Fig. 4).
(8) Remove the exhaust system by moving it as far
rearward, then lowering the front below the cross-
member and out of the vehicle.
(9) Remove the power steering fluid supply hose
from the fitting on the power steering pump. Drain
off excess power steering fluid from hose.
(10) Move the heat sleeve on the power steering
return hose to expose the hose connection at the
pump (Fig. 5). Remove the hose from the power
steering Pump. Allow the remaining power steering
fluid to drain from the power steering pump and res-
ervoir through the removed return hose.
(11) Remove the power steering fluid pressure line
from the power steering pump (Fig. 6). Drain excess
power steering fluid from tube.
(12) Remove the fasteners, then the accessory
drive splash shield.
Fig. 3 Catalytic Converter to Exhaust Manifold
1 - CATALYTIC CONVERTER
2 - BOLT
3 - GASKET
4 - FLAG NUT
19 - 38 PUMPRS
PUMP (Continued)
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Install an engine tachometer, raise vehicle on hoist
which allows front wheels to turn, and position
tachometer so it can be read.
Attach 300 psi gauge (C-3293SP) to port(s)
required for test(s) being conducted. Use adapter set
L-4559 to adapt gauge(s) to transaxle.
Test port locations are shown in (Fig. 4).
TEST ONE-SELECTOR IN LOW (1st GEAR)
(1) Attach pressure gauge to the low/reverse clutch
tap.
(2) Move selector lever to the (L) position.
(3) Allow vehicle wheels to turn and increase
throttle opening to achieve an indicated vehicle speed
to 20 mph.
(4) Low/reverse clutch pressure should read 115 to
145 psi.
(5) This test checks pump output, pressure regula-
tion and condition of the low/reverse clutch hydraulic
circuit and shift schedule.
TEST TWO-SELECTOR IN DRIVE (2nd GEAR)
NOTE: This test checks the underdrive clutch
hydraulic circuit as well as the shift schedule.
(1) Attach gauge to the underdrive clutch tap.
(2) Move selector lever to the 3 position.
(3) Allow vehicle wheels to turn and increase
throttle opening to achieve an indicated vehicle speed
of 30 mph.
(4) In second gear the underdrive clutch pressure
should read 110 to 145 psi.
TEST TWO A±SELECTOR IN OD (4th Gear)
NOTE: This test checks the underdrive clutch
hydraulic circuit as well as the shift schedule.
(1) Attach gauge to the underdrive clutch tap.
(2) Move selector lever to the (OD) position.
(3) Allow wheels to rotate freely and increase
throttle opening to achieve an indicated speed of 40
mph.
(4) Underdrive clutch pressure should read below
5 psi. If not, then either the solenoid assembly or
TCM is at fault.
TEST THREE-OVERDRIVE CLUTCH CHECK (3rd and
2nd Gear)
(1) Attach gauge to the overdrive clutch tap.
(2) Move selector lever to the (OD) position.
(3) Allow vehicle wheels to turn and increase
throttle opening to achieve an indicated vehicle speed
of 20 mph. Vehicle should be in 3rd gear.
(4) Overdrive clutch pressure should read 74 to 95
psi.
(5) Move selector lever to the (3) position and
increase indicated vehicle speed to 30 mph.
(6) The vehicle should be in second gear and over-
drive clutch pressure should be less than 5 psi.
(7) This test checks the overdrive clutch hydraulic
circuit as well as the shift schedule.
TEST FOUR-SELECTOR IN OVERDRIVE (4th Gear)
(1) Attach gauge to the 2/4 clutch tap.
(2) Move selector lever to the (OD) position.
(3) Allow vehicle front wheels to turn and increase
throttle opening to achieve an indicated vehicle speed
of 30 mph. Vehicle should be in 4th gear.
(4) The 2/4 clutch pressure should read 75 to 95
psi.
(5) This test checks the 2/4 clutch hydraulic cir-
cuit.
TEST FIVE-SELECTOR IN OVERDRIVE (4th Gear-CC
on)
(1) Attach gauge to the torque converter clutch off
pressure tap.
(2) Move selector lever to the (OD) position.
(3) Allow vehicle wheels to turn and increase
throttle opening to achieve an indicated vehicle speed
of 50 mph. Vehicle should be in 4th gear, CC on.
CAUTION: Both wheels must turn at the same
speed.
(4) Torque converter clutch off pressure should be
less than 5 psi.
(5) This test checks the torque converter clutch
hydraulic circuit.
Fig. 4 Pressure Taps
1 - OVERDRIVE CLUTCH
2 - TORQUE CONVERTER OFF
3 - LOW/REVERSE CLUTCH
4 - 2/4 CLUTCH
5 - REVERSE CLUTCH
6 - UNDERDRIVE CLUTCH
21 - 166 41TE AUTOMATIC TRANSAXLERS
41TE AUTOMATIC TRANSAXLE (Continued)
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(a) Align the valve notch in the wheel cover with
the valve stem on the wheel.
(b) At the same time, align the two holes in the
wheel cover having the retaining tabs with the two
installed wheel nuts (Fig. 15).
(c) Press in on center of wheel cover until wheel
cover retaining tabs push past and engage rear of
previously installed wheel mounting nuts (Fig. 15).
This will hold the wheel cover in place.
(4) Install andlightly tightenthe three remain-
ing wheel mounting nuts, securing the wheel cover in
place (Fig. 12).
(5) Progressively tighten all five wheel mounting
nuts in the proper sequence (Fig. 16). Tighten wheel
nuts to a torque of 135 N´m (100 ft. lbs.).
(6) Lower the vehicle.TIRE PRESSURE MONITORING
(TPM)
DESCRIPTION
Some versions of this vehicle are equipped with a
Tire Pressure Monitoring (TPM) system. It monitors
air pressure in the four road tires (excludes spare).
Pressure in the spare tire is not monitored.
There is a sensor (transmitter) in each of the vehi-
cle's four road wheels. The system alerts the driver
when tire pressure falls outside predetermined
thresholds (pressure too low or too high). A message
is then displayed on the Electronic Vehicle Informa-
tion Center (EVIC) located in the overhead console.
For further information, refer to the Owners Man-
ual or the appropriate diagnostic information.
OPERATION
The Tire Pressure Monitoring (TPM) system uses
radio and sensor technology to monitor tire air pres-
sure levels. Sensors, mounted to each road wheel as
part of the valve stem, transmit tire pressure read-
ings to a receiver located in the overhead console.
These transmissions occur once every minute at
speeds over 20 mph (32 km/h). The Tire Pressure
Monitoring system remains active even if no tire
pressure related message is displayed in the EVIC.
If any road tire pressure has exceeded the low or
high pressure threshold (refer to chart below), the
TPM system will display a message in the EVIC and
sound a chime. This message will be displayed for
the rest of the ignition cycle, or until either the Low/
High Tire pressure condition has been corrected. If
the C/T, MENU, STEP or RESET button is pressed,
the message is replaced by the new message
requested; however, if the Low/High Tire condition
has not been corrected, the Low/High Tire pressure
message will again be displayed.
If a road tire is replaced by the spare, the TPM
system will detect the swap and the message9SPARE
TIRE IN USE? Y/N9(along with a chime) will be dis-
played.
For further information, refer to the Owners Man-
ual or the Appropriate Diagnostic Information.
TPM THRESHOLD PRESSURES
High Pressure ON Threshold 48 PSI (331 kPa)
High Pressure OFF Threshold 43 PSI (296 kPa)
Placard Pressure (Cold) 36 PSI (248 kPa)
Low Pressure OFF Threshold 33 PSI (228 kPa)
Low Pressure ON Threshold 28 PSI (193 kPa)
Fig. 15 WHEEL COVER INSTALLATION OVER TWO
NUTS
1 - RETAINING TABS
2 - VALVE STEM
3 - BOLT-ON WHEEL COVER
Fig. 16 NUT TIGHTENING SEQUENCE
RSTIRES/WHEELS22-9
TIRES/WHEELS (Continued)
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The compressor clutch plate and pulley unit, or the
clutch coil are available for separate service replace-
ment. The clutch coil zener diode is integral to the
clutch coil pigtail wire and connector and, if faulty or
damaged, the clutch electromagnetic coil unit must
be replaced.
OPERATION
The compressor clutch components provide the
means to engage and disengage the compressor from
the engine serpentine accessory drive belt. When the
clutch coil is energized, it magnetically draws the
clutch plate into contact with the clutch pulley and
drives the compressor shaft. When the coil is not
energized, the pulley freewheels on the clutch hub
bearing, which is part of the pulley.
A zener diode is connected in parallel with the
clutch electromagnetic coil. This diode controls the
dissipation of voltage induced into the coil windings
by the collapsing of the electromagnetic fields that
occurs when the compressor clutch is disengaged.
The zener diode dissipates this induced voltage by
regulating a current path to ground. This arrange-
ment serves to protect other circuits and components
from potentially damaging voltage spikes in the vehi-
cle electrical system that might occur if the voltage
induced in the clutch coil windings could not be dis-
sipated.
The compressor clutch engagement is controlled by
several components: the heater-A/C controls in the
passenger compartment, the A/C pressure transducer
on the liquid line, the evaporator temperature sensor
on the expansion valve, the Powertrain Control Mod-ule (PCM) in the engine compartment, and the com-
pressor clutch relay in the Intelligent Power Module
(IPM). The PCM may delay compressor clutch
engagement for up to thirty seconds. (Refer to 8 -
ELECTRICAL/ELECTRONIC CONTROL MOD-
ULES/POWERTRAIN CONTROL MODULE -
DESCRIPTION - PCM OPERATION).
STANDARD PROCEDURE
STANDARD PROCEDURE - COMPRESSOR
CLUTCH AIR GAP
If a new clutch plate and/or clutch pulley are being
used, the air gap between the clutch plate and clutch
pulley must be checked using the following proce-
dure:
(1) Using feeler gauges, measure the air gap
between the clutch plate and the clutch pulley fric-
tion surfaces.
(2) If the air gap is not between 0.5 and 0.9 mm
(0.020 and 0.035 in.), add or subtract shims until the
desired air gap is obtained.
NOTE: The shims may compress after tightening
the compressor shaft bolt. Check the air gap in four
or more places on the clutch plate to verify that the
air gap is still correct. Spin the clutch pulley before
making the final air gap check.
STANDARD PROCEDURE - COMPRESSOR
CLUTCH BREAK-IN
After a new compressor clutch has been installed,
check that the compressor clutch coil is performing to
specifications. (Refer to 24 - HEATING & AIR CON-
DITIONING/CONTROLS - FRONT/COMPRESSOR
CLUTCH COIL - DIAGNOSIS AND TESTING). If
the clutch coil is performing to specifications, per-
form the compressor clutch break-in procedure. This
procedure (burnishing) will seat the opposing friction
surfaces and provide a higher compressor clutch
torque capability.
(1) Set the heater-A/C controls to the A/C mode,
with the blower switch in the highest speed position.
(2) Start the engine and hold the engine speed at
1500 to 2000 rpm.
(3) Cycle the compressor clutch On and Off about
twenty times (five seconds On, then five seconds Off).
REMOVAL
The refrigerant system can remain fully charged
during compressor clutch, pulley, or coil replacement.
Although the compressor assembly must be removed
from its mounting, the compressor clutch can be ser-
vice with the compressor in the vehicle.
Fig. 11 Compressor Clutch - Typical
1 - CLUTCH PLATE
2 - SHAFT KEY (SOME MODELS)
3 - PULLEY AND BEARING
4 - CLUTCH COIL
5 - CLUTCH SHIMS
6 - SNAP RING
7 - SNAP RING
RSCONTROLS - FRONT24-17
COMPRESSOR CLUTCH (Continued)
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