1998 DODGE RAM 1500 clock

(3) Gently lift on small plastic release tab (Fig. 17)
or (Fig. 18) and rotate sensor about 1/4 turn counter-
clockwise for removal.
(4) Check condition of sensor o-ring.
5.7L V-8
The intake manifold air temperature (IAT) sensor
is installed into the front of the intake manifold air
box plenum (Fig. 19).
(1) Disconnect electrical connector from IAT sensor
(Fig. 19).
(2) Clean dirt from intake manifold at sensor base.
(3) Gently lift on small plastic release tab (Fig. 17)
or (Fig. 20) and rotate sensor about 1/4 turn counter-
clockwise for removal.
(4) Check condition of sensor o-ring.
INSTALLATION
3.7L V-6
The intake manifold air temperature (IAT) sensor
is installed into the left side of intake manifold ple-
num (Fig. 16).
(1) Check condition of sensor o-ring.
(2) Clean sensor mounting hole in intake manifold.
(3) Position sensor into intake manifold and rotate
clockwise until past release tab (Fig. 16).
(4) Install electrical connector.
4.7L V-8
The intake manifold air temperature (IAT) sensor
is installed into the left side of intake manifold ple-
num (Fig. 18).
(1) Check condition of sensor o-ring.
(2) Clean sensor mounting hole in intake manifold.
Fig. 17 IAT SENSOR TAB / O-RING - 3.7L V-6/4.7L
V-8/5.7L V-8
1 - IAT SENSOR
2 - SENSOR O-RING
3 - RELEASE TAB
Fig. 18 IAT SENSOR - 4.7L V-8
1 - LEFT SIDE OF THROTTLE BODY
2 - ELEC. CONNECT.
3 - IAT SENSOR
4 - RELEASE TAB
Fig. 19 5.7L IAT SENSOR LOCATION
1 - FRONT OF INTAKE MANIFOLD PLENUM
2 - IAT ELECTRICAL CONNECTOR
DRFUEL INJECTION - GAS 14 - 31
INTAKE AIR TEMPERATURE SENSOR (Continued)

(3) Position sensor into intake manifold and rotate
clockwise until past release tab.
(4) Install electrical connector.
5.7L V-8
The intake manifold air temperature (IAT) sensor
is installed into the front of the intake manifold air
box plenum (Fig. 19).
(1) Check condition of sensor o-ring.
(2) Clean sensor mounting hole in intake manifold.
(3) Position sensor into intake manifold and rotate
clockwise until past release tab.
(4) Install electrical connector.
MAP SENSOR
DESCRIPTION
3.7L V-6
The Manifold Absolute Pressure (MAP) sensor is
mounted into the front of the intake manifold with 2
screws.
4.7L V-8
The Manifold Absolute Pressure (MAP) sensor is
mounted into the front of the intake manifold with 2
screws.
5.7L V-8
The Manifold Absolute Pressure (MAP) sensor is
mounted to the front of the intake manifold air ple-
num box.
OPERATION
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 voltage
again, 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
Fig. 20 5.7L IAT SENSOR R/I
1 - FRONT OF INTAKE MANIFOLD PLENUM
2 - IAT SENSOR
3 - RELEASE TAB
14 - 32 FUEL INJECTION - GASDR
INTAKE AIR TEMPERATURE SENSOR (Continued)

5.7L V-8
The Manifold Absolute Pressure (MAP) sensor is
mounted to the front of the intake manifold air ple-
num box (Fig. 24).
(1) Disconnect electrical connector at sensor by
sliding release lock out (Fig. 25). Press down on lock
tab for removal.
(2) Rotate sensor 1/4 turn counter-clockwise for
removal.
(3) Check condition of sensor o-ring.
INSTALLATION
3.7L V-6
The Manifold Absolute Pressure (MAP) sensor is
mounted into the front of the intake manifold (Fig.
21). An o-ring is used to seal the sensor to the intake
manifold (Fig. 22).
(1) Clean MAP sensor mounting hole at intake
manifold.
(2) Check MAP sensor o-ring seal for cuts or tears.
(3) Position sensor into manifold.
(4) Install MAP sensor mounting bolts (screws).
Refer to Torque Specifications.
(5) Connect electrical connector.
4.7L V-8
The MAP sensor is located on the front of the
intake manifold (Fig. 23). An o-ring seals the sensor
to the intake manifold (Fig. 22).(1) Clean MAP sensor mounting hole at intake
manifold.
(2) Check MAP sensor o-ring seal for cuts or tears.
(3) Position sensor into manifold.
Fig. 23 MAP SENSOR - 4.7L V-8
1 - ECT SENSOR
2 - MOUNTING BOLTS (2)
3 - MAP SENSOR
4 - INTAKE MANIFOLDFig. 24 5.7L MAP SENSOR LOCATION
1 - MAP SENSOR
2 - FRONT OF INTAKE MANIFOLD
Fig. 25 5.7L MAP SENSOR R/I
1 - PRESS DOWN
2 - SLIDE RELEASE LOCK
3 - MAP SENSOR
14 - 34 FUEL INJECTION - GASDR
MAP SENSOR (Continued)

(4) Install MAP sensor mounting bolts (screws).
Refer to Torque Specifications.
(5) Connect electrical connector.
5.7L V-8
The Manifold Absolute Pressure (MAP) sensor is
mounted to the front of the intake manifold air ple-
num box (Fig. 24).
(1) Clean MAP sensor mounting hole at intake
manifold.
(2) Check MAP sensor o-ring seal for cuts or tears.
(3) Position sensor into manifold.
(4) Rotate sensor 1/4 turn clockwise for installa-
tion.
(5) Connect electrical connector.
OXYGEN SENSOR
DESCRIPTION
The Oxygen Sensors (O2S) are attached to, and
protrude into the vehicle exhaust system. Depending
on the engine or emission package, the vehicle may
use a total of either 2 or 4 sensors.
Federal Emission Packages :Two sensors are
used: upstream (referred to as 1/1) and downstream
(referred to as 1/2). With this emission package, the
upstream sensor (1/1) is located just before the main
catalytic convertor. The downstream sensor (1/2) is
located just after the main catalytic convertor.
California Emission Packages:On this emis-
sions package, 4 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 pack-
age, 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-cata-
lytic convertor. The right downstream sensor (2/2) is
located in the right exhaust downpipe just after the
mini-catalytic convertor, and before the main cata-
lytic convertor. The left downstream sensor (1/2) is
located in the left exhaust downpipe just after the
mini-catalytic convertor, and before the main cata-
lytic convertor.
REMOVAL
CAUTION: Never apply any type of grease to the
oxygen sensor electrical connector, or attempt any
soldering of the sensor wiring harness.
Refer to (Fig. 26) or (Fig. 27) for typical O2S (oxy-
gen sensor) locations.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 vehicle.
(2) Disconnect wire connector from O2S sensor.
CAUTION: When disconnecting sensor electrical
connector, do not pull directly on wire going into
sensor.
(3) Remove O2S sensor with an oxygen sensor
removal and installation tool.
(4) Clean threads in exhaust pipe using appropri-
ate tap.
Fig. 26 O2 SENSOR SYSTEM - WITH 4 SENSORS
Fig. 27 O2 SENSOR SYSTEM - WITH 2 SENSORS
1 - POST CATALYST OXYGEN SENSOR (1/3)
2 - PRE-CATALYST OXYGEN SENSOR (1/2)
DRFUEL INJECTION - GAS 14 - 35
MAP SENSOR (Continued)

FUEL FILTER / WATER
SEPARATOR
DESCRIPTION
The fuel filter/water separator assembly is located
on left side of engine above the starter motor. The
assembly also includes the fuel heater, Water-In-Fuel
(WIF) sensor, and fuel transfer pump.
OPERATION
The fuel filter/water separator protects the fuel
injection pump by removing water and contaminants
from the fuel. The construction of the filter/separator
allows fuel to pass through it, but helps prevent
moisture (water) from doing so. Moisture collects at
the bottom of the canister.
Refer to the maintenance schedules in the owners
manual for the recommended fuel filter replacement
intervals.
For draining of water from canister, refer to Fuel
Filter/Water Separator Removal/Installation section.
A Water-In-Fuel (WIF) sensor is attached to the
side of fuel filter housing. Refer to Water-In-Fuel
Sensor Description/Operation.
The fuel heater is installed into the top of the fil-
ter/separator housing. Refer to Fuel Heater Descrip-
tion/Operation.
REMOVAL
Refer to maintenance schedules in this manual, or
the owners manual for recommended fuel filter
replacement intervals.
Draining water from fuel filter/water separa-
tor housing:
The housing drain valve (Fig. 3) serves two pur-
poses. One is topartiallythe drain filter housing of
excess water. The other is tocompletelythe drain
housing for fuel filter, drain valve, heater element, ,
water-in-fuel sensor replacement or transfer pump
replacement.
The filter housing should be partially drained
whenever the water-in-fuel warning lamp remains
illuminated. (Note that lamp will be illuminated for
approximately two seconds when ignition key is ini-
tially placed in ON position for a bulb check).(1) A drain hose (Fig. 3) is located at the bottom of
drain valve. Place drain pan under drain hose.
(2)With engine not running,rotate drain valve
handle counter-clockwise (rearward) to OPEN
(DRAIN) position. Hold drain valve open until all
water and contaminants have been removed and
clean fuel exits.
(3) If drain valve, fuel heater element or Water-In-
Fuel (WIF) sensor is being replaced, drain housing
completely. Dispose of mixture in drain pan according
to applicable regulations.
(4) After draining operation, rotate valve handle
clockwise (forward) to the CLOSE position.
(5)Fuel Filter Replacement:The fuel filter is
located inside of the fuel filter housing.
(a) Clean all debris from around canister.
(b) Remove filter lid (Fig. 4) using a socket.
Attach socket to large hex on top of lid (Fig. 4).
Rotate counter-clockwise for removal. Remove
o-ring. Discard o-ring.
(c) Remove filter element by twisting element
sideways from filter lid.
(6)Water-In-Fuel (WIF) Sensor Replacement:
The WIF sensor is located on the side of the fuel fil-
ter housing (Fig. 3).
(a) Disconnect electrical connector at sensor.
(b) Clean area around sensor.
(c) Remove sensor by rotating counter-clockwise.
(d) Check condition of sensor o-ring. Replace if
damaged.
(7)Fuel Heater Element Replacement:The
heater element is located in the fuel filter housing
(Fig. 3).
(a) Remove fuel filter. See previous steps.
(b) Disconnect electrical connector.
(c) Remove two T-15 Torx head mounting screws
from fuel heater element.
(d) Remove fuel heater.
(8)Drain Valve Replacement:The drain valve
assembly is located on the side of the fuel filter hous-
ing (Fig. 3).
(a) Disconnect drain hose from the fuel drain
valve.
(b) Remove 4 drain valve mounting screws (T-15
Torx head).
(c) Remove drain valve from filter housing.
INSTALLATION
Refer to maintenance schedules for recommended
fuel filter replacement intervals.
(1) Thoroughly clean inside of filter housing, filter
cap and all related components.
(2)Fuel Filter:
(a)The engine has a self-priming low-pres-
sure fuel system. Refer to Standard Proce-
dures-Fuel System Priming.
ENGINE ROTATING (BARRING) TOOL - #7471B
(ALSO PART OF KIT #6860)
14 - 50 FUEL DELIVERY - DIESELDR
FUEL DELIVERY - DIESEL (Continued)

(b) Install new o-ring to canister lid and lubri-
cate o-ring with clean engine oil.
(c) Position new element to canister lid. Place
this assembly into canister by rotating clockwise.
(d) Tighten cap to 34 N´m (25 ft. lbs.) torque. Do
not overtighten cap.
(3)Water-In-Fuel (WIF) Sensor:
(a) Install new o-ring seal to WIF sensor.
(b) Apply a light film of clean oil to o-ring seal.
(c) Install sensor into housing.
(d) Tighten sensor to 2.5 N´m (25 in. lbs.) torque.
(e) Connect electrical connector to WIF sensor.
(4)Fuel Heater Element:
(a) Install fuel heater into fuel filter housing.
(b) Install fuel heater thermostat into fuel filter
housing.
(c) Install fuel heater mounting screws and
tighten to 1-1.5 N´m (13 in. lbs.) torque.
(d) Connect electrical connector to fuel heater
thermostat.
(e) Install new filter cover O-ring onto fuel filter
housing cover and lubricate with clean engine oil.
(f) Tighten fuel filter housing cover (lid) to 34
N´m (25 ft. lbs.).
(5)Drain Valve:
(a) Install 2 new o-rings to valve and filter hous-
ing.
(b) Lubricate with silicon grease.
(c) Install fuel drain valve.
(d) Install 4 mounting screws and tighten to
1±1.5 N´m (8±13 in. lbs.) torque.
(e) Connect drain hose to drain valve.
(6) Start engine and check for leaks.
FUEL HEATER
DESCRIPTION
The fuel heater assembly is located on the side of
the fuel filter housing (Fig. 3).
The heater/element assembly is equipped with a
temperature sensor (thermostat) that senses fuel
temperature. This sensor is attached to the fuel heat-
er/element assembly.
OPERATION
The fuel heater is used to prevent diesel fuel from
waxing during cold weather operation.
When the temperature is below 45  8 degrees F,
the temperature sensor allows current to flow to the
heater element warming the fuel. When the temper-
ature is above 75  8 degrees F, the sensor stops cur-
rent flow to the heater element.
Battery voltage to operate the fuel heater element
is supplied from the ignition switch and through the
fuel heater relay. Also refer to Fuel Heater Relay.
Fig. 3 FILTER HOUSING
1 - FILTER HOUSING
2 - FUEL HEATER AND THERMOSTAT
3 - FUEL HEATER MOUNTING SCREWS
4 - FUEL HEATER ELEC. CONNECTOR
5 - WIF SENSOR
6 - WIF SENSOR ELEC. CONNECTOR
7 - DRAIN HOSE
8 - DRAIN VALVE MOUNTING SCREWS
9 - DRAIN VALVE
Fig. 4 FILTER COVER (LID)
1 - FILTER COVER
2 - ATTACH SOCKET HERE
DRFUEL DELIVERY - DIESEL 14 - 51
FUEL FILTER / WATER SEPARATOR (Continued)

NOTE: When servicing the steering wheel after
removing the old bolt a new bolt must be used
when installing.
NOTE: When servicing the coupler a new bolt must
be used when installing.
DIAGNOSIS AND TESTING - STEERING
COLUMN
If the vehicle is involved in a front end collision/the
air bag has deployed the column must be inspected.
This inspection will determine if the Column has col-
lapsed. Inspect the column mounting capsules visu-
ally and manually push and pull them to check for
separation or fractures. If capsules are fractured or
have moved the column MUST be replaced.
REMOVAL
WARNING: BEFORE SERVICING THE STEERING
COLUMN THE AIRBAG SYSTEM MUST BE DIS-
ARMED. REFER TO ELECTRICAL RESTRAINT SYS-
TEM FOR SERVICE PROCEDURES. FAILURE TO DO
SO MAY RESULT IN ACCIDENTAL DEPLOYMENT OF
THE AIRBAG AND POSSIBLE PERSONAL INJURY.CAUTION: All fasteners must be torqued to specifi-
cation to ensure proper operation of the steering
column.
(1) Position the front wheelsstraight ahead.
(2) Disconnect the negative (ground) cable from
the battery.
(3) Remove the two switches from the steering
wheel.
(4) Remove the airbag, (Refer to 8 - ELECTRICAL/
RESTRAINTS/DRIVER AIRBAG - REMOVAL).
(5) Remove the steering wheel with special tool
CJ98±1 or an appropriate steering wheel puller.
CAUTION: Ensure the puller bolts are fully engaged
into the steering wheel and not into the clock-
spring, before attempting to remove the wheel. Fail-
ure to do so may damage the steering wheel/
clockspring.
(6) Remove the steering column opening cover
(Refer to 23 - BODY/INSTRUMENT PANEL/STEER-
ING COLUMN OPENING COVER - REMOVAL).
(7) Remove the tilt lever.
(8) Remove the column shrouds (Fig. 2).
(9) Remove the clock spring, (Refer to 8 - ELEC-
TRICAL/RESTRAINTS/CLOCKSPRING -
REMOVAL).
(10) Disconnect the wiring harness to the column.
Fig. 1 STEERING COLUMN
1 - LOCK CYLINDER
2 - GEAR SHIFT LEVER
3 - MOUNTING HOLES
4 - STEERING COLUMN
5 - TILT LEVER
Fig. 2 UPPER & LOWER SHROUDS
1 - UPPER SHROUD
2 - LOWER SHROUD
DRCOLUMN 19 - 7
COLUMN (Continued)

(17) Remove the steering column assembly from
the vehicle. (Fig. 7)
INSTALLATION
WARNING: BEFORE SERVICING THE STEERING
COLUMN THE AIRBAG SYSTEM MUST BE DIS-
ARMED. REFER TO ELECTRICAL RESTRAINT SYS-
TEM FOR SERVICE PROCEDURES. FAILURE TO DO
SO MAY RESULT IN ACCIDENTAL DEPLOYMENT OF
THE AIRBAG AND POSSIBLE PERSONAL INJURY.
CAUTION: All fasteners must be torqued to specifi-
cation to ensure proper operation of the steering
column.
(1) Position the steering column on the dash panel
support and loosely install the mounting nuts.
(2) Firmly slide the steering column upward
against the studs in dash panel and hand tighten the
nuts.
(3) Install the steering shaft coupler on the steer-
ing shaft and loosely install anewbolt.
(4) Center steering column in dash opening and
tighten mounting nuts to 28 N´m (250 in. lbs.).
NOTE: Torque the upper left nut first then the lower
right nut. Then torque the lower left nut then the
upper right nut.
NOTE: A new bolt must be used for reinstallation.
(5) Tighten the coupler bolt to 57 N´m (42 ft. lbs.).(6) Install a new brake light switch (Refer to 8 -
ELECTRICAL/LAMPS/LIGHTING - EXTERIOR/
BRAKE LAMP SWITCH - REMOVAL).
(7) Install the shifter cable. (Refer to 21 - TRANS-
MISSION/TRANSAXLE/AUTOMATIC - 32RH/GEAR
SHIFT CABLE - INSTALLATION)
(8) Connect the wiring harness to the column.
(9) Install the SKIM module.
(10) Install the clockspring(Refer to 8 - ELECTRI-
CAL/RESTRAINTS/CLOCKSPRING - REMOVAL).
(11) Install the shrouds.
(12) Install the steering column opening cover
(Refer to 23 - BODY/INSTRUMENT PANEL/STEER-
ING COLUMN OPENING COVER - INSTALLA-
TION).
(13) Align the spline on the wheel hub to shaft.
(14) Then install the steering wheel and install a
newbolt. Tighten the bolt to 61 N´m (45 ft. lbs.).
(15) Install the airbag (Refer to 8 - ELECTRICAL/
RESTRAINTS/DRIVER AIRBAG - INSTALLATION).
(16) Install the two steering wheel switches.
(17) Install the tilt lever handle.
(18) Install the negative battery terminal.
(19) Test the operation of the horn, Electronic
PRNDL Indicator, lights and any other functions that
are steering column operated.
IGNITION SWITCH
DESCRIPTION
The ignition switch is located on the steering col-
umn. It is used as the main on/off switching device
for most electrical components. The mechanical key
cylinder is used to engage/disengage the electrical
ignition switch.
OPERATION
Vehicles equipped with an automatic trans-
mission and a steering column mounted shifter:
an interlock device is located within the shift cable.
This interlock device is used to lock the transmission
shifter in the PARK position when the key cylinder is
in any position and the brake pedal is not depressed.
DIAGNOSIS AND TESTING - IGNITION SWITCH
TEST AND REPAIR
If the key removal effort is excessive on a vehicle
with a automatic transmission first adjust the shift
linkage, (Refer to 21 - TRANSMISSION/TRANS-
AXLE/AUTOMATIC - 46RE/GEAR SHIFT CABLE -
ADJUSTMENTS).
If the ignition switch effort is excessive remove the
ignition key cylinder from the steering column. (Refer
to 19 - STEERING/COLUMN/LOCK CYLINDER
Fig. 7 STEERING COLUMN
1 - Steering Wheel
2 - Key Cylinder
3 - Gear Shift Lever
4 - Steering Column
5 - Tilt Lever Cable
DRCOLUMN 19 - 9
COLUMN (Continued)