DODGE RAM 2001 Service Repair Manual

(1) Install sensor to intake manifold. Tighten to
12±15 N´m (110±130 in. lbs.) torque.
(2) Install electrical connector.
(3) Install air cleaner.
INSTALLATION - 8.0L
The intake manifold air temperature sensor is
located in the side of the intake manifold near the
front of throttle body (Fig. 35).
(1) Install sensor to intake manifold. Tighten to
12±15 N´m (110±130 in. lbs.) torque.
(2) Install electrical connector.
MANIFOLD ABSOLUTE
PRESSURE SENSOR
DESCRIPTION - 3.9L/5.2L/5.9L/8.0L
On 3.9L/5.2L/5.9L engines, the MAP sensor is
mounted on the side of the engine throttle body. The
sensor is connected to the throttle body with a rubber
L-shaped fitting.
On the 8.0L 10±cylinder engine, the MAP sensor is
mounted into the right side of the intake manifold.
OPERATION - 3.9L/5.2L/5.9L/8.0L
The MAP sensor is used as an input to the Power-
train Control Module (PCM). It contains 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 manifold absolute pressure (MAP) equals
Barometric pressure, the pulse width will be at max-
imum.
A 5 volt reference is supplied from the PCM and
returns a voltage 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 of 0±15
psi, the voltage changes 4.0V. To operate the sensor,
it is supplied a regulated 4.8 to 5.1 volts. Ground is
provided through the low-noise, sensor return circuit
at the PCM.
The MAP sensor input is the number one contrib-
utor to fuel injector pulse width. The most important
function of the MAP sensor is to determine baromet-
ric pressure. The PCM needs to know if the vehicle is
at sea level or at a higher altitude, because the air
density changes with altitude. It will also help to cor-
rect for varying barometric pressure. Barometric
pressure and altitude have a direct inverse correla-
tion; as altitude goes up, barometric goes down. At
key-on, the PCM powers up and looks at MAP volt-
age, 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 voltageagain, continuously every 12 milliseconds, and com-
pares the current voltage to what it was at key-on.
The difference between current voltage 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 a known good sensor.
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 (WOT), based
upon Throttle Position Sensor (TPS) angle and RPM,
it will update barometric pressure in the MAP mem-
ory cell. With periodic updates, the PCM can make
its calculations more effectively.
The PCM uses the MAP sensor input to aid in cal-
culating the following:
²Manifold pressure
²Barometric pressure
²Engine load
²Injector pulse-width
²Spark-advance programs
²Shift-point strategies (certain automatic trans-
missions only)
²Idle speed
²Decel fuel shutoff
The MAP sensor signal is provided from a single
piezoresistive element located in the center of a dia-
phragm. The element and diaphragm are both made
of silicone. As manifold pressure changes, the dia-
phragm moves causing the element to deflect, which
stresses the silicone. When silicone is exposed to
stress, its resistance changes. As manifold vacuum
increases, the MAP sensor input voltage decreases
proportionally. The sensor also contains electronics
that condition the signal and provide temperature
compensation.
The PCM recognizes a decrease in manifold pres-
sure by monitoring a decrease in voltage from the
reading stored in the barometric pressure memory
cell. The MAP sensor is a linear sensor; meaning as
pressure changes, voltage changes proportionately.
The range of voltage output from the sensor is usu-
ally between 4.6 volts at sea level to as low as 0.3
volts at 26 in. of Hg. Barometric pressure is the pres-
sure exerted by the atmosphere upon an object. At
sea level on a standard day, no storm, barometric
pressure is approximately 29.92 in Hg. For every 100
feet of altitude, barometric pressure drops .10 in. Hg.
If a storm goes through it can change barometric
pressure from what should be present for that alti-
tude. You should know what the average pressure
and corresponding barometric pressure is for your
area.
14 - 44 FUEL INJECTION - GASOLINEBR/BE
INTAKE AIR TEMPERATURE SENSOR (Continued)

REMOVAL - 3.9L/5.2L/5.9L
The MAP sensor is located on the front of the
throttle body (Fig. 36). An L-shaped rubber fitting is
used to connect the MAP sensor to throttle body (Fig.
37).The MAP sensor is located on the front of the
throttle body (Fig. 36). An L-shaped rubber fitting is
used to connect the MAP sensor to throttle body (Fig.
37).
(1) Remove air cleaner assembly.
(2) Remove two MAP sensor mounting bolts
(screws) (Fig. 36).
(3) While removing MAP sensor, slide the vacuum
rubber L-shaped fitting (Fig. 37) from the throttle
body.
(4) Remove rubber L-shaped fitting from MAP sen-
sor.
REMOVAL - 8.0L
The MAP sensor is mounted into the right upper
side of the intake manifold (Fig. 38). A rubber gasket
is used to seal the sensor to the intake manifold. The
rubber gasket is part of the sensor and is not ser-
viced separately.
(1) Remove the electrical connector at the sensor.
(2) Clean the area around the sensor before
removal.
(3) Remove the two sensor mounting bolts.
(4) Remove the sensor from the intake manifold.
INSTALLATION - 3.9L/5.2L/5.9L
The MAP sensor is located on the front of the
throttle body (Fig. 36). An L-shaped rubber fitting is
used to connect the MAP sensor to throttle body (Fig.
37).
(1) Install rubber L-shaped fitting to MAP sensor.
(2) Position sensor to throttle body while guiding
rubber fitting over throttle body vacuum nipple.
Fig. 36 MAP Sensor LocationÐ3.9L/5.2L/5.9L
Engines
1 - MAP SENSOR
2 - MOUNTING SCREWS (2)
Fig. 37 MAP Sensor L-Shaped Rubber FittingÐ3.9L/
5.2L/5.9L Engines
1 - MAP SENSOR
2 - RUBBER FITTING
3 - IDLE AIR PASSAGE
Fig. 38 MAP Sensor LocationÐ8.0L V-10 EngineÐ
Typical
1 - MAP SENSOR
2 - MOUNTING BOLTS
3 - THROTTLE BODY
BR/BEFUEL INJECTION - GASOLINE 14 - 45
MANIFOLD ABSOLUTE PRESSURE SENSOR (Continued)

(3) Install MAP sensor mounting bolts (screws).
Tighten screws to 3 N´m (25 in. lbs.) torque.
(4) Install air cleaner.
INSTALLATION - 8.0L
The MAP sensor is mounted into the right upper
side of the intake manifold (Fig. 38). A rubber gasket
is used to seal the sensor to the intake manifold. The
rubber gasket is part of the sensor and is not ser-
viced separately.
(1) Check the condition of the sensor seal. Clean
the sensor and lubricate the rubber gasket with clean
engine oil.
(2) Clean the sensor opening in the intake mani-
fold.
(3) Install the sensor into the intake manifold.
(4) Install sensor mounting bolts. Tighten bolts to
2 N´m (20 in. lbs.) torque.
(5) Install the electrical connector to sensor.
O2 SENSOR
DESCRIPTION
The Oxygen Sensors (O2S) are attached to, and
protrude into the vehicle exhaust system. Depending
on the emission package, the vehicle may use a total
of either 2 or 4 sensors.
3.9L/5.2L/Light Duty 5.9L Engine:Four sensors
are used: 2 upstream (referred to as 1/1 and 2/1) and
2 downstream (referred to as 1/2 and 2/2). With this
emission package, the right upstream sensor (2/1) is
located in the right exhaust downpipe just before the
mini-catalytic convertor. The left upstream sensor
(1/1) is located in the left exhaust downpipe just
before the mini-catalytic convertor. The right down-
stream sensor (2/2) is located in the right exhaust
downpipe just after the mini-catalytic convertor, and
before the main catalytic convertor. The left down-
stream sensor (1/2) is located in the left exhaust
downpipe just after the mini-catalytic convertor, and
before the main catalytic convertor.
Medium and Heavy Duty 8.0L V-10 Engine:
Four sensors are used (2 upstream, 1 pre-catalyst
and 1 post-catalyst). With this emission package, the
1/1 upstream sensor (left side) is located in the left
exhaust downpipe before both the pre-catalyst sensor
(1/2), and the main catalytic convertor. The 2/1
upstream sensor (right side) is located in the right
exhaust downpipe before both the pre-catalyst sensor
(1/2), and the main catalytic convertor. The pre-cata-
lyst sensor (1/2) is located after the 1/1 and 2/1 sen-
sors, and just before the main catalytic convertor.
The post-catalyst sensor (1/3) is located just after the
main catalytic convertor.Heavy Duty 5.9L Engine:Two sensors are used.
They arebothreferred to as upstream sensors (left
side is referred to as 1/1 and right side is referred to
as 2/1). With this emission package, a sensor is
located in each of the exhaust downpipes before the
main catalytic convertor.
OPERATION
An O2 sensor is a galvanic battery that provides
the PCM with a voltage signal (0-1 volt) inversely
proportional to the amount of oxygen in the exhaust.
In other words, if the oxygen content is low, the volt-
age output is high; if the oxygen content is high the
output voltage is low. The PCM uses this information
to adjust injector pulse-width to achieve the
14.7±to±1 air/fuel ratio necessary for proper engine
operation and to control emissions.
The O2 sensor must have a source of oxygen from
outside of the exhaust stream for comparison. Cur-
rent O2 sensors receive their fresh oxygen (outside
air) supply through the wire harness. This is why it
is important to never solder an O2 sensor connector,
or pack the connector with grease.
Four wires (circuits) are used on each O2 sensor: a
12±volt feed circuit for the sensor heating element; a
ground circuit for the heater element; a low-noise
sensor return circuit to the PCM, and an input cir-
cuit from the sensor back to the PCM to detect sen-
sor operation.
Oxygen Sensor Heaters/Heater Relays:
Depending on the emissions package, the heating ele-
ments within the sensors will be supplied voltage
from either the ASD relay, or 2 separate oxygen sen-
sor relays. Refer to 8, Wiring Diagrams to determine
which relays are used.
The O2 sensor uses a Positive Thermal Co-efficient
(PTC) heater element. As temperature increases,
resistance increases. At ambient temperatures
around 70ÉF, the resistance of the heating element is
approximately 4.5 ohms. As the sensor's temperature
increases, resistance in the heater element increases.
This allows the heater to maintain the optimum
operating temperature of approximately 930É-1100ÉF
(500É-600É C). Although the sensors operate the
same, there are physical differences, due to the envi-
ronment that they operate in, that keep them from
being interchangeable.
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 cer-
tain O2 sensor input(s) 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
14 - 46 FUEL INJECTION - GASOLINEBR/BE
MANIFOLD ABSOLUTE PRESSURE SENSOR (Continued)

on preprogrammed (fixed) values and inputs from
other sensors.
Upstream Sensors:Two upstream sensors are
used (1/1 and 2/1). The 1/1 sensor is the first sensor
to receive exhaust gases from the #1 cylinder. They
provide an input voltage to the PCM. The input tells
the PCM the oxygen content of the exhaust gas. The
PCM uses this information to fine tune fuel delivery
to maintain the correct oxygen content at the down-
stream oxygen sensors. The PCM will change the air/
fuel ratio until the upstream sensors input a voltage
that the PCM has determined will make the down-
stream sensors output (oxygen content) correct.
The upstream oxygen sensors also provide an input
to determine mini-catalyst efficiency. Main catalytic
convertor efficiency is not calculated with this pack-
age.
Downstream Sensors:Two downstream sensors
are used (1/2 and 2/2). The downstream sensors are
used to determine the correct air-fuel ratio. As the
oxygen content changes at the downstream sensor,
the PCM calculates how much air-fuel ratio change is
required. The PCM then looks at the upstream oxy-
gen sensor voltage, and changes fuel delivery until
the upstream sensor voltage changes enough to cor-
rect the downstream sensor voltage (oxygen content).
The downstream oxygen sensors also provide an
input to determine mini-catalyst efficiency. Main cat-
alytic convertor efficiency is not calculated with this
package.
Medium and Heavy Duty 8.0L V-10 Engine:
Four oxygen sensors are used (2 upstream, 1 pre-cat-
alyst and 1 post-catalyst). The upstream sensors (1/1
and 2/1) will fine-tune the air-fuel ratio through the
Powertrain Control Module (PCM). The pre-catalyst
(1/2) and post-catalyst (1/3) sensors will determine
catalytic convertor efficiency (efficiency of the main
catalytic convertor). This is also done through the
PCM.
Heavy Duty 5.9L Engine:Downstream sensors
are not used with this emissions package, meaning
catalytic convertor efficiency is not calculated with
this package. Two upstream sensors are used. The
left upstream sensor (1/1) will monitor cylinders 1, 3,
5 and 7. The right upstream sensor (2/1) will monitor
cylinders 2, 4, 6 and 8. The PCM monitors the oxy-
gen content of the sensors, and will fine-tune the air-
fuel ratio.
Engines equipped with either a downstream sen-
sor(s), or a post-catalytic sensor, will monitor cata-
lytic convertor efficiency. If efficiency is below
emission standards, the Malfunction Indicator Lamp
(MIL) will be illuminated and a Diagnostic Trouble
Code (DTC) will be set. Refer to Monitored Systems
in Emission Control Systems for additional informa-
tion.REMOVAL
Never apply any type of grease to the oxygen
sensor electrical connector, or attempt any sol-
dering of the sensor wiring harness. For sensor
operation, it must have a comparison source of
oxygen from outside the exhaust system. This
fresh air is supplied to the sensor through its
pigtail wiring harness.
The O2S (oxygen sensors) are numbered 1/1, 1/2,
1/3, 2/1 and 2/2.
On HDC engines, the pre-catalyst/post catalyst
O2S sensors are located at the inlet and outlet ends
of the catalytic converter (Fig. 39).
The 1/1 and 2/1 sensors are located before the
mini-cats (Fig. 40). The 1/2 and 2/2 sensors are
located after the mini-cats (Fig. 40).
Fig. 39 Pre-catalyst/Post catalyst Oxygen SensorsÐ
HDC Engines
1 - POST CATALYST OXYGEN SENSOR (1/3)
2 - PRE-CATALYST OXYGEN SENSOR (1/2)
Fig. 40 Oxygen SensorsÐ5.2L/5.9L California
Engines
BR/BEFUEL INJECTION - GASOLINE 14 - 47
O2 SENSOR (Continued)

WARNING: THE EXHAUST MANIFOLD, EXHAUST
PIPES AND CATALYTIC CONVERTER BECOME
VERY HOT DURING ENGINE OPERATION. ALLOW
ENGINE TO COOL BEFORE REMOVING OXYGEN
SENSOR.
(1) Raise and support the vehicle.
(2) Disconnect the wire connector from the O2S
sensor.
CAUTION: When disconnecting the sensor electrical
connector, do not pull directly on wire going into
sensor.
(3) Remove the O2S sensor with an oxygen sensor
removal and installation tool.
INSTALLATION
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 the O2S sensor. Tighten to 30 N´m (22
ft. lbs.) torque.
(2) Connect the O2S sensor wire connector.
(3) Lower the vehicle.
PTO SWITCH
DESCRIPTION
This Powertrain Control Module (PCM) input is
used only on models equipped with aftermarket
Power Take Off (PTO) units.
OPERATION
The input is used only to tell the PCM that the
PTO has been engaged. The PCM will disable (tem-
porarily shut down) certain OBD II diagnostic trou-
ble codes when the PTO is engaged.
When the aftermarket PTO switch has been
engaged, a 12V + signal is sent through circuit G113
to PCM pin A13. The PCM will then sense and deter-
mine that the PTO has been activated.
THROTTLE BODY
DESCRIPTION
The throttle body is located on the intake manifold.
Fuel does not enter the intake manifold through the
throttle body. Fuel is sprayed into the manifold by
the fuel injectors.
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 - 3.9L/5.2L/5.9L
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 powertrain control module (PCM).
(1) Remove the air cleaner.
(2) Disconnect throttle body electrical connectors
at MAP sensor, IAC motor and TPS (Fig. 41).
(3) Remove vacuum line at throttle body.
(4) Remove all control cables from throttle body
(lever) arm. Refer to the Accelerator Pedal and Throt-
tle Cable section of this group for additional informa-
tion.
Fig. 41 Sensor Electrical ConnectorsÐ3.9L/5.2L/5.9L
EnginesÐTypical
1 - MAP SENSOR
2 - IDLE AIR CONTROL MOTOR
3 - THROTTLE POSITION SENSOR
14 - 48 FUEL INJECTION - GASOLINEBR/BE
O2 SENSOR (Continued)

(5) Remove four throttle body mounting bolts (Fig.
42).
(6) Remove throttle body from intake manifold.
(7) Discard old throttle body-to-intake manifold
gasket.
REMOVAL - 8.0L
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 powertrain control module (PCM).
(1) Remove the air cleaner cover.
(2) Remove the 4 air cleaner housing mounting
nuts and remove housing from throttle body.
(3) Disconnect throttle body electrical connectors
at the IAC motor and TPS.
(4) Remove all control cables from throttle body
(lever) arm. Refer to the Accelerator Pedal and Throt-
tle Cable section of this group for additional informa-
tion.
(5) Remove four throttle body mounting nuts (Fig.
43).
(6) Remove throttle body from intake manifold.
(7) Discard old throttle body-to-intake manifold
gasket.
INSTALLATION - 3.9L/5.2L/5.9L
A (factory adjusted) set screw is used to mechani-
cally limit the position of the throttle body throttleplate.Never attempt to adjust the engine idle
speed using this screw.All idle speed functions are
controlled by the powertrain control module (PCM).
(1) Clean the mating surfaces of the throttle body
and the intake manifold.
(2) Install new throttle body-to-intake manifold
gasket.
(3) Install throttle body to intake manifold.
(4) Install four mounting bolts. Tighten bolts to 23
N´m (200 in. lbs.) torque.
(5) Install control cables.
(6) Install vacuum line to throttle body.
(7) Install electrical connectors.
(8) Install air cleaner.
INSTALLATION - 8.0L
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 powertrain control module (PCM).
(1) Clean the mating surfaces of the throttle body
and the intake manifold.
(2) Install new throttle body-to-intake manifold
gasket.
(3) Install throttle body to intake manifold.
(4) Install four mounting nuts. Tighten nuts to 22
N´m (192 in. lbs.) torque.
Fig. 42 Throttle Body
1 - THROTTLE BODY MOUNTING BOLTS (4)
2 - THROTTLE BODY
Fig. 43 Throttle Body Mounting NutsÐ8.0L Engine
1 - INTAKE MANIFOLD UPPER HALF
2 - GASKET
3 - THROTTLE BODY
4 - MOUNTING NUTS (4)
BR/BEFUEL INJECTION - GASOLINE 14 - 49
THROTTLE BODY (Continued)

(5) Install control cables.
(6) Install electrical connectors.
(7) Install air cleaner housing to throttle body.
(8) Install 4 air cleaner housing mounting nuts.
Tighten nuts to 11 N´m (96 in. lbs.) torque.
(9) Install air cleaner housing cover.
THROTTLE CONTROL CABLE
REMOVAL
CAUTION: Be careful not to damage or kink the
cable core wire (within the cable sheathing) while
servicing accelerator pedal or cables.
(1) From inside the vehicle, hold up the accelerator
pedal. Remove the plastic cable retainer and throttle
cable core wire from upper end of pedal arm (Fig.
21). The plastic cable retainer snaps into pedal the
arm.
(2) Remove the cable core wire at the pedal arm.
(3) Remove the air cleaner housing.
(4) From inside the vehicle, pinch both sides of the
plastic cable housing retainer tabs at the dash panel
(Fig. 21).
(5) Remove cable housing from dash panel and
pull the cable into the engine compartment.
(6)3.9L/5.2L/5.9L Engines:Disconnect the cable
from the routing/holddown clip at the radiator fan
shroud.
(7)8.0L V-10 Engine:Remove the throttle cable
socket at throttle lever ball. (Fig. 45) (snaps off).
(8)3.9L/5.2L/5.9L Engines:Slip the cable end
rearward from pin on throttle body (Fig. 44).
(9) Remove cable housing at throttle body mount-
ing bracket by pressing on release tab with a small
screwdriver (Fig. 46) or (Fig. 45).To prevent cable
housing breakage, press on the tab only enough
to release the cable from the bracket.Lift the
cable housing straight up from bracket while press-
ing on release tab. Remove throttle cable from vehi-
cle.
INSTALLATION
(1)3.9L/5.2L/5.9L Engines:
(a) Rotate and hold the throttle cam in the full
wide open position. Snap the cable end onto lever
pin (Fig. 44).
(b) Connect cable to throttle body mounting
bracket (push down and lock).
(c) Connect cable to fan shroud routing clip.
(2)8.0L V-10 Engine:
(a) Connect cable end socket to throttle body
lever ball (snaps on) (Fig. 45).
(b) Connect cable to throttle body mounting
bracket (push down and lock).
Fig. 44 Throttle Cable at Throttle BodyÐ3.9L/5.2L/
5.9L EnginesÐTypical
1 - THROTTLE LEVER PIN
2 - CAM (V-8 ENGINE ONLY)
3 - THROTTLE CABLE END
Fig. 45 Throttle Cable at Throttle BodyÐ8.0L V-10
Engine
1 - PRESS TAB FOR CABLE REMOVAL
2 - THROTTLE CABLE
3 - CABLE SOCKET
4 - LEVER BALL
5 - MOUNTING BRACKET
14 - 50 FUEL INJECTION - GASOLINEBR/BE
THROTTLE BODY (Continued)

(3) Install the remaining cable housing end into
and through the dash panel opening (snaps into posi-
tion). The two plastic pinch tabs (Fig. 21) should lock
the cable to dash panel.
(4) From inside the vehicle, hold up the accelera-
tor pedal. Install the throttle cable core wire and
plastic cable retainer into and through the upper end
of the pedal arm (the plastic retainer is snapped into
the pedal arm). When installing the plastic retainer
to the accelerator pedal arm, note the index tab on
the pedal arm (Fig. 21). Align the index slot on the
plastic cable retainer to this index tab.
THROTTLE POSITION SENSOR
DESCRIPTION
The 3±wire Throttle Position Sensor (TPS) is
mounted on the throttle body and is connected to the
throttle blade.
OPERATION
The TPS is a 3±wire variable resistor that provides
the Powertrain Control Module (PCM) with an input
signal (voltage) that represents the throttle blade
position of the throttle body. The sensor is connected
to the throttle blade shaft. As the position of the
throttle blade changes, the resistance (output volt-
age) of the TPS changes.The PCM supplies approximately 5 volts to the
TPS. The TPS output voltage (input signal to the
PCM) represents the throttle blade position. The
PCM receives an input signal voltage from the TPS.
This will vary in an approximate range of from .26
volts at minimum throttle opening (idle), to 4.49 volts
at wide open throttle. Along with inputs from other
sensors, the PCM uses the TPS input to determine
current engine operating conditions. In response to
engine operating conditions, the PCM will adjust fuel
injector pulse width and ignition timing.
The PCM needs to identify the actions and position
of the throttle blade at all times. This information is
needed to assist in performing the following calcula-
tions:
²Ignition timing advance
²Fuel injection pulse-width
²Idle (learned value or minimum TPS)
²Off-idle (0.06 volt)
²Wide Open Throttle (WOT) open loop (2.608
volts above learned idle voltage)
²Deceleration fuel lean out
²Fuel cutoff during cranking at WOT (2.608 volts
above learned idle voltage)
²A/C WOT cutoff (certain automatic transmis-
sions only)
REMOVAL - 3.9L/5.2L/5.9L
The TPS is located on the side of the throttle body.
(1) Remove air intake tube at throttle body.
(2) Disconnect TPS electrical connector.
(3) Remove two TPS mounting bolts (Fig. 47).
(4) Remove TPS from throttle body.
Fig. 46 Cable Release
1-TAB
Fig. 47 TPS Mounting BoltsÐ3.9L/5.2L/5.9L Engines
1 - THROTTLE POSITION SENSOR
2 - MOUNTING SCREWS
BR/BEFUEL INJECTION - GASOLINE 14 - 51
THROTTLE CONTROL CABLE (Continued)

REMOVAL - 8.0L
The TPS is located on the side of the throttle body
(Fig. 48).
(1) Remove air intake tube at air cleaner housing.
(2) Remove the air cleaner cover.
(3) Remove the 4 air cleaner housing mounting
nuts and remove housing from throttle body.
(4) Disconnect TPS electrical connector.
(5) Remove two TPS mounting bolts (Fig. 48).
(6) Remove TPS from throttle body.
INSTALLATION - 3.9L/5.2L/5.9L
The throttle shaft end of the throttle body slides
into a socket in the TPS (Fig. 49). The TPS must be
installed so that it can be rotated a few degrees. If
the sensor will not rotate, install the sensor with the
throttle shaft on the other side of the socket tangs.
The TPS will be under slight tension when rotated.
(1) Install the TPS and two retaining bolts.
(2) Tighten bolts to 7 N´m (60 in. lbs.) torque.
(3) Manually operate the throttle control lever by
hand to check for any binding of the TPS.
(4) Connect TPS electrical connector to TPS.
(5) Install air intake tube.
INSTALLATION - 8.0L
The throttle shaft end of the throttle body slides
into a socket in the TPS (Fig. 50). The TPS must beinstalled so that it can be rotated a few degrees. If
the sensor will not rotate, install the sensor with the
throttle shaft on the other side of the socket tangs.
The TPS will be under slight tension when rotated.
(1) Install the TPS and two retaining bolts.
(2) Tighten bolts to 7 N´m (60 in. lbs.) torque.
(3) Manually operate the throttle control lever by
hand to check for any binding of the TPS.
(4) Connect TPS electrical connector to TPS.
(5) Install air cleaner housing to throttle body.
(6) Install 4 air cleaner housing mounting nuts.
Tighten nuts to 11 N´m (96 in. lbs.) torque.
(7) Install air cleaner housing cover.
(8) Install air intake tube to cover.
Fig. 48 TPS Mounting BoltsÐ8.0L Engine
1 - MOUNTING BOLTS (2)
2 - IDLE AIR CONTROL MOTOR
3 - THROTTLE POSITION SENSOR
4 - THROTTLE BODY
Fig. 49 InstallationÐ3.9L/5.2L/5.9L EnginesÐTypical
1 - THROTTLE BODY
2 - THROTTLE POSITION SENSOR
3 - THROTTLE SHAFT
4 - SOCKET LOCATING TANGS
Fig. 50 InstallationÐTypical Mounting
1 - THROTTLE BODY
2 - THROTTLE POSITION SENSOR
3 - THROTTLE SHAFT
4 - SOCKET LOCATING TANGS
14 - 52 FUEL INJECTION - GASOLINEBR/BE
THROTTLE POSITION SENSOR (Continued)

FUEL INJECTOR
DESCRIPTION
A separate fuel injector (Fig. 51) is used for each
individual cylinder.
OPERATION
The fuel injectors are electrical solenoids. The
injector contains a pintle that closes off an orifice at
the nozzle end. When electric current is supplied to
the injector, the armature and needle move a short
distance against a spring, allowing fuel to flow out
the orifice. Because the fuel is under high pressure, a
fine spray is developed in the shape of a pencil
stream. The spraying action atomizes the fuel, add-
ing it to the air entering the combustion chamber.
An individual fuel injector is used for each individ-
ual cylinder. The top (fuel entry) end of the injector is
attached into an opening on the fuel rail.
The nozzle (outlet) ends of the injectors are posi-
tioned into openings in the intake manifold just above
the intake valve ports of the cylinder head. The engine
wiring harness connector for each fuel injector is
equipped with an attached numerical tag (INJ 1, INJ 2
etc.). This is used to identify each fuel injector.
The injectors are energized individually in a
sequential order by the Powertrain Control Module
(PCM). The PCM will adjust injector pulse width by
switching the ground path to each individual injector
on and off. Injector pulse width is the period of time
that the injector is energized. The PCM will adjust
injector pulse width based on various inputs it
receives.
Battery voltage is supplied to the injectors through
the ASD relay.
The PCM determines injector pulse width based on
various inputs.
OPERATION - PCM OUTPUT
The nozzle ends of the injectors are positioned into
openings in the intake manifold just above the intake
valve ports of the cylinder head. The engine wiring
harness connector for each fuel injector is equipped
with an attached numerical tag (INJ 1, INJ 2 etc.).
This is used to identify each fuel injector with its
respective cylinder number.
The injectors are energized individually in a
sequential order by the Powertrain Control Module
(PCM). The PCM will adjust injector pulse width by
switching the ground path to each individual injector
on and off. Injector pulse width is the period of time
that the injector is energized. The PCM will adjust
injector pulse width based on various inputs it
receives.
Battery voltage (12 volts +) is supplied to the injec-
tors through the ASD relay. The ASD relay will shut-
down the 12 volt power source to the fuel injectors if
the PCM senses the ignition is on, but the engine is
not running. This occurs after the engine has not
been running for approximately 1.8 seconds.
The PCM determines injector on-time (pulse width)
based on various inputs.
DIAGNOSIS AND TESTING - FUEL INJECTOR
TEST
To perform a complete test of the fuel injectors and
their circuitry, use the DRB scan tool and refer to the
appropriate Powertrain Diagnostics Procedures man-
ual. To test the injector only, refer to the following:
Disconnect the fuel injector wire harness connector
from the injector. The injector is equipped with 2
electrical terminals (pins). Place an ohmmeter across
the terminals. Resistance reading should be approxi-
mately 12 ohms61.2 ohms at 20ÉC (68ÉF).
REMOVAL
(1) Remove air cleaner assembly.
(2) Remove fuel injector rail assembly. Refer to
Fuel Injector Rail removal in this section.
(3) Remove the clip(s) retaining the injector(s) to
fuel rail (Fig. 30) or (Fig. 31).
(4) Remove injector(s) from fuel rail.
INSTALLATION
(1) Apply a small amount of engine oil to each fuel
injector o-ring. This will help in fuel rail installation.
(2) Install injector(s) and injector clip(s) to fuel
rail.
(3) Install fuel rail assembly. Refer to Fuel Injector
Rail installation.
(4) Install air cleaner.
(5) Start engine and check for leaks.
Fig. 51 Fuel Injector
1 - FUEL INJECTOR
2 - NOZZLE
3 - TOP (FUEL ENTRY)
BR/BEFUEL INJECTION - GASOLINE 14 - 53