2002 DODGE RAM engine

FUEL TEMPERATURE SENSOR
DESCRIPTION
Two different fuel temperature sensors are used.
One of the sensors is located inside of the Bosch
VP44 fuel injection pump and is a non-serviceable
part. The other fuel temperature sensor is located in
the top of the fuel filter housing and is serviceable
(serviceable if replacing the fuel heater).
OPERATION
The sensor located in the Bosch VP44 fuel injection
pump is used to check fuel temperature within the
injection pump and to set a Diagnostic Trouble Code
(DTC) if a specific high fuel temperature has been
reached. If high temperature has been reached,
engine power will be de-rated by the Engine Control
Module (ECM).
The sensor located in the top of the fuel filter hous-
ing is used to control the fuel heater element. Refer
to Fuel Heater Description and Operation for addi-
tional information.
INTAKE AIR HEATER
DESCRIPTION
The intake manifold air heater element assembly
is located in the top of the intake manifold (Fig. 25).
OPERATION
The air heater elements are used to heat incoming
air to the intake manifold. This is done to help
engine starting and improve driveability with cool or
cold outside temperatures.
Electrical supply for the 2 air heater elements is
controlled by the Engine Control Module (ECM)
through the 2 air heater relays. Refer to Intake Man-
ifold Air Heater Relays for more information.
Two heavy-duty cables connect the 2 air heater ele-
ments to the 2 air heater relays. Each of these cables
will supply approximately 95 amps at 12 volts to an
individual heating element within the heater block
assembly.
Refer to the Powertrain Diagnostic Procedures
manual for an electrical operation and complete
description of the intake heaters, including pre-heat
and post-heat cycles.
REMOVAL
The 2 intake manifold air heater elements are
attached to a metal block located at the top of the
intake manifold (Fig. 26). If servicing either of the
heater elements, the entire block/element assembly
must be replaced.
(1) Disconnect both negative battery cables at both
batteries.
(2) Disconnect clamp from rubber hose at air
intake housing.
(3) Disconnect rubber hose at air intake housing.
Fig. 25 Air Heater Elements Location
1 - AIR HEATER ELEMENTS
2 - LOWER GASKET
3 - BLOCK
4 - UPPER GASKET
Fig. 26 Intake Manifold Air Heater Element Location
1 - AIR HEATER ELEMENTS
2 - LOWER GASKET
3 - BLOCK
4 - UPPER GASKET
14 - 104 FUEL INJECTION - DIESELBR/BE

(4) Remove engine oil dipstick tube mounting bolt
(Fig. 28). Position dipstick tube to the side.(5) Disconnect heater electrical cables at cable
mounting studs (Fig. 28).
(6) Disconnect ground cable bolt and ground cable
from housing (Fig. 27).
(7) Remove 4 housing bolts (Fig. 28).
(8) Remove air intake housing from top of heater
elements.
(9) Remove heater element assembly from intake
manifold.
(10) Clean old gasket material from air intake
housing and intake manifold.
(11) Clean old gasket material from both ends of
heater block (Fig. 26).
INSTALLATION
The 2 intake manifold air heater elements are
attached to a metal block located at the top of the
intake manifold (Fig. 26). If servicing either of the
heater elements, the entire block/element assembly
must be replaced.
(1) Using 2 new gaskets, position element assem-
bly and air housing to intake manifold.
(2) Position ground cable (Fig. 27) to air housing.
(3) Install 4 housing bolts and tighten to 24 N´m
(18 ft. lbs.) torque.
(4) Connect heater cables at cable mounting studs
(Fig. 28).Do not allow the cable eyelets to con-
tact any other metal source other than the
cable nuts/studs.
(5) Install engine oil dipstick tube and mounting
bolt.
(6) Connect rubber hose to air intake housing.
(7) Connect clamp to rubber hose at air intake
housing.
(8) Connect both negative battery cables at both
batteries.
INTAKE AIR HEATER RELAY
DESCRIPTION
The 2 intake manifold air heater relays are located
in the engine compartment, attached to the left inner
fender below the left battery (Fig. 29).
OPERATION
The Engine Control Module (ECM) operates the 2
heating elements through the 2 intake manifold air
heater relays.
Refer to Powertrain Diagnostic Procedures for an
electrical operation and complete description of the
intake heaters, including pre-heat and post-heat
cycles.
Fig. 27 Air Intake Housing (Front View)
1 - GROUND CABLE BOLT
2 - INTAKE AIR HOUSING
3 - CABLE BRACKET HOUSING BOLTS (3)
4 - GROUND CABLE
Fig. 28 Air Intake Housing (Rear View)
1 - TUBE MOUNTING BOLT
2 - HOUSING BOLTS (2)
3 - INTAKE HEATER CABLE MOUNTING STUDS (2)
4 - DIPSTICK TUBE
BR/BEFUEL INJECTION - DIESEL 14 - 105
INTAKE AIR HEATER (Continued)

REMOVAL
The relays are located in engine compartment,
bolted to left inner fender below left battery (Fig. 30).
The mounting bracket and both relays are replaced
as an assembly.
(1) Disconnect both negative battery cables at both
batteries.
(2) Disconnect four relay trigger wires at both
relays (Fig. 30). Note position of wiring before remov-
ing.
(3) Lift four rubber shields from all 4 cables (Fig.
30).
(4) Remove four nuts at cable connectors (Fig. 30).
Note position of wiring before removing.
(5) Remove three relay mounting bracket bolts
(Fig. 30) and remove relay assembly.
INSTALLATION
The relays are located in engine compartment,
bolted to left inner fender below left battery (Fig. 30).
(1) Install relay assembly to inner fender. Tighten
mounting bolts to 4.5 N´m (40 in. lbs.) torque.
(2) Connect eight electrical connectors to relays.
(3) Connect battery cables to both batteries.
INTAKE AIR TEMPERATURE
SENSOR
DESCRIPTION - DIESEL
The intake manifold air temperature sensor is
installed into the rear of the intake manifold (Fig.
31) with the sensor element extending into the air
stream.
OPERATION - DIESEL
The IAT provides an input voltage to the Engine
Control Module (ECM) indicating intake manifold air
temperature. The input is used along with inputs
from other sensors for intake air heater element
operation, for engine protection, fuel timing and fuel
control. As the temperature of the air-fuel stream in
the manifold varies, the sensor resistance changes.
This results in a different input voltage to the ECM.
Fig. 29 Intake Manifold Air Heater Relays Location
1 - BATTERY (LEFT SIDE)
2 - RELAY MOUNTING BOLTS (3)
3 - RELAY TRIGGER WIRES (4)
4 - INTAKE AIR HEATER RELAYS (2)
5 - RUBBER SHIELDS (4)
6 - CABLES TO BATTERY (+)
Fig. 30 Intake Manifold Air Heater Relays
1 - BATTERY (LEFT SIDE)
2 - RELAY MOUNTING BOLTS (3)
3 - RELAY TRIGGER WIRES (4)
4 - INTAKE AIR HEATER RELAYS (2)
5 - RUBBER SHIELDS (4)
6 - CABLES TO BATTERY (+)
14 - 106 FUEL INJECTION - DIESELBR/BE
INTAKE AIR HEATER RELAY (Continued)

REMOVAL - DIESEL
The IAT sensor is located in the left/rear side of
the intake manifold (Fig. 32).
The IAT sensor is located in the left/rear side of
the intake manifold (Fig. 32).
(1) Disconnect electrical connector from IAT sensor
(Fig. 32).
(2) Remove IAT sensor from intake manifold (Fig.
33).
(3) Discard sensor o-ring (Fig. 33).
INSTALLATION - DIESEL
The IAT sensor is located in the left/rear side of
the intake manifold (Fig. 32).
(1) Clean sensor mounting hole (Fig. 33) of rust or
contaminants.
(2) Install new o-ring to sensor. Apply clean engine
oil to sensor o-ring and sensor threads.
(3) Install IAT sensor into intake manifold.
Tighten to 14 N´m (10 ft. lbs.) torque.
(4) Connect sensor electrical connector.
Fig. 31 Intake Manifold Air Temperature (IAT) Sensor
Location
1 - MANIFOLD AIR PRESSURE (MAP) SENSOR
2 - REAR OF CYLINDER HEAD
3 - IAT SENSOR
4 - ELECTRICAL CONNECTOR
5 - ELECTRICAL CONNECTOR
Fig. 32 IAT Sensor
1 - SENSOR MOUNTING HOLES
2 - O-RING
3 - IAT SENSOR
4 - MAP SENSOR
5 - O-RING
Fig. 33 Intake Manifold Air Temperature (IAT) Sensor
Location
1 - MANIFOLD AIR PRESSURE (MAP) SENSOR
2 - REAR OF CYLINDER HEAD
3 - IAT SENSOR
4 - ELECTRICAL CONNECTOR
5 - ELECTRICAL CONNECTOR
BR/BEFUEL INJECTION - DIESEL 14 - 107
INTAKE AIR TEMPERATURE SENSOR (Continued)

MAP SENSOR
DESCRIPTION - DIESEL
The MAP sensor is installed into the rear of the
intake manifold (Fig. 31).
OPERATION - DIESEL
The MAP sensor reacts to air pressure changes in
the intake manifold. It provides an input voltage to
the Engine Control Module (ECM). As pressure
changes, MAP sensor voltage will change. The
change in MAP sensor voltage results in a different
input voltage to the ECM. The ECM uses this input,
along with inputs from other sensors to provide fuel
timing, fuel control and engine protection. Engine
protection is used to derate (drop power off) the
engine if turbocharger pressure becomes to high.
REMOVAL - DIESEL
The MAP sensor is located in the left/rear side of
the intake manifold (Fig. 34).
The MAP sensor is located in the left/rear side of
the intake manifold (Fig. 34).
(1) Disconnect electrical connector from MAP sen-
sor (Fig. 34).
(2) Remove MAP sensor from intake manifold (Fig.
35).
(3) Discard sensor o-ring (Fig. 35).
INSTALLATION
The MAP sensor is located in the left/rear side of
the intake manifold (Fig. 34).
(1) Clean sensor mounting hole (Fig. 35) of rust or
contaminants.
(2) Install new o-ring to sensor. Apply clean engine
oil to sensor o-ring and sensor threads.
(3) Install MAP sensor into intake manifold.
Tighten to 14 N´m (10 ft. lbs.) torque.
(4) Connect sensor electrical connector.
PTO SWITCH
DESCRIPTION
OPERATION
This Engine Control Module (ECM) input is used
only on models equipped with aftermarket Power
Take Off (PTO) units.
The input is used to tell the ECM that the PTO
has been engaged. When engaged, the ECM will dis-
able certain OBD II functions until the PTO has been
turned off.
Fig. 34 MAP Sensor Location
1 - MANIFOLD AIR PRESSURE (MAP) SENSOR
2 - REAR OF CYLINDER HEAD
3 - IAT SENSOR
4 - ELECTRICAL CONNECTOR
5 - ELECTRICAL CONNECTOR
Fig. 35 MAP Sensor Removal/Installation
1 - SENSOR MOUNTING HOLES
2 - O-RING
3 - IAT SENSOR
4 - MAP SENSOR
5 - O-RING
14 - 108 FUEL INJECTION - DIESELBR/BE

THROTTLE CONTROL CABLE
REMOVAL
(1) Disconnect both negative battery cables at both
batteries.
(2) From inside vehicle, hold up accelerator pedal.
Remove plastic cable retainer and throttle cable core
wire from upper end of pedal arm (Fig. 39). The plas-
tic cable retainer snaps into pedal arm.
(3) Remove cable core wire at pedal arm.
(4) From inside vehicle, pinch both sides of plastic
cable housing retainer tabs at dash panel.
(5) Remove cable housing from dash panel and
pull cable into engine compartment.
(6) Remove cable cover (Fig. 36). Cable cover is
attached with 2 Phillips screws, 2 plastic retention
clips and 2 push tabs (Fig. 36). Remove 2 Phillips
screws and carefully pry out 2 retention clips. After
clip removal, push rearward on front tab, and
upward on lower tab for cover removal.
(7) Using 2 screwdrivers, pry cable connector
socket from throttle lever ball (Fig. 37).Be very
careful not to bend throttle lever arm.
(8) Squeeze 2 pinch tabs on sides of throttle cable
at mounting bracket (Fig. 38) and push cable rear-
ward out of bracket.
Fig. 36 Cable/Lever/Throttle Linkage Cover
1 - CABLE/LEVER/LINKAGE COVER
2 - PUSH UP LOWER TAB
3 - SCREWS/CLIPS (2)
4 - TAB PUSH HERE
Fig. 37 Throttle Cable at Throttle Lever
1 - PINCH (2) TABS
2 - CABLE MOUNTING BRACKET
3 - PINCH TABS (2)
4 - OFF
5 - THROTTLE CABLE
6 - THROTTLE LEVER
7 - THROTTLE LEVER PIN
8 - OFF
9 - CONNECTOR
10 - SPEED CONTROL CABLE
Fig. 38 Cable Release
1-TAB
BR/BEFUEL INJECTION - DIESEL 14 - 109

INSTALLATION
(1) Install cable through mounting hole on cable
mounting bracket (Fig. 37). Cable snaps into bracket.
Be sure 2 pinch tabs are secure.
(2) Using large pliers, connect cable end socket to
throttle lever ball (snaps on).
(3) Install remaining cable housing end into and
through dash panel opening (snaps into position).
The two plastic pinch tabs should lock cable to dash
panel.
(4) From inside vehicle, hold up accelerator pedal.
Install throttle cable core wire and plastic cable
retainer into and through upper end of pedal arm
(the plastic retainer is snapped into pedal arm).
When installing plastic retainer to accelerator pedal
arm, note index tab on pedal arm (Fig. 39). Align
index slot on plastic cable retainer to this index tab.
(5) Connect negative battery cables to both batter-
ies.
(6) Before starting engine, operate accelerator
pedal to check for any binding.
(7) Install cable/lever cover.
Fig. 39 Cable Removal/Installation at Pedal
1 - PINCH TWO TABS FOR CABLE REMOVAL
2 - DASH PANEL
3 - CABLE CORE WIRE
4 - THROTTLE PEDAL ARM
5 - INDEX TAB
6 - CABLE RETAINER
7 - CABLE STOP
14 - 110 FUEL INJECTION - DIESELBR/BE
THROTTLE CONTROL CABLE (Continued)

LOOSE STEERING AND VEHICLE LEAD
CONDITION POSSIBLE CAUSE CORRECTION
EXCESSIVE PLAY IN STEERING
WHEEL1. Worn or loose suspension or
steering components.1. Inspect and repair as necessary.
2. Worn or loose wheel bearings. 2. Inspect and repair or adjust
bearings.
3. Steering gear mounting. 3. Tighten gear mounting bolts to
specification.
4. Gear out of adjustment. 4. Adjust gear to specification.
5. Worn or loose steering coupler. 5. Inspect and replace as
necessary.
VEHICLE PULLS OR LEADS TO
ONE SIDE.1. Tire Pressure. 1. Adjust tire pressure.
2. Radial tire lead. 2. Rotate tires.
3. Brakes dragging. 3. Repair as necessary.
4. Wheel alignment. 4. Align front end.
DIAGNOSIS AND TESTING - POWER STEERING
FLOW AND PRESSURE
The following procedure is used to test the opera-
tion of the power steering system on the vehicle. This
test will provide the flow rate of the power steering
pump along with the maximum relief pressure. Per-
form test any time a power steering system problem
is present. This test will determine if the power
steering pump or power steering gear is not function-
ing properly. The following pressure and flow test is
performed using Power Steering Analyzer Tool kit
6815 (Fig. 2) and Adapter Kit 6893.
POWER STEERING ANALYZER INSTALLATION
WITHOUT HYDRAULIC BOOSTER
(1) Remove the high pressure hose from the power
steering pump.
(2) Connect Tube 6844 into the pump hose fitting.
(3) Connect pressure gauge hose from the Power
Steering Analyzer to Tube 6844.
(4) Connect Adapter 6826 to Power Steering Ana-
lyzer test valve end.
(5) Connect the power steering hose from the
steering gear to Adapter 6826.
WITH HYDRAULIC BOOSTER
(1) Remove high pressure hose which goes to the
steering gear from the tube coming out of the booster.
(2) Connect Adapter 6826 to the Power Steering
Analyzer pressure gauge hose.
(3) Connect pressure gauge hose to the tube com-
ing out of the booster.
(4) Connect Tube 6844 to the steering gear hose
and Power Steering Analyzer test valve end.
FLOW AND PRESSURE TEST
(1) Check belt condition and tension.
(2) Open the test valve completely.
(3) Start engine and let idle long enough to circu-
late power steering fluid through flow/pressure test
gauge and to get air out of the fluid. Then shut off
engine.
(4) Check fluid level, add fluid as necessary. Start
engine again and let idle.
(5) Gauge should read below 1034 kPa (150 psi), if
above, inspect the hoses for restrictions and repair as
Fig. 2 Pressure Test Gauge
1 - GAUGE HOSE
2 - TUBE
3 - ADAPTER FITTINGS
4 - ANALYZER
19 - 4 STEERINGBR/BE
STEERING (Continued)