Temperature sensor location DODGE RAM 2001 Service User Guide

With the transmitter mounted in the storage bin,
adapter pegs located on the garage door opener push
button unit are selected and mounted on one of two
posts on the back side of the push button. The com-
bination of the adapter peg length and the push but-
ton post location must be suitable to depress the
button of the transmitter when the push button in
the center of the garage door opener storage bin door
is depressed. When the proper combination has been
selected, the push button is reinstalled in the com-
partment and the compartment door is closed.
SUNGLASS STORAGE BIN
A sunglasses storage bin is included in the over-
head console. The storage bin is located near the rear
of the overhead console and is held in the closed posi-
tion by a latch that is integral to the storage bin
door. The interior of the bin is lined with a foam rub-
ber padding material to protect the sunglasses from
being scratched. Dampening springs that are located
on the back of the overhead console reading and
courtesy lamp housing contact the hinges of the sun-
glasses storage bin for a smooth opening action.
The sunglasses storage bin and door unit is avail-
able for service replacement. The hinge dampening
springs are serviced as a unit with the overhead con-
sole reading and courtesy lamp housing.
The sunglasses storage bin is opened by pressing
the latch on the rear edge of the door towards the
front of the vehicle, then pulling the bin downward to
the open position. The integral latch on the sun-
glasses bin door will automatically engage when the
bin is closed. See the owner's manual in the vehicle
glove box for more information on the use and oper-
ation of the sunglasses storage bin.
COMPASS
While in the compass/temperature mode, the com-
pass will display the direction in which the vehicle is
pointed using the eight major compass headings
(Examples: north is N, northeast is NE), along with
the outside ambient temperature. When the compass
unit is placed in the compass/compass in degreesmode, the compass will display the direction the
vehicle is heading using the eight major compass
headings and in degrees (0 to 359 degrees). North is
0 degrees, East is 90 degrees, South is 180 degrees
and West is 270 degrees. It will not display the head-
ings in minutes or seconds.
The self-calibrating compass unit requires no
adjusting in normal use. The compass unit will com-
pensate for magnetism the body of the vehicle may
acquire during normal use. However, avoid placing
anything magnetic directly on the roof of the vehicle.
Magnetic mounts for an antenna, a repair order hat,
or a funeral procession flag can exceed the compen
sating ability of the compass unit if placed on the
roof panel. If the vehicle roof should become magne-
tized, the demagnetizing and calibration procedures
found in this group may be required to restore proper
compass operation.
THERMOMETER
The thermometer displays the outside ambient
temperature in whole degrees. The temperature dis-
play can be changed from Fahrenheit to Celsius
using the U.S./Metric push button. The displayed
temperature is not an instant reading of conditions,
but an average temperature. It may take the ther-
mometer display several minutes to respond to a
major temperature change, such as driving out of a
heated garage into winter temperatures.
When the ignition switch is turned to the Off posi-
tion, the last displayed temperature reading stays in
the thermometer unit memory. When the ignition
switch is turned to the On position again, the ther-
mometer will display the memory temperature if the
engine coolant temperature is above about 43É C
(109É F). If the engine coolant temperature is below
about 43É C (109É F), the thermometer will display
the actual temperature sensed by the ambient tem-
perature sensor. The thermometer temperature dis-
play update interval varies with the vehicle speed;
therefore, if the temperature reading seems inaccu-
rate, drive the vehicle for at least three minutes
1 - SUNGLASSES STORAGE BIN
2 - GARAGE DOOR OPENER STORAGE BIN DOOR
3 - COMPUTER LENS OR COVER PLUG
4 - HOOK AND LOOP FASTENER
5 - SECURITY INDICATOR LAMP
6 - COMPASS MINI-TRIP COMPUTER MODULE
7 - SCREW (3)
8 - SCREW (4)
9 - BULB HOLDERS
10 - SWITCHES11 - WIRE HARNESS
12 - SPRINGS (2)
13 - READING AND COURTESY LAMP HOUSING
14 - REFLECTORS
15 - OVERHEAD CONSOLE HOUSING
16 - LENSES
17 - BUMPER
18 - GARAGE DOOR OPENER PUSH BUTTON
BR/BEMESSAGE SYSTEMS 8M - 3
OVERHEAD CONSOLE (Continued)

while maintaining a speed of 48 kilometers-per-hour
(30 miles-per-hour) or higher.
The thermometer function is supported by an
ambient temperature sensor. The sensor is mounted
outside the passenger compartment near the front
and center of the vehicle, and is hard wired to the
module. The ambient temperature sensor is available
as a separate service item.
STANDARD PROCEDURE - COMPASS
CALIBRATION
CAUTION: Do not place any external magnets, such
as magnetic roof mount antennas, in the vicinity of
the compass. Do not use magnetic tools when ser-
vicing the overhead console.
The electronic compass unit features a self-cali-
brating design, which simplifies the calibration pro-
cedure. This feature automatically updates the
compass calibration while the vehicle is being driven.
This allows the compass unit to compensate for small
changes in the residual magnetism that the vehicle
may acquire during normal use. If the compass read-
ings appear to be erratic or out of calibration, per-
form the following calibration procedure. Also, new
service replacement compass mini-trip computer
modules must have their compass calibrated using
this procedure. Do not attempt to calibrate the com-
pass near large metal objects such as other vehicles,
large buildings, or bridges; or, near overhead or
underground power lines.
(1) Start the engine. If the compass/temperature
data is not currently being displayed, momentarily
depress and release the Step push button to step
through the display options until you have reached
the compass/temperature display.
(2) Depress both the U.S./Metric and the Step
push buttons at the same time for more than six sec-
onds, until ªCALº appears in the display, then release
both push buttons. The ªCALº in the display indi-
cates that the compass is in the calibration mode.
(3) Drive the vehicle on a level surface, at least
fifty feet away from large metal objects and power
lines, in all four compass directions, such as driving
around a city block several times or driving in two to
three complete circles at a slow to medium speed.
(4) When the calibration is successfully completed,
ªCALº will disappear from the display and normal
compass mini-trip computer operation will resume.
NOTE: If the ªCALº message remains in the display,
either there is excessive magnetism near the com-
pass, or the unit is faulty. Repeat the calibration
procedure at least one more time.NOTE: If the wrong direction is still indicated in the
compass display, the area selected for calibration
may be too close to a strong magnetic field. Repeat
the calibration procedure in another location.
STANDARD PROCEDURE - COMPASS
VARIATION ADJUSTMENT
Compass variance, also known as magnetic decli-
nation, is the difference in angle between magnetic
north and true geographic north. In some geographic
locations, the difference between magnetic and geo-
graphic north is great enough to cause the compass
to give false readings. If this problem occurs, the
compass variance must be set. There are two meth-
ods that can be used to enter this information into
the compass mini-trip computer module. They are
the zone method and the direct method.
ZONE METHOD
(1) Using the Variance Settings map, find your
geographic location and note the zone number (Fig.
2).
(2) Turn the ignition switch to the On position. If
the compass/temperature data is not currently being
displayed, momentarily depress and release the Step
push button to step through the display options until
you have reached the compass/temperature display.
(3) Depress both the U.S./Metric and the Step
push buttons at the same time and hold them down
for more than 100 milliseconds, but not more than
one second. The compass mini-trip computer will
enter the variation adjustment mode and ªVARº
along with the current variance zone will appear in
the display.
(4) Momentarily depress and release the Step push
button to step through the zone numbers, until the
zone number for your geographic location appears in
the display.
(5) After five seconds, the displayed zone will auto-
matically be set in the compass mini-trip computer
module memory and normal operation will resume.
(6) Confirm that the correct directions are now
indicated by the compass.
DIRECT METHOD
(1) Turn the vehicle so it is headed in either the
north or south direction. The vehicle must be headed
within 45 degrees of north or south for this procedure
to work. The vehicle may be moving or stationary.
(2) Turn the ignition switch to the On position. If
the compass/temperature data is not currently being
displayed, momentarily depress and release the Step
push button to step through the display options until
you have reached the compass/temperature display.
8M - 4 MESSAGE SYSTEMSBR/BE
OVERHEAD CONSOLE (Continued)

NOTE: If the compass functions, but accuracy is
suspect, it may be necessary to perform a variation
adjustment. This procedure allows the compass
unit to accommodate variations in the earth's mag-
netic field strength, based on geographic location.
Refer to Compass Variation Adjustment in the Ser-
vice Procedures section of this group.
NOTE: If the compass reading has blanked out, and
only ªCALº appears in the display, demagnetizing
may be necessary to remove excessive residual
magnetic fields from the vehicle. Refer to Compass
Demagnetizing in the Service Procedures section of
this group.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the overhead console from the head-
liner. Refer toOverhead Consolein the Removal
and Installation section of this group for the proce-
dures.
(3) Remove the three screws that secure the com-
pass mini-trip computer module to the overhead con-
sole housing (Fig. 7).
(4) Pull the compass mini-trip computer module
away from the overhead console far enough to access
the wire harness connector.
(5) Disconnect the overhead console wire harness
connector from the compass mini-trip computer mod-
ule connector receptacle.
(6) Remove the compass mini-trip computer mod-
ule from the overhead console housing.
INSTALLATION
(1) Position the compass mini-trip computer mod-
ule onto the overhead console housing.
(2) Reconnect the overhead console wire harness
connector to the compass mini-trip computer module
connector receptacle.
(3) Install and tighten the three screws that secure
the compass mini-trip computer module to the over-
head console housing. Tighten the screws to 2.2 N´m
(20 in. lbs.).
(4) Install the overhead console onto the headliner.
Refer toOverhead Consolein the Removal and
Installation section of this group for the procedures.
(5) Reconnect the battery negative cable.
NOTE: If a new compass mini-trip computer has
been installed, the compass will have to be cali-
brated and the variance set. Refer to Compass Vari-
ation Adjustment and Compass Calibration in the
Service Procedures section of this group for the
procedures.
AMBIENT TEMP SENSOR
DESCRIPTION
Ambient air temperature is monitored by the com-
pass mini-trip computer module through the ambient
temperature sensor. The ambient temperature sensor
is a variable resistor mounted to a bracket that is
secured with a screw to the underside of the hood
panel near the hood latch striker in the engine com-
partment.
For complete circuit diagrams, refer toOverhead
Consolein the Contents of Wiring Diagrams. The
ambient temperature sensor cannot be adjusted or
repaired and, if faulty or damaged, it must be
replaced.
OPERATION
The ambient temperature sensor is a variable
resistor that operates on a five-volt reference signal
sent to it by the compass mini-trip computer module.
The resistance in the sensor changes as temperature
changes, changing the return circuit voltage to the
compass mini-trip computer module. Based upon the
resistance in the sensor, the compass mini-trip com-
puter module senses a specific voltage on the return
circuit, which it is programmed to correspond to a
specific temperature.Fig. 7 Compass Mini-Trip Computer
1 - WIRE HARNESS CONNECTOR
2 - SCREWS (3)
3 - COMPASS MINI-TRIP COMPUTER MODULE
4 - FRONT LATCHES
BR/BEMESSAGE SYSTEMS 8M - 11
COMPASS/MINI-TRIP COMPUTER (Continued)

8W-90 CONNECTOR/GROUND LOCATIONS
TABLE OF CONTENTS
page
CONNECTOR/GROUND LOCATIONS
DESCRIPTION............................1
CONNECTOR/GROUND
LOCATIONS
DESCRIPTION
This section provides illustrations identifying con-
nector and ground locations in the vehicle. A connec-tor and ground index is provided. Use the wiring
diagrams in each section for connector and ground
identification. Refer to the index for the proper figure
number. For items that are not shown in this section
N/S is placed in the Fig. column.
Connector Name/Number Color Location Fig.
4WD Switch BK On Front Axle N/S
A/C Compressor Clutch BK Rear of A/C Compressor 4,5,6,8
A/C Heater Control BK Center of Instrument Panel 25
A/C Heater Temperature Select NAT Center of Instrument Panel 25
A/C High Pressure Switch BK At A/C Compressor 4,5,6,8
A/C Low Pressure Switch BK Top of A/C Accumulator 1,2
Accelerator Pedal Position Sensor (Diesel) Left Front of Engine 10,11
Aftermarket Trailer Tow Connector Rear of Vehicle N/S
Airbag Control Module Center of I.P. at Airbag Control
Module23
Ambient Temperature Sensor BK Radiator Left Support N/S
Ash Receiver Lamp Center of Instrument Panel 26
Back-up Lamp Switch BK Top of Transmission 13
Battery Temperature Sensor BK Below Battery Tray 16
Blend Door Actuator Center of Instrument Panel N/S
Blower Motor BK Bottom Right of Instrument Panel 23
Blower Motor Resistor Block BK Bottom Right of Instrument Panel 26
Brake Lamp Switch Brake Pedal Arm 23,24
Brake Pressure Switch At Master Cylinder 14
Bypass Jumper GN Top Of Clutch Pedal 27
C105 Rear of Front Bumper N/S
C106 BK Rear of Front Bumper 17
C114 BK Radiator Left Support 15
C125 (Diesel) BK Left Rear of Engine Compartment 2
C126 (Diesel) GY Left Rear of Engine Compartment 2
C129 BK Above Left Front Body Cushion 15,22
C130 At Power Distribution Center 1,2
C134 BK Left Cowl 23,25,27
BR/BE8W-90 CONNECTOR/GROUND LOCATIONS 8W - 90 - 1

Connector Name/Number Color Location Fig.
Cummins Bus (-) Left Front of Engine 10
Cup Holder Lamp Center of Instrument Panel 23,26
Data Link Connector BK Left Bottom of Instrument Panel 23,24
Day/Night Mirror BK Day/Night Mirror N/S
Daytime Running Lamp Module BK Left Fender Side Shield 14
Dome Lamp Rear of Cab 18
Driver Airbag BK Steering Wheel N/S
Driver Door Arm/Disarm Switch BK In Door 19
Driver Door Jamb Switch NAT Door Jamb 19
Driver Door Lock Motor BK In Door 19
Driver Door Window/Lock Switch BL In Door 19
Driver Heated Seat Module BL Under Seat N/S
Driver Heated Seat Switch RD Center of Instrument Panel N/S
Driver Lumbar Motor Under Seat N/S
Driver Power Seat Front Vertical Motor BK Under Seat N/S
Driver Power Seat Horizontal Motor BK Under Seat N/S
Driver Power Seat Rear Vertical Motor Under Seat N/S
Driver Power Seat Switch At Seat N/S
Driver Power Window Motor In Door 19
Duty Cycle EVAP/Purge Solenoid BK Right Fender Side Shield 17
Electric Brake Provision Bottom Left of Instrument Panel N/S
Engine Control Module (Diesel) Left Side Engine 12
Engine Coolant Temperature Sensor (Diesel) BK Left Front of Cylinder Head
(Diesel)10
Engine Coolant Temperature Sensor (Gas) BK On Thermostat Housing 3,6
Engine Oil Pressure Sensor (V6, V8) BK Near Distributor 3
Engine Oil Pressure Sensor (V10) Near Oil Filter 6
Engine Oil Pressure Sensor (Diesel) Left Side of Engine 12
Fuel Heater (Diesel) Left Side of Engine 10
Fuel Injection Pump (Diesel) Left Side of Engine, Below ECM 10
Fuel Injector No.1 BK At Fuel Injector 4,5
Fuel Injector No. 2 BK At Fuel Injector 4,5,6
Fuel Injector No. 3 BK At Fuel Injector 4,5,6
Fuel Injector No. 4 BK At Fuel Injector 4,5,6
Fuel Injector No. 5 BK At Fuel Injector 4,5,6
Fuel Injector No. 6 BK At Fuel Injector 4,5,6
Fuel Injector No. 7 BK At Fuel Injector 4,6
Fuel Injector No. 8 BK At Fuel Injector 4,6
Fuel Injector No. 9 BK At Fuel Injector 6
Fuel Injector No. 10 BK At Fuel Injector 6
Fuel Pump Module LTGY At Frame Rail 22
Fuel Transfer Pump (Diesel) Left Rear of Engine Bottom of
Pump10
BR/BE8W-90 CONNECTOR/GROUND LOCATIONS 8W - 90 - 3
CONNECTOR/GROUND LOCATIONS (Continued)

Connector Name/Number Color Location Fig.
G100 Left Fender Side Shield 16
G101 Left Fender Side Shield 16
G102 Left Fender Side Shield (RWAL
Ground)N/S
G103 Near T/O for Wiper Motor 14
G105 Front of Engine (Engine Ground) 4,5,6,9
G107 (Diesel) Left Rear of Engine 10
G113 (Diesel) Primary Battery Engine Ground N/S
G114 Battery Engine Ground N/S
G115 (Diesel) Primary Battery Body Ground N/S
G116 Battery Frame Ground N/S
G117 (Diesel) Auxilary Battery Engine Ground N/S
G118 (Diesel) Primary Frame Ground N/S
G120 (Diesel) Auxilary Battery Body Ground N/S
G200 Left Cowl 24
G201 Instrument Panel Right Center
Support23,25
G300 Left Lower Cowl 20
G301 Below Left Rear Speaker 18
G302 At Overhead Console 20
Generator BK Front of Engine 7,8
Glove Box Lamp At Glove Box 23
Headlamp Switch C1 BK Left Side of Instrument Panel 23,26
Headlamp Switch C2 Left Side of Instrument Panel 23,26
Heated Mirror Switch Center of Instrument Panel 25
High Note Horn BK Front Bumper Right Support 17
Idle Air Control Motor BK On Throttle Body 9
Ignition Coil GY Right Front of Engine 4,5,9
Ignition Coil 4 Pack BK Right Side of Engine 9
Ignition Coil 6 Pack BK Right Side of Engine 9
Ignition Switch C1 Steering Column 24
Ignition Switch C2 Steering Column 24
Instrument Cluster C1 Rear of Instrument Cluster 23
Instrument Cluster C2 Rear of Instrument Cluster 23
Intake Air Heater Relay Left Fender Side Shield 16
Intake Air Temperature Sensor (Diesel) Left Rear of Engine 10
Intake Air Temperature Sensor (Gas) GY On Intake Manifold 4,5,6
Joint Connector No. 1 In Power Distribution Center N/S
Joint Connector No. 2 In Power Distribution Center N/S
Joint Connector No. 3 Front Bumper Right support 17
Joint Connector No. 4 Left Front Engine Compartment 16
Joint Connector No. 5 NAT Left Side of Instrument Panel 24
Joint Connector No. 6 NAT Left Side of Instrument Pane 24
8W - 90 - 4 8W-90 CONNECTOR/GROUND LOCATIONSBR/BE
CONNECTOR/GROUND LOCATIONS (Continued)

(24)Remove the high pressure fuel lines (Fig.
18) (Fig. 19) from the engine as follows:
(a) Remove all injection line-to-intake manifold
cover support bracket bolts.
(b) Loosen the #1, 2, and 4 cylinder high pres-
sure lines at the injection pump.
(c) Loosen the #1, 2, and 4 cylinder high pres-
sure lines at the cylinder head.
(d) Remove the #1, 2, and 4 cylinder high pres-
sure line bundle from the engine.
(e) Loosen the #3, 5, and 6 cylinder high pres-
sure lines at the injection pump.
(f) Loosen the #3, 5, and 6 cylinder high pres-
sure lines at the cylinder head.
(g) Remove the #3, 5, and 6 cylinder high pres-
sure line bundle from the engine.
(25) Remove the lift pump-to-fuel filter low pres-
sure line.
(26) Remove the fuel filter-to-injection pump low
pressure line.
(27) Disconnect the water-in-fuel and fuel heater
connectors.
(28) Remove the fuel filter assembly-to-manifold
cover bolts and remove filter assembly from vehicle.
(29) Disconnect the Intake Air Temperature and
Manifold Air Pressure sensor connectors (Fig. 20).
(30) Remove the cylinder head cover (Fig. 21)
(Refer to 9 - ENGINE/CYLINDER HEAD/CYLIN-
DER HEAD COVER(S) - REMOVAL).
(31) Remove the rocker levers (Fig. 22), cross
heads and push rods (Fig. 23). Mark each component
so they can be installed in their original positions.NOTE: The #5 cylinder exhaust and the #6 cylinder
intake and exhaust push rods are removed by lift-
ing them up and through the provided cowl panel
access holes. Remove the rubber plugs to expose
these relief holes.
(32) Remove the fuel return line banjo bolt at the
rear of the cylinder head (Fig. 24). Be careful not to
drop the two (2) sealing washers.
(33) Reinstall the engine lift bracket at the rear of
cylinder head.
(34) Remove twenty six (26) cylinder head-to-block
bolts.
(35) Attach an engine lift crane to engine lift
brackets and lift cylinder head off engine and out of
vehicle.
(36) Remove the head gasket and inspect for fail-
ure.
CLEANINGÐCYLINDER HEAD
CAUTION: Do not wire brush head surface while
fuel injectors are still installed. Fuel injector dam-
age can result.
Clean the carbon from the injector nozzle seat with
a nylon or brass brush.
Scrape the gasket residue from all gasket surfaces.
Wash the cylinder head in hot soapy water solution
(88ÉC or 140ÉF).
Fig. 19 High-Pressure Lines at Fuel Injection Pump
1 - HIGH-PRESSURE LINES AT INJECTION PUMP
2 - FITTINGS
3 - FUEL INJECTION PUMP
Fig. 20 IAT and MAP Sensor Location
1 - MANIFOLD AIR PRESSURE (MAP) SENSOR
2 - REAR OF CYLINDER HEAD
3 - IAT SENSOR
4 - ELECTRICAL CONNECTOR
5 - ELECTRICAL CONNECTOR
9 - 248 ENGINE 5.9L DIESELBR/BE
CYLINDER HEAD (Continued)

FUEL INJECTION - GASOLINE
TABLE OF CONTENTS
page page
FUEL INJECTION - GASOLINE
DIAGNOSIS AND TESTING.................28
VISUAL INSPECTION - 3.9L/5.2L/5.9L
ENGINES.............................28
VISUAL INSPECTION - 8.0L ENGINE........32
SPECIFICATIONS........................35
SPECIAL TOOLS.........................36
ACCELERATOR PEDAL
REMOVAL..............................37
INSTALLATION...........................37
CRANKSHAFT POSITION SENSOR
DESCRIPTION...........................38
OPERATION.............................38
REMOVAL..............................39
INSTALLATION...........................40
FUEL PUMP RELAY
DESCRIPTION...........................41
OPERATION.............................41
REMOVAL..............................41
INSTALLATION...........................41
IDLE AIR CONTROL MOTOR
DESCRIPTION...........................41
OPERATION.............................41
REMOVAL..............................42
INSTALLATION...........................42
INTAKE AIR TEMPERATURE SENSOR
DESCRIPTION...........................43
OPERATION.............................43
REMOVAL..............................43
INSTALLATION...........................43
MANIFOLD ABSOLUTE PRESSURE SENSOR
DESCRIPTION...........................44OPERATION.............................44
REMOVAL..............................45
INSTALLATION...........................45
O2 SENSOR
DESCRIPTION...........................46
OPERATION.............................46
REMOVAL..............................47
INSTALLATION...........................48
PTO SWITCH
DESCRIPTION...........................48
OPERATION.............................48
THROTTLE BODY
DESCRIPTION...........................48
OPERATION.............................48
REMOVAL..............................48
INSTALLATION...........................49
THROTTLE CONTROL CABLE
REMOVAL..............................50
INSTALLATION...........................50
THROTTLE POSITION SENSOR
DESCRIPTION...........................51
OPERATION.............................51
REMOVAL..............................51
INSTALLATION...........................52
FUEL INJECTOR
DESCRIPTION...........................53
OPERATION.............................53
DIAGNOSIS AND TESTING.................53
FUEL INJECTOR TEST...................53
REMOVAL..............................53
INSTALLATION...........................53
FUEL INJECTION - GASOLINE
VISUAL INSPECTIONÐ3.9L/5.2L/5.9L
ENGINES
A visual inspection for loose, disconnected or incor-
rectly routed wires and hoses should be made. This
should be done before attempting to diagnose or ser-
vice the fuel injection system. A visual check will
help spot these faults and save unnecessary test and
diagnostic time. A thorough visual inspection will
include the following checks:
(1) Verify that the three 32±way electrical connec-
tors are fully inserted into the connector of the pow-
ertrain control module (PCM) (Fig. 1).(2) Inspect the battery cable connections. Be sure
that they are clean and tight.
(3) Inspect fuel pump relay and air conditioning
compressor clutch relay (if equipped). Inspect the
ASD relay connections. Inspect starter motor relay
connections. Inspect relays for signs of physical dam-
age and corrosion. The relays are located in the
Power Distribution Center (PDC) (Fig. 2). Refer to
label on PDC cover for relay location.
(4) Inspect ignition coil connections. Verify that
coil secondary cable is firmly connected to coil (Fig.
3).
14 - 28 FUEL INJECTION - GASOLINEBR/BE

(11) Inspect accelerator cable, transmission throt-
tle cable (if equipped) and cruise control cable con-
nections (if equipped). Check their connections to the
throttle arm of throttle body for any binding or
restrictions.
(12) If equipped with vacuum brake booster, verify
that vacuum booster hose is firmly connected to fit-
ting on intake manifold. Also check connection to
brake vacuum booster.
(13) Inspect the air cleaner inlet and air cleaner
element for dirt or restrictions.
(14) Inspect radiator grille area, radiator fins and
air conditioning condenser for restrictions.
(15) Verify that the intake manifold air tempera-
ture sensor wire connector is firmly connected to har-
ness connector (Fig. 5).
(16) Verify that MAP sensor electrical connector is
firmly connected to MAP sensor (Fig. 6). Also verify
that rubber L-shaped fitting from MAP sensor to the
throttle body is firmly connected (Fig. 7).
(17) Verify that fuel injector wire harness connec-
tors are firmly connected to injectors in the correct
order. Each harness connector is numerically tagged
with the injector number (INJ 1, INJ 2 etc.) of its
corresponding fuel injector and cylinder number.
(18) Verify harness connectors are firmly con-
nected to idle air control (IAC) motor, throttle posi-
tion sensor (TPS) and manifold absolute pressure
(MAP) sensor (Fig. 6).
(19) Verify that wire harness connector is firmly
connected to the engine coolant temperature sensor
(Fig. 8).
(20) Raise and support the vehicle.(21) Verify oxygen sensor wire connectors are
firmly connected to the sensors. Inspect sensors and
connectors for damage (Fig. 9), (Fig. 10) or (Fig. 11).
(22) Inspect for pinched or leaking fuel tubes.
Inspect for pinched, cracked or leaking fuel hoses.
Fig. 5 Air Temperature
1 - INTAKE MANIFOLD AIR TEMPERATURE SENSOR
2 - ELECTRICAL CONNECTOR
Fig. 6 Sensor and IAC Motor LocationÐTypical (V-8
Shown)
1 - MAP SENSOR
2 - IDLE AIR CONTROL MOTOR
3 - THROTTLE POSITION SENSOR
Fig. 7 Rubber L-Shaped FittingÐMAP Sensor-to-
Throttle BodyÐ3.9L/5.2L/5.9L Engines
1 - MAP SENSOR
2 - RUBBER FITTING
3 - IDLE AIR PASSAGE
14 - 30 FUEL INJECTION - GASOLINEBR/BE
FUEL INJECTION - GASOLINE (Continued)

(5) Install new plastic tie strap (Fig. 28) to secure
sensor pigtail harness to side of engine block. Thread
tie strap through casting hole on cylinder block.
FUEL PUMP RELAY
DESCRIPTION
The 5±pin, 12±volt, fuel pump relay is located in
the Power Distribution Center (PDC). Refer to the
label on the PDC cover for relay location.
OPERATION
The Powertrain Control Module (PCM) energizes
the electric fuel pump through the fuel pump relay.
The fuel pump relay is energized by first applying
battery voltage to it when the ignition key is turned
ON, and then applying a ground signal to the relay
from the PCM.
Whenever the ignition key is turned ON, the elec-
tric fuel pump will operate. But, the PCM will shut-
down the ground circuit to the fuel pump relay in
approximately 1±3 seconds unless the engine is oper-
ating or the starter motor is engaged.
REMOVAL
The fuel pump relay is located in the Power Distri-
bution Center (PDC) (Fig. 31). Refer to label on PDC
cover for relay location.
(1) Remove PDC cover.
(2) Remove relay from PDC.
(3) Check condition of relay terminals and PDC
connector terminals for damage or corrosion. Repair
if necessary before installing relay.
(4) Check for pin height (pin height should be the
same for all terminals within the PDC connector).
Repair if necessary before installing relay.
INSTALLATION
The fuel pump relay is located in the Power Distri-
bution Center (PDC) (Fig. 31). Refer to label on PDC
cover for relay location.
(1) Install relay to PDC.
(2) Install cover to PDC.
IDLE AIR CONTROL MOTOR
DESCRIPTION
The IAC stepper motor is mounted to the throttle
body, and regulates the amount of air bypassing the
control of the throttle plate. As engine loads and
ambient temperatures change, engine rpm changes.
A pintle on the IAC stepper motor protrudes into a
passage in the throttle body, controlling air flow
through the passage. The IAC is controlled by the
Powertrain Control Module (PCM) to maintain the
target engine idle speed.
OPERATION
At idle, engine speed can be increased by retract-
ing the IAC motor pintle and allowing more air to
pass through the port, or it can be decreased by
restricting the passage with the pintle and diminish-
ing the amount of air bypassing the throttle plate.
The IAC is called a stepper motor because it is
moved (rotated) in steps, or increments. Opening the
IAC opens an air passage around the throttle blade
which increases RPM.
The PCM uses the IAC motor to control idle speed
(along with timing) and to reach a desired MAP dur-
ing decel (keep engine from stalling).
The IAC motor has 4 wires with 4 circuits. Two of
the wires are for 12 volts and ground to supply electri-
cal current to the motor windings to operate the step-
per motor in one direction. The other 2 wires are also
for 12 volts and ground to supply electrical current to
operate the stepper motor in the opposite direction.
To make the IAC go in the opposite direction, the
PCM just reverses polarity on both windings. If only
1 wire is open, the IAC can only be moved 1 step
(increment) in either direction. To keep the IAC
motor in position when no movement is needed, the
PCM will energize both windings at the same time.
This locks the IAC motor in place.
In the IAC motor system, the PCM will count
every step that the motor is moved. This allows the
PCM to determine the motor pintle position. If the
memory is cleared, the PCM no longer knows the
position of the pintle. So at the first key ON, the
PCM drives the IAC motor closed, regardless of
where it was before. This zeros the counter. From
this point the PCM will back out the IAC motor and
keep track of its position again.
Fig. 31 Power Distribution Center (PDC)
1 - POWER DISTRIBUTION CENTER (PDC)
BR/BEFUEL INJECTION - GASOLINE 14 - 41
CRANKSHAFT POSITION SENSOR (Continued)