2001 DODGE TOWN AND COUNTRY sensor

FUEL PUMP RELAY
DESCRIPTION
The fuel pump relay is located in the PDC. The
inside top of the PDC cover has a label showing relay
and fuse location.
OPERATION
The fuel pump relay supplies battery voltage to the
fuel pump. A buss bar in the Power Distribution Cen-
ter (PDC) supplies voltage to the solenoid side and
contact side of the relay. The fuel pump relay power
circuit contains a fuse between the buss bar in the
PDC and the relay. The fuse also protects the power
circuit for the Automatic Shutdown (ASD) relay. The
fuse is located in the PDC. Refer to the Wiring Dia-
grams for circuit information.
The PCM controls the fuel pump relay by switch-
ing the ground path for the solenoid side of the relay
on and off. The PCM turns the ground path off when
the ignition switch is in the Off position. When the
ignition switch is in the On position, the PCM ener-
gizes the fuel pump. If the crankshaft position sensor
does not detect engine rotation, the PCM de-ener-
gizes the relay after approximately one second.
IDLE AIR CONTROL MOTOR
DESCRIPTION
The idle air control motor is mounted on the throt-
tle body. The PCM operates the idle air control motor
(Fig. 11) or (Fig. 12).
OPERATION
The PCM adjusts engine idle speed through the
idle air control motor to compensate for engine load,
coolant temperature or barometric pressure changes.
The throttle body has an air bypass passage that
provides air for the engine during closed throttle idle.
The idle air control motor pintle protrudes into the
air bypass passage and regulates air flow through it.
The PCM adjusts engine idle speed by moving the
IAC motor pintle in and out of the bypass passage.
The adjustments are based on inputs the PCM
receives. The inputs are from the throttle position
sensor, crankshaft position sensor, coolant tempera-
ture sensor, MAP sensor, vehicle speed sensor and
various switch operations (brake, park/neutral, air
conditioning).
When engine rpm is above idle speed, the IAC is
used for the following functions:
²Off-idle dashpot
²Deceleration air flow control
²A/C compressor load control (also opens the pas-
sage slightly before the compressor is engaged sothat the engine rpm does not dip down when the
compressor engages)
Target Idle
Target idle is determined by the following inputs:
²Gear position
²ECT Sensor
²Battery voltage
²Ambient/Battery Temperature Sensor
²VSS
Fig. 11 TPS/IAC 2.4L
1 - IAC MOTOR
2 - TP SENSOR
3 - IAT SENSOR
Fig. 12 TPS/IAC 3.3/3.8L
1 - IDLE AIR CONTROL VALVE
2 - TP SENSOR
RSFUEL INJECTION14-27
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²TPS
²MAP Sensor
REMOVAL
When servicing throttle body components, always
reassemble components with new O-rings and seals
where applicable. Never use lubricants on O-rings or
seals, damage may result. If assembly of component
is difficult, use water to aid assembly. Use care when
removing hoses to prevent damage to hose or hose
nipple.
(1) Disconnect negative cable from battery.
(2) Remove electrical connector from idle air con-
trol motor.
(3) Remove idle air control motor mounting screws.
(4) Remove motor from throttle body. Ensure the
O-rings is removed with the motor.
INSTALLATION
When servicing throttle body components, always
reassemble components with new O-rings and seals
where applicable. Never use lubricants on O-rings or
seals, damage may result. If assembly of component
is difficult,a light coat of engine oil may be
applied to the O-RINGS ONLY (Fig. 13)to aid
assembly. Use care when removing hoses to prevent
damage to hose or hose nipple.
(1) The new idle air control motor has a new
O-ring installed on it. For 2.4L only, if pintle mea-
sures more than 1 inch (25 mm) it must be retracted.
Use the DRB Idle Air Control Motor Open/Close Test
to retract the pintle (battery must be connected.)
(2) Carefully place idle air control motor into
throttle body.
(3) Install mounting screw(s). Tighten screws to 2
N´m (17 in. lbs.) torque.
(4) Connect electrical connector to idle air control
motor.
(5) Connect negative cable to battery.
INLET AIR TEMPERATURE
SENSOR
DESCRIPTION
The IAT Sensor is a Negative Temperature Coeffi-
cient (NTC) Sensor that provides information to the
PCM regarding the temperature of the air entering
the intake manifold (Fig. 14).
OPERATION
Inlet/Intake Air Temperature
The inlet air temperature sensor replaces the
intake air temperature sensor and the battery tem-
perature sensor. The PCM uses the information from
the inlet air temperature sensor to determine values
to use as an intake air temperature sensor and a bat-
tery temperature sensor.
The Intake Air Temperature (IAT) sensor value is
used by the PCM to determine air density.
The PCM uses this information to calculate:
²Injector pulse width
²Adjustment of ignition timing (to prevent spark
knock at high intake air temperatures)
Battery Temperature
The inlet air temperature sensor replaces the
intake air temperature sensor and the battery tem-
perature sensor. The PCM uses the information from
the inlet air temperature sensor to determine values
for the PCM to use as an intake air temperature sen-
sor and a battery temperature sensor.
The battery temperature information along with
data from monitored line voltage (B+), is used by the
Fig. 13 O-RINGS
1 - O-rings
Fig. 14 3.3/3.8L IAT SENSOR
1 - INLET AIR TEMPERATURE SENSOR
14 - 28 FUEL INJECTIONRS
IDLE AIR CONTROL MOTOR (Continued)
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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)
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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)
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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)
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input from the upstream sensor, the PCM calculates
catalytic convertor efficiency.
REMOVAL - UPSTREAM 1/1 - 2.4L
(1) Disconnect the negative battery cable.
(2) Raise and support the vehicle.
(3) Disconnect the electrical connector (Fig. 18).
(4) Use a socket such as the Snap-OntYA8875 or
equivalent to remove the sensor
(5) When the sensor is removed, the threads must
be cleaned with an 18 mm X 1.5 + 6E tap. If using
the original sensor, coat the threads with Loctite
771±64 anti-seize compound or equivalent.
REMOVAL - UPSTREAM 1/1 - 3.3/3.8L
(1) Remove battery, refer to the Battery section for
more information.
(2) Remove the battery tray, refer to the Battery
section for more information.
(3) Disconnect the speed control vacuum harness
from servo.
(4) Disconnect the electrical connector from servo.
(5) Remove the speed control servo and bracket
and reposition.
(6) Use a socket such as the Snap-OntYA8875 or
equivalent to remove the sensor (Fig. 20).
(7) When the sensor is removed, the threads must
be cleaned with an 18 mm X 1.5 + 6E tap. If using
the original sensor, coat the threads with Loctite
771±64 anti-seize compound or equivalent.
REMOVAL - DOWNSTREAM 1/2 - 2.4/3.3/3.8L
(1) Disconnect the negative battery cable.
(2) Raise and support the vehicle.
(3) Disconnect the electrical connector (Fig. 21).
(4) Use a socket such as the Snap-OntYA8875 or
equivalent to remove the sensor (Fig. 19).
(5) When the sensor is removed, the threads must
be cleaned with an 18 mm X 1.5 + 6E tap. If using
Fig. 20 O2 SENSOR 1/1
Fig. 21 Downstream Oxygen Sensor (1/2)
1 - OXYGEN SENSOR CONNECTOR
2 - CATALYTIC CONVERTER
3 - DOWNSTREAM OXYGEN SENSOR
4 - ENGINE HARNESS CONNECTOR
Fig. 22 DOWNSTREAM 2/1 O2 SENSOR
14 - 32 FUEL INJECTIONRS
O2 SENSOR (Continued)
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the original sensor, coat the threads with Loctite
771±64 anti-seize compound or equivalent.
INSTALLATION - UPSTREAM 1/1 - 2.4L
The engines uses two heated oxygen sensors.
(1) After removing the sensor, the exhaust mani-
fold threads must be cleaned with an 18 mm X 1.5 +
6E tap. If reusing the original sensor, coat the sensor
threads with an anti-seize compound such as Loctite
771- 64 or equivalent. New sensors have compound
on the threads and do not require an additional coat-
ing.
(2) Install sensor and tighten to 27 N´m (20 ft.
lbs.) (Fig. 18).
(3) Connect the electrical connector for the O2 sen-
sor and install onto bracket.
(4) Lower vehicle.
(5) Connect the negative battery cable.
INSTALLATION - UPSTREAM 1/1 - 3.3/3.8L
The engines uses two heated oxygen sensors.
(1) After removing the sensor, the exhaust mani-
fold threads must be cleaned with an 18 mm X 1.5 +
6E tap. If reusing the original sensor, coat the sensor
threads with an anti-seize compound such as Loctite
771- 64 or equivalent. New sensors have compound
on the threads and do not require an additional coat-
ing.
(2) Install sensor and tighten to 27 N´m (20 ft.
lbs.).
(3) Connect the electrical connector for the O2 sen-
sor and install onto bracket.
(4) Connect the electrical connector for the speed
control servo.
(5) Install the speed control servo and bracket
refer to the Speed Control Servo for more informa-
tion.
(6) Connect the speed control vacuum harness to
servo.
(7) Install the battery tray, refer to the Battery
section for more information.
(8) Install battery, refer to the Battery section for
more information.
INSTALLATION DOWNSTREAM 2/1 -
2.4/3.3/3.8L
The O2S are located on the side of the catalytic
converter.
Threads of new oxygen sensors are factory coated
with anti-seize compound to aid in removal.DO
NOT add any additional anti-seize compound to
the threads of a new oxygen sensor.
(1) Install sensor and tighten to 27 N´m (20 ft.
lbs.).
(2) Connect the electrical connector.
(3) Lower vehicle.(4) Install the negative battery cable.
THROTTLE BODY
DESCRIPTION
The throttle body is located on the intake manifold
(Fig. 23) or (Fig. 24). Fuel does not enter the intake
manifold through the throttle body. Fuel is sprayed
into the manifold by the fuel injectors.
Fig. 23 IAC MOTOR 2.4L
1 - IAC MOTOR
2 - TP SENSOR
3 - IAT SENSOR
Fig. 24 IAC MOTOR LOCATION
1 - IDLE AIR CONTROL VALVE
2 - TP SENSOR
RSFUEL INJECTION14-33
O2 SENSOR (Continued)
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OPERATION
Filtered air from the air cleaner enters the intake
manifold through the throttle body. The throttle body
contains an air control passage controlled by an Idle
Air Control (IAC) motor. The air control passage is
used to supply air for idle conditions. A throttle valve
(plate) is used to supply air for above idle conditions.
Certain sensors are attached to the throttle body.
The accelerator pedal cable, speed control cable and
transmission control cable (when equipped) are con-
nected to the throttle body linkage arm.
A (factory adjusted) set screw is used to mechani-
cally limit the position of the throttle body throttle
plate.Never attempt to adjust the engine idle
speed using this screw.All idle speed functions are
controlled by the PCM.
REMOVAL
(1) Disconnect negative cable from battery cable.
(2) Remove air inlet to throttle body hose clamp.
(3) Remove throttle and the speed control (if
equipped) cables from lever and bracket.
(4) Disconnect electrical connectors from the idle
air control motor and throttle position sensor (TPS)
(Fig. 23) or (Fig. 24).
(5) Remove throttle body to intake manifold
attaching bolts.
(6) Remove throttle body and gasket.
INSTALLATION
(1) Install a new gasket.
(2) Install throttle body.
(3) Tighten throttle body mounting bolts. The 2.4L
to 28.2 N´m (250650 in. lbs.) torque, The 3.3/3.8L to
11.6 N´m (105620 in. lbs.) torque.
(4) Connect electrical connectors to the idle air
control motor and throttle position sensor (TPS) (Fig.
23) or (Fig. 24).
(5) Install air inlet to throttle body hose clamp and
tighten.
(6) Connect negative cable to battery cable.
THROTTLE CONTROL CABLE
REMOVAL
(1) Working from the engine compartment, hold
the throttle body throttle lever in the wide open posi-
tion.
(2) Remove the throttle cable from the throttle
body cam.
(3) From inside the vehicle, hold up the pedal and
remove the cable retainer and throttle cable from the
upper end of the pedal shaft.
(4) Remove retainer clip from throttle cable and
grommet at dash panel.(5) From the engine compartment, pull the throttle
cable out of the dash panel grommet. The grommet
should remain in the dash panel.
(6) Remove the throttle cable from throttle bracket
by carefully compressing both retaining ears simulta-
neously. Then gently pull the throttle cable from
throttle bracket.
INSTALLATION
(1) From the engine compartment, push the hous-
ing end fitting into the dash panel grommet.
(2) Install the cable housing (throttle body end)
into the cable mounting bracket on the engine.
(3) From inside the vehicle, hold up the pedal and
install throttle cable and cable retainer in the upper
end of the pedal shaft.
(4) At the dash panel, install the cable retainer
clip between the end of the throttle cable fitting and
grommet
(5) From the engine compartment, rotate the
throttle lever wide open and install the throttle
cable.
THROTTLE POSITION SENSOR
DESCRIPTION
The throttle position sensor mounts to the side of
the throttle body (Fig. 25) or (Fig. 26).The sensor
connects to the throttle blade shaft. The TPS is a
variable resistor that provides the Powertrain Con-
trol Module (PCM) with an input signal (voltage).
Fig. 25 Throttle Position SensorÐ2.4L Engine
1 - IAC MOTOR
2 - TP SENSOR
3 - IAT SENSOR
14 - 34 FUEL INJECTIONRS
THROTTLE BODY (Continued)
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