PCM to vary the battery charging rate. System volt-
age will be higher at colder temperatures and is
gradually reduced at warmer temperatures.
The battery temperature information is also used
for OBD II diagnostics. Certain faults and OBD II
monitors are either enabled or disabled depending
upon the battery temperature sensor input (example:
disable purge, enable LDP). Most OBD II monitors
are disabled below 20ÉF.
MAP SENSOR
DESCRIPTION
The MAP sensor (Fig. 15) or (Fig. 16) mounts to
the intake manifold. The sensor is connects electri-
cally to the PCM.
OPERATION
The MAP serves as a PCM input, using a silicon
based sensing unit, to provide data on the manifold
vacuum that draws the air/fuel mixture into the com-
bustion chamber. The PCM requires this information
to determine injector pulse width and spark advance.
When MAP equals Barometric pressure, the pulse
width will be at maximum.
Also like the cam and crank sensors, a 5 volt ref-
erence is supplied from the PCM and returns a volt-
age signal to the PCM that reflects manifold
pressure. The zero pressure reading is 0.5V and full
scale is 4.5V. For a pressure swing of0Ð15psithe
voltage changes 4.0V. The sensor is supplied a regu-
lated 4.8 to 5.1 volts to operate the sensor. Like the
cam and crank sensors ground is provided through
the sensor return circuit.
The MAP sensor input is the number one contributor
to pulse width. The most important function of the MAP
sensor is to determine barometric pressure. The PCM
needs to know if the vehicle is at sea level or is it in
Denver at 5000 feet above sea level, because the air
density changes with altitude. It will also help to correct
for varying weather conditions. If a hurricane was com-
ing through the pressure would be very, very low or
there could be a real fair weather, high pressure area.
This is important because as air pressure changes the
barometric pressure changes. Barometric pressure and
altitude have a direct inverse correlation, as altitude
goes up barometric goes down. The first thing that hap-
pens as the key is rolled on, before reaching the crank
position, the PCM powers up, comes around and looks
at the MAP voltage, and based upon the voltage it sees,
it knows the current barometric pressure relative to
altitude. Once the engine starts, the PCM looks at the
voltage again, continuously every 12 milliseconds, and
compares the current voltage to what it was at key on.
The difference between current and what it was at key
on is manifold vacuum.
During key On (engine not running) the sensor
reads (updates) barometric pressure. A normal range
can be obtained by monitoring known good sensor in
you work area.
As the altitude increases the air becomes thinner
(less oxygen). If a vehicle is started and driven to a
very different altitude than where it was at key On
the barometric pressure needs to be updated. Any
time the PCM sees Wide Open throttle, based upon
TPS angle and RPM it will update barometric pres-
sure in the MAP memory cell. With periodic updates,
the PCM can make its calculations more effectively.
Fig. 15 MAP SENSOR - 2.4L
1 - MAP SENSOR
Fig. 16 MAP SENSOR - 3.3/3.8L
1 - MAP SENSOR
RSFUEL INJECTION14-29
INLET AIR TEMPERATURE SENSOR (Continued)
The PCM uses the MAP sensor to aid in calculat-
ing the following:
²Barometric pressure
²Engine load
²Manifold pressure
²Injector pulse-width
²Spark-advance programs
²Shift-point strategies (F4AC1 transmissions
only, via the PCI bus)
²Idle speed
²Decel fuel shutoff
The PCM recognizes a decrease in manifold pressure
by monitoring a decrease in voltage from the reading
stored in the barometric pressure memory cell. The
MAP sensor is a linear sensor; as pressure changes,
voltage changes proportionately. The range of voltage
output from the sensor is usually between 4.6 volts at
sea level to as low as 0.3 volts at 26 in. of Hg. Baromet-
ric pressure is the pressure exerted by the atmosphere
upon an object. At sea level on a standard day, no
storm, barometric pressure is 29.92 in Hg. For every
100 feet of altitude barometric pressure drops .10 in.
Hg. If a storm goes through it can either add, high pres-
sure, or decrease, low pressure, from what should be
present for that altitude. You should make a habit of
knowing what the average pressure and corresponding
barometric pressure is for your area.
REMOVAL - 2.4L
(1) Disconnect the negative battery cable.
(2) Disconnect electrical connector and vacuum
hose from MAP sensor (Fig. 15).
(3) Remove two screws holding sensor to the
intake manifold.
REMOVAL - 3.3/3.8L
(1) Disconnect the negative battery cable.
(2)
Remove vacuum hose and mounting screws from
manifold absolute pressure (MAP) sensor (Fig. 16).
(3) Disconnect electrical connector from sensor.
Remove sensor.
INSTALLATION - 2.4L
(1) Install sensor.
(2) Install two screws and tighten.
(3) Connect the electrical connector and vacuum
hose to the MAP sensor (Fig. 15).
(4) Connect the negative battery cable.
INSTALLATION - 3.3/3.8L
(1) Install sensor (Fig. 16).
(2) Install screws and tighten toPLASTIC MAN-
IFOLD 1.7 N´m (15 in. lbs.) ALUMINUM MANI-
FOLD 3.3 N´m (30 in. lbs.).
(3) Connect the electrical connector to the sensor.
Install vacuum hose.(4) Connect the negative battery cable.
O2 SENSOR
DESCRIPTION
The upstream oxygen sensor threads into the out-
let flange of the exhaust manifold (Fig. 17) or (Fig.
18).
Fig. 17 O2 SENSOR UPSTREAM 1/1 - 2.4L
1 - 1/1 02 SENSOR
Fig. 18 O2 SENSOR UPSTREAM 1/1 - 3.3/3.8L
1 - 1/1 02 SENSOR
14 - 30 FUEL INJECTIONRS
MAP SENSOR (Continued)
The downstream heated oxygen sensor threads into
the outlet pipe at the rear of the catalytic convertor
(Fig. 19).
OPERATION
Separate controlled ground circuits are run
through the PCM for the upstream O2 sensors.
As vehicles accumulate mileage, the catalytic con-
vertor deteriorates. The deterioration results in a
less efficient catalyst. To monitor catalytic convertor
deterioration, the fuel injection system uses two
heated oxygen sensors. One sensor upstream of the
catalytic convertor, one downstream of the convertor.
The PCM compares the reading from the sensors to
calculate the catalytic convertor oxygen storage
capacity and converter efficiency. Also, the PCM uses
the upstream heated oxygen sensor input when
adjusting injector pulse width.
When the catalytic converter efficiency drops below
emission standards, the PCM stores a diagnostic
trouble code and illuminates the malfunction indica-
tor lamp (MIL).
The O2S produce voltages from 0 to 1 volt, depend-
ing upon the oxygen content of the exhaust gas in
the exhaust manifold. When a large amount of oxy-
gen is present (caused by a lean air/fuel mixture), the
sensors produces a low voltage. When there is a
lesser amount present (rich air/fuel mixture) it pro-
duces a higher voltage. By monitoring the oxygen
content and converting it to electrical voltage, the
sensors act as a rich-lean switch.The oxygen sensors are equipped with a heating
element that keeps the sensors at proper operating
temperature during all operating modes. Maintaining
correct sensor temperature at all times allows the
system to enter into closed loop operation sooner.
Also, it allows the system to remain in closed loop
operation during periods of extended idle.
In Closed Loop operation the PCM monitors the
O2S input (along with other inputs) and adjusts the
injector pulse width accordingly. During Open Loop
operation the PCM ignores the O2 sensor input. The
PCM adjusts injector pulse width based on prepro-
grammed (fixed) values and inputs from other sen-
sors.
The Automatic Shutdown (ASD) relay supplies bat-
tery voltage to both the upstream and downstream
heated oxygen sensors. The oxygen sensors are
equipped with a heating element. The heating ele-
ments reduce the time required for the sensors to
reach operating temperature.
UPSTREAM OXYGEN SENSOR
The input from the upstream heated oxygen sensor
tells the PCM the oxygen content of the exhaust gas.
Based on this input, the PCM fine tunes the air-fuel
ratio by adjusting injector pulse width.
The sensor input switches from 0 to 1 volt, depend-
ing upon the oxygen content of the exhaust gas in
the exhaust manifold. When a large amount of oxy-
gen is present (caused by a lean air-fuel mixture), the
sensor produces voltage as low as 0.1 volt. When
there is a lesser amount of oxygen present (rich air-
fuel mixture) the sensor produces a voltage as high
as 1.0 volt. By monitoring the oxygen content and
converting it to electrical voltage, the sensor acts as
a rich-lean switch.
The heating element in the sensor provides heat to
the sensor ceramic element. Heating the sensor
allows the system to enter into closed loop operation
sooner. Also, it allows the system to remain in closed
loop operation during periods of extended idle.
In Closed Loop, the PCM adjusts injector pulse
width based on the upstream heated oxygen sensor
input along with other inputs. In Open Loop, the
PCM adjusts injector pulse width based on prepro-
grammed (fixed) values and inputs from other sen-
sors.
DOWNSTREAM OXYGEN SENSOR
The downstream heated oxygen sensor input is
used to detect catalytic convertor deterioration. As
the convertor deteriorates, the input from the down-
stream sensor begins to match the upstream sensor
input except for a slight time delay. By comparing
the downstream heated oxygen sensor input to the
Fig. 19 O2 SENSOR DOWNSTREAM 1/2 - 2.4/3.3/
3.8L
1 - 1/2 02S
2 - 1/1 02S
RSFUEL INJECTION14-31
O2 SENSOR (Continued)
OPERATION
The signal represents throttle blade position. As
the position of the throttle blade changes, the resis-
tance of the TPS changes.
The PCM supplies approximately 5 volts to the
TPS. The TPS output voltage (input signal to the
powertrain control module) represents throttle blade
position. The TPS output voltage to the PCM varies
from approximately 0.6 volt at minimum throttle
opening (idle) to a maximum of 4.5 volts at wide open
throttle.
Along with inputs from other sensors, the PCM
uses the TPS input to determine current engine oper-
ating conditions. The PCM also adjusts fuel injectorpulse width and ignition timing based on these
inputs.
REMOVAL
(1) Disconnect the negative battery cable.
(2) Remove the electrical connector from the Inlet
Air Temperature sensor.
(3) Remove the air cleaner box lid. Remove hose
from throttle body.
(4) Disconnect the electrical connector at TPS.
(5) Disconnect the electrical connector at IAC.
(6) Remove the throttle and speed control cables
from throttle body.
(7) Remove 3 mounting bolts from throttle body.
(8) Remove throttle body.
(9) Disconnect the purge vacuum line from the
throttle body.
(10) Remove TPS from throttle body.
INSTALLATION
(1) Install TPS to throttle body.
(2) Disconnect the purge vacuum line from the
throttle body.
(3) Install throttle body.
(4) Install 3 mounting bolts from throttle body.
Tighten bolts.
(5) Install the throttle and speed control cables to
throttle body.
(6) Connect the electrical connector at TPS.
(7) Connect the electrical connector at IAC.
(8) Install the air cleaner box lid. Install hose to
throttle body.
(9) Install the electrical connector to the Inlet Air
Temperature sensor.
(10) Connect the negative battery cable.
Fig. 26 Throttle Position SensorÐ3.3/3.8L Engine
1 - IDLE AIR CONTROL VALVE
2 - TP SENSOR
RSFUEL INJECTION14-35
THROTTLE POSITION SENSOR (Continued)
CLEANING - TIRES
Before delivery of a vehicle, remove the protective
coating on the tires with white sidewalls or raised
white letters. To remove the protective coating, apply
warm water and let it soak for a few minutes. After-
wards, scrub the coating away with a soft bristle
brush. Steam cleaning may also be used to remove
the coating.
CAUTION: DO NOT use gasoline, mineral oil, oil-
based solvent or a wire brush for cleaning.
WHEELS
DESCRIPTION - WHEEL
Original equipment wheels are designed for proper
operation at all loads up to the specified maximum
vehicle capacity.
All models use either steel or aluminum drop-cen-
ter wheels. Every wheel has raised sections between
the rim flanges and rim drop well called safety
humps (Fig. 23). Initial inflation of the tires forces
the bead over these raised sections. In case of air
loss, the safety humps hold the tire in position on the
wheel until the vehicle can be brought to a safe stop.
Cast aluminum wheels require special balance
weights to fit on the flange of the rim (Fig. 24).
When wheel alignment is necessary on a vehicle
with cast aluminum wheels, special wheel clamps are
required to avoid damage to the wheel's finish.The wheel studs and nuts are designed for specific
wheel applications and must be replaced with equiv-
alent parts.
All aluminum wheels have wheel mounting (lug)
nuts with an enlarged nose. This enlarged nose is
necessary to ensure proper retention of the wheels.
DIAGNOSIS AND TESTING - WHEEL
INSPECTION
Inspect wheels for:
²Excessive runout
²Dents, cracks or irregular bends
²Damaged wheel stud (lug) holes
²Air Leaks
NOTE: Do not attempt to repair a wheel by hammer-
ing, heating or welding.
If a wheel is damaged, an original equipment
replacement wheel should be used. When obtaining
replacement wheels, they should be equivalent in
load carrying capacity. The diameter, width, offset,
pilot hole and bolt circle of the wheel should be the
same as the original wheel.
WARNING: FAILURE TO USE EQUIVALENT
REPLACEMENT WHEELS MAY ADVERSELY
AFFECT THE SAFETY AND HANDLING OF THE
VEHICLE.
WARNING: REPLACEMENT WITH USED WHEELS IS
NOT RECOMMENDED. THE SERVICE HISTORY OF
THE WHEEL MAY HAVE INCLUDED SEVERE TREAT-
MENT OR VERY HIGH MILEAGE. THE RIM COULD
FAIL WITHOUT WARNING.
Fig. 23 Safety Rim
1 - TIRE
2 - WELL
3 - SAFETY HUMPS
4 - FLANGE
Fig. 24 Styled Aluminum Wheel Weight
1 - TIRE
2 - WHEEL
3 - STYLED WHEEL WEIGHT
RSTIRES/WHEELS22-13
TIRES (Continued)
(5) If desired, a thin film coat of poesy can be
applied to the back of the patch to cover mesh for
added strength.
PANEL PATCH INSTALLATION
(1) Make a paper or cardboard pattern the size
and shape of the cutout hole in the panel.
(2) Trim 3 mm (0.125 in.) from edges of pattern so
patch will have a gap between connecting surfaces.
(3) Using the pattern as a guide, cut the patch to
size.
(4) Cut scrap pieces of patch material into 50 mm
(2 in.) squares to use as patch supports to sustain
the patch in the cutout.
(5) Drill 4 mm (0.160 in.) holes 13 mm (0.5 in.) in
from edge of cutout hole (Fig. 8).
(6) Drill 3 mm (0.125 in.) holes in the support
squares 13 mm (0.5 in.) from the edge in the center
of one side.
(7) Scuff the backside of the body panel around the
cutout hole with a scuff pad or sandpaper.
(8) Mix enough epoxy to cover one side of all sup-
port squares.
(9) Apply epoxy to the support squares on the half
with the hole pre-drilled in it.
(10) Using number 8 sheet metal screws, secure
support squares to back side of body panel with
epoxy sandwiched between the panel and squares
(Fig. 10).
(11) Position patch in cutout against support
squares and adjust patch until the gap is equal along
all sides (Fig. 11).
(12) Drill 3 mm (0.125 in.) holes in the support
squares through the pre-drilled holes in the patch.
Fig. 9 FABRICATED PANEL
1 - STRUCTURAL ADHESIVE OR EPOXY RESIN
2 - FIBERGLASS CLOTH OR FIBERGLASS MESH TAPE
3 - WIDTH OF V-GROOVE
4 - WAXED PAPER
Fig. 10 Secure Support Squares To Body Panel
1 - SUPPORT SQUARES
2 - SCREWS
3 - DAMAGED BODY PANEL
Fig. 11 Position Patch In Cutout And Align
1 - CUTOUT
2 - SUPPORT SQUARES
Fig. 12 Apply Epoxy To Support Squares
1 - APPLICATOR
2 - SUPPORT SQUARES
3 - EPOXY
RSBODY23-7
BODY (Continued)
SPECIFICATIONS
SPECIFICATIONS - HEATER-A/C SYSTEM
ITEM DESCRIPTION NOTES
Vehicle RS - Caravan, Town & Country, Voyager
System R134a with expansion valve(s)
Compressor Nippondenso - 10S20 ND-8 PAG Oil
Freeze±up Control evaporator temperature sensor expansion valve mounted - input
to heater-A/C control module
Low PSI Control A/C pressure transducer liquid line mounted - input to
Powertrain Control Module (PCM)
- PCM opens compressor clutch
relay < 29.4 psi
High PSI Control pressure relief valve liquid line mounted - input to
PCM - PCM opens compressor
clutch relay > 450 psi
compressor mounted - opens >
495 psi
Control Head single zone, dual zone, and three zone
Manual Temperature Control (MTC) - or three
zone Automatic Temperature Control (ATC)PCI data bus messaging - ATC
uses three infrared temperature
sensors - two front/one rear
Mode Door electric actuator Control head driven
Blend Air Door electric actuator
Fresh/Recirc Door electric actuator
Blower Motor control head switch resistor and relay with MTC,
power module and relay with ATC
Cooling Fans pulse width modulated variable speed PCM control through solid state
fan relay
Clutch
Clutch Control PCM PCM control through compressor
clutch relay
Clutch Coil Draw 2.2 amps @ 12V60.5amps@ 70É F
Compressor Clutch Air Gap 0.0209- 0.0359
Diagnostics DRBIIITscan tool
RSHEATING & AIR CONDITIONING24-7
and is accessed for service by rolling down the glove
box from the instrument panel.
The power module heat sink will get hot when in
use. Do not touch the heat sink if the blower motor
has been running. The blower power module cannot
be adjusted or repaired and, if faulty or damaged, it
must be replaced.
OPERATION
The blower power module is connected to the vehi-
cle electrical system through a dedicated take out
and connector of the instrument panel wire harness.
A second connector receptacle receives the pigtail
wire connector from the blower motor. The blower
power module allows the microprocessor-based Auto-
matic Temperature Control (ATC) heater-A/C control
module to calculate and provide infinitely variable
blower motor speeds based upon either manual
blower switch input or the ATC programming using a
Pulse Width Modulated (PWM) circuit strategy. The
PWM voltage is applied to a comparator circuit
which compares the PWM signal voltage to the
blower motor feedback voltage. The resulting output
drives the power module circuitry, which adjusts the
voltage output received from the blower motor relay
to change or maintain the desired blower speed. The
blower power module is diagnosed using a DRBIIIt
scan tool. Refer to the appropriate diagnostic infor-
mation.
REMOVAL
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
(1) Disconnect and isolate the battery negative
cable.
(2) Open the glove box.
(3) Flex both sides of the glove box bin inward
near the top far enough for the rubber glove box stop
bumpers to clear the sides of the glove box opening,
then roll the glove box downward.
(4) Reach through the glove box opening to access
and disconnect the instrument panel wire harness
connector for the power module from the module con-
nector receptacle.
(5) Reach through the glove box opening to access
and disconnect the blower motor pigtail wire connec-
tor from the power module connector receptacle.
(6) Remove the two screws that secure the power
module to the evaporator housing.
(7) Remove the power module from the evaporator
housing.
INSTALLATION
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
(1) Position the power module into the evaporator
housing.
Fig. 23 Power Module
1 - POWER MODULE
2 - LOWER GLOVE BOX OPENING REINFORCEMENT
3 - EVAPORATOR HOUSING
RSCONTROLS - FRONT24-27
POWER MODULE (Continued)