1998 DODGE RAM 1500 Ignition control

4.7L V-8
(1) Clean throttle body-to-intake manifold o-ring.(2) Clean mating surfaces of throttle body and
intake manifold.
(3) Install throttle body to intake manifold by posi-
tioning throttle body to manifold alignment pins.
(4) Install three mounting bolts. Tighten bolts to
12 N´m (105 in. lbs.) torque.
(5) Install control cables.
(6) Install vacuum line to throttle body.
(7) Install electrical connectors.
(8) Install air plenum.
5.7L V-8
CAUTION: Do not use spray (carb) cleaners on any
part of the throttle body. Do not apply silicone lubri-
cants to any part of the throttle body.
(1) Clean and check condition of throttle body-to-
intake manifold o-ring.
(2) Clean mating surfaces of throttle body and
intake manifold.
(3) Install throttle body to intake manifold by posi-
tioning throttle body to manifold alignment pins.
(4) Install 4 mounting bolts. Refer to Torque Spec-
ifications.
(5) Install electrical connector.
(6) Install air plenum.
(7)If the throttle body has been changed, the
following procedure must be performed:
(a) Disconnect negative battery cable from bat-
tery. Leave cable disconnected for approximately 90
seconds.
(b) Reconnect cable to battery.
(c) Turn ignition switch ON, but do not crank
engine.
(d) Leave ignition switch ON for a minimum of
10 seconds. This will allow PCM to learn throttle
body electrical parameters.
THROTTLE CONTROL CABLE
REMOVAL
3.7L V-6
CAUTION: Be careful not to damage or kink cable
core wire (within cable sheathing) while servicing
accelerator pedal or throttle cable.
(1) From inside vehicle, hold up accelerator pedal.
Remove plastic cable retainer (clip) and throttle cable
core wire from upper end of pedal arm (Fig. 1). Plas-
tic cable retainer snaps into top of pedal arm.
(2) Remove cable core wire at pedal arm.
(3) From inside vehicle, remove metal clip holding
cable to dashpanel (Fig. 1).
Fig. 31 5.7L V-8 THROTTLE BODY
1 - THROTTLE BODY
2 - ELECTRICAL CONNECTOR
3 - SILICONE SEAL
4 - MOUNTING BOLTS (4)
Fig. 32 5.7L V-8 THROTTLE BODY O-RING
1 - INTAKE MANIFOLD
2 - THROTTLE BODY O-RING
14 - 38 FUEL INJECTION - GASDR
THROTTLE BODY (Continued)

(11) Install air resonator tube to throttle body.
(12) Before starting engine, operate accelerator
pedal to check for any binding.
5.7L V-8
(1) Attach cable to Accelerator Pedal Position Sen-
sor (APPS). Refer to APPS Removal / Installation.
(2) Push cable housing into rubber grommet and
through opening in dash panel.
(3) From inside vehicle, install clip holding cable
to dashpanel (Fig. 1).
(4) From inside vehicle, slide throttle cable core
wire into opening in top of pedal arm.
(5) Push cable retainer (clip) into pedal arm open-
ing until it snaps in place.
(6) Before starting engine, operate accelerator
pedal to check for any binding.
(7) If necessary, use DRB IIItScan Tool to erase
any APPS Diagnostic Trouble Codes (DTC's) from
PCM.
THROTTLE POSITION SENSOR
DESCRIPTION
The 3-wire Throttle Position Sensor (TPS) is
mounted on the throttle body and is connected to the
throttle blade shaft.
The 5.7L V-8 engine does not use a separate TPS
on the throttle body.
OPERATION
The 5.7L V-8 engine does not use a separate Throt-
tle Position Sensor (TPS) on the throttle body.
The 3±wire TPS 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 output voltage 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
3.7L V6
The Throttle Position Sensor (TPS) is mounted to
the throttle body (Fig. 37), or (Fig. 38).
(1) Remove air resonator tube at throttle body.
(2) Disconnect TPS electrical connector.
(3) Remove 2 TPS mounting screws.
(4) Remove TPS.
Fig. 37 TPS LOCATION - 3.7L V-6
1 - THROTTLE POSITION SENSOR (TPS)
2 - MOUNTING SCREWS
3 - IDLE AIR CONTROL MOTOR (IAC)
4 - MOUNTING SCREWS
DRFUEL INJECTION - GAS 14 - 41
THROTTLE CONTROL CABLE (Continued)

The fuel heater element and fuel heater relay
are not computer controlled.
The heater element operates on 12 volts, 300 watts
at 0 degrees F.
DIAGNOSIS AND TESTING - FUEL HEATER
The fuel heater is used to prevent diesel fuel from
waxing during cold weather operation.
NOTE: The fuel heater element, fuel heater relay
and fuel heater temperature sensor are not con-
trolled by the Engine Control Module (ECM).
A malfunctioning fuel heater can cause a wax
build-up in the fuel filter/water separator. Wax
build-up in the filter/separator can cause engine
starting problems and prevent the engine from rev-
ving up. It can also cause blue or white fog-like
exhaust. If the heater is not operating in cold tem-
peratures, the engine may not operate due to fuel
waxing.
The fuel heater assembly is located on the side of
fuel filter housing.
The heater assembly is equipped with a built-in
fuel temperature sensor (thermostat) that senses fuel
temperature. When fuel temperature drops below 45
degrees   8 degrees F, the sensor allows current to
flow to built-in heater element to warm fuel. When
fuel temperature rises above 75 degrees   8 degrees
F, the sensor stops current flow to heater element
(circuit is open).
Voltage to operate fuel heater element is supplied
from ignition switch, through fuel heater relay (also
refer to Fuel Heater Relay), to fuel temperature sen-
sor and on to fuel heater element.
The heater element operates on 12 volts, 300 watts
at 0 degrees F. As temperature increases, power
requirements decrease.
A minimum of 7 volts is required to operate the
fuel heater. The resistance value of the heater ele-
ment is less than 1 ohm (cold) and up to 1000 ohms
warm.
TESTING
(1) Disconnect electrical connector from thermostat
(Fig. 3).
Ambient temperature must be below the circuit
close temperature. If necessary, induce this ambient
temperature by placing ice packs on thermostat to
produce an effective ambient temperature below cir-
cuit close temperature.
Measure resistance across two pins. Operating
range is 0.3 Ð 0.45 Ohms.
(2) If resistance is out of range, remove thermostat
and check resistance across terminal connections of
heater. The heater can be checked at room tempera-
ture. Operating range is 0.3 - 0.45 Ohms.(3) Replace heater if resistance is not within oper-
ating range.
(4) If heater is within operating range, replace
heater thermostat.
REMOVAL
REMOVAL/INSTALLATION
The fuel heater/element/sensor assembly is located
inside of the fuel filter housing. Refer to Fuel Filter/
Water Separator Removal/Installation for procedures.
FUEL HEATER RELAY
DESCRIPTION
The fuel heater relay is located in Power Distribu-
tion Center (PDC) (Fig. 5). Refer to label on inside of
PDC cover for relay location.
OPERATION
Battery voltage to operate the fuel heater element
is supplied from the ignition switch through the fuel
heater relay.The fuel heater element and fuel
heater relay are not computer controlled.
REMOVAL
The fuel heater relay is located in the Power Dis-
tribution Center (PDC) (Fig. 6). Refer to label under
PDC cover for relay location.
(1) Remove PDC cover.
(2) Remove relay from PDC.
Fig. 5 POWER DISTRIBUTION CENTER LOCATION
1 - CLIP
2 - BATTERY
3 - TRAY
4 - NEGATIVE CABLE
5 - POSITIVE CABLE
6 - CLIP
7 - FENDER INNER SHIELD
8 - POWER DISTRIBUTION CENTER
14 - 52 FUEL DELIVERY - DIESELDR
FUEL HEATER (Continued)

CASCADE OVERFLOW VALVE
DESCRIPTION
The cascade overflow valve is located on the top/
rear side of the fuel injection pump (Fig. 25).
OPERATION
When the fuel control actuator (FCA) is opened,
the maximum amount of fuel is being delivered to
the fuel injection pump. The cascade valve regulates
how much excess fuel is used for lubrication of the
injection pump, and is also used to route excess fuel
through the drain circuit and back into the fuel tank.
REMOVAL
REMOVAL/INSTALLATION
The cascade overflow valve is not serviced sepa-
rately.
WATER IN FUEL SENSOR
DESCRIPTION
The Water-In-Fuel (WIF) sensor is located on the
side of the fuel filter/water separator canister (Fig.
26).
OPERATION
The sensor sends an input to the Engine Control
Module (ECM) when it senses water in the fuel filter/
water separator. As the water level in the filter/sep-
arator increases, the resistance across the WIF
sensor decreases. This decrease in resistance is sent
as a signal to the ECM and compared to a high
water standard value. Once the value reaches 30 to
40 kilohms, the ECM will activate the water-in-fuel
warning lamp through CCD bus circuits. This all
takes place when the ignition key is initially put in
the ON position. The ECM continues to monitor the
input while the engine is running.
REMOVAL
The Water-In-Fuel (WIF) sensor is located at the
side of fuel filter/water separator canister. Refer to
Fuel Filter/Water Separator Removal/Installation for
WIF sensor removal/installation procedures.
Fig. 25 OVERFLOW VALVE
1 - BANJO BOLTS
2 - PUMP MOUNTING NUTS (3)
3 - FUEL INJECTION PUMP
4 - CASCADE OVERFLOW VALVE
Fig. 26 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
14 - 66 FUEL DELIVERY - DIESELDR

BTSI FUNCTION CHECK
(1) Verify removal of ignition key allowed in PARK
position only.
(2) When the shift lever is in PARK, the ignition
key cylinder should rotate freely from off to lock.
When the shifter is in any other position, the ignition
key should not rotate from off to lock.
(3) Shifting out of PARK should be possible when
the ignition key cylinder is in the off position.
(4) Shifting out of PARK should not be possible
while applying normal force, and ignition key cylin-
der is in the run or start positions, unless the foot
brake pedal is depressed approximately 1/2 inch
(12mm).
(5) Shifting out of PARK should not be possible
when the ignition key cylinder is in the accessory or
lock position.
(6) Shifting between any gear and NEUTRAL, or
PARK, may be done without depressing foot brake
with ignition switch in run or start positions.
(7) Engine starts must be possible with shifter
lever in PARK or NEUTRAL positions only. Engine
starts must not be possible in any position other than
PARK or NEUTRAL.
(8) With shifter lever in the:
²PARK position - Apply upward force on the shift
arm and remove pressure. Engine starts must be
possible.²PARK position - Apply downward force on the
shift arm and remove pressure. Engine starts must
be possible.
²NEUTRAL position - Normal position. Engine
starts must be possible.
²NEUTRAL position - Engine running and brakes
applied, apply upward force on the shift arm. Trans-
mission shall not be able to shift from neutral to
reverse.
ELECTRONIC GOVERNOR
DESCRIPTION
Governor pressure is controlled electronically. Com-
ponents used for governor pressure control include:
²Governor body
²Valve body transfer plate
²Governor pressure solenoid valve
²Governor pressure sensor
²Fluid temperature thermistor
²Throttle position sensor (TPS)
²Transmission speed sensor
²Powertrain control module (PCM)
GOVERNOR PRESSURE SOLENOID VALVE
The solenoid valve is a duty-cycle solenoid which
regulates the governor pressure needed for upshifts
and downshifts. It is an electro-hydraulic device
located in the governor body on the valve body trans-
fer plate (Fig. 76).
Fig. 75 Brake Transmission Interlock Mechanism
1 - STEERING COLUMN
2 - GEARSHIFT CABLE
3 - GEARSHIFT CABLE LOCK TAB
4 - BTSI SOLENOID LOCK TAB
5 - BTSI CONNECTOR
Fig. 76 Governor Pressure Solenoid Valve
1 - SOLENOID FILTER
2 - GOVERNOR PRESSURE SOLENOID
DRAUTOMATIC TRANSMISSION - 48RE 21 - 197
BRAKE TRANSMISSION SHIFT INTERLOCK SYSTEM (Continued)

ADJUSTMENTS - THROTTLE VALVE CABLE
A correctly adjusted throttle valve cable will cause
the throttle lever on the transmission to move simul-
taneously with the throttle body lever from the idle
position. Proper adjustment will allow simultaneous
movement without causing the transmission throttle
lever to either move ahead of, or lag behind the lever
on the throttle body.
ADJUSTMENT VERIFICATION
(1) Turn ignition key to OFF position.
(2) Remove air cleaner.
(3) Verify that lever on throttle body is at curb idle
position (Fig. 224). Then verify that the transmission
throttle lever (Fig. 225) is also at idle (fully forward)
position.
(4) Slide cable off attachment stud on throttle body
lever.
(5) Compare position of cable end to attachment
stud on throttle body lever:
²Cable end and attachment stud should be
aligned (or centered on one another) to within 1 mm
(0.039 in.) in either direction (Fig. 226).
²If cable end and attachment stud are misaligned
(off center), cable will have to be adjusted as
described in Throttle Valve Cable Adjustment proce-
dure.
Fig. 225 Throttle Valve Cable at Transmission
1 - TRANSMISSION SHIFTER CABLE
2 - THROTTLE VALVE CABLE
3 - TRANSFER CASE SHIFTER CABLE
4 - TRANSFER CASE SHIFTER CABLE BRACKET RETAINING
BOLT(1OR2)
5 - THROTTLE VALVE CABLE BRACKET RETAINING BOLT
6 - ELECTRICAL CONNECTORS
7 - TRANSMISSION FLUID LINES
Fig. 226 Throttle Valve Cable at Throttle Linkage
1 - THROTTLE LINKAGE
2 - THROTTLE VALVE CABLE LOCKING CLIP
3 - THROTTLE VALVE CABLE
Fig. 224 Throttle Valve Cable Attachment - At
Engine
1 - THROTTLE VALVE CABLE
2 - CABLE BRACKET
3 - THROTTLE BODY LEVER
4 - ACCELERATOR CABLE
5 - SPEED CONTROL CABLE
21 - 254 AUTOMATIC TRANSMISSION - 48REDR
THROTTLE VALVE CABLE (Continued)

OPERATION
At key-on, overdrive operation is allowed. Pressing
the switch once causes the tow/haul overdrive OFF
mode to be entered and the Tow/Haul lamp to be illu-
minated. Pressing the switch a second time causes
normal overdrive operation to be restored and the
tow/haul lamp to be turned off. The tow/haul over-
drive OFF mode defaults to ON after the ignition
switch is cycled OFF and ON. The normal position
for the control switch is the ON position. The switch
must be in this position to energize the solenoid and
allow a 3-4 upshift. The control switch indicator light
illuminates only when the tow/haul overdrive switch
is turned to the OFF position, or when illuminated
by the transmission control module.
DIAGNOSIS AND TESTING - OVERDRIVE
ELECTRICAL CONTROLS
The tow/haul overdrive off switch, valve body sole-
noid, case connectors and related wiring can all be
tested with a 12 volt test lamp or a volt/ohmmeter.
Check continuity of each component when diagnosis
indicates this is necessary.
Switch and solenoid continuity should be checked
whenever the transmission fails to shift into fourth
gear range.
REMOVAL
(1) Using a plastic trim tool, remove the tow/haul
overdrive off switch retainer from the shift lever (Fig.
237).(2) Pull the switch outwards to release it from the
connector in the lever (Fig. 238)
INSTALLATION
NOTE: There is enough slack in the wire to pull out
the connector from the lever.
(1) Pull the connector out of the lever just enough
to grasp it.
CAUTION: Be careful not to bend the pins on the
tow/haul overdrive off switch. Use care when
installing the switch, as it is not indexed, and can
be accidentally installed incorrectly.
(2) Install the tow/haul overdrive off switch into
the connector (Fig. 239)
(3) Push the tow/haul overdrive off switch and wir-
ing into the shift lever.
(4) Install the tow/haul overdrive off switch
retainer onto the shift lever.
Fig. 237 Tow/Haul Overdrive Off Switch Retainer
Fig. 238 Remove the Tow/Haul Overdrive Off Switch
Fig. 239 Install the Tow/Haul Overdrive Off Switch
21 - 262 AUTOMATIC TRANSMISSION - 48REDR
TOW/HAUL OVERDRIVE SWITCH (Continued)

TRANSMISSION RANGE
SENSOR
DESCRIPTION
The Transmission Range Sensor (TRS) (Fig. 240)
has 3 primary functions:
²Provide a PARK/NEUTRAL start signal to the
engine controller and the starter relay.
²Turn the Back-up lamps on when the transmis-
sion is in REVERSE and the engine (ignition) is on.
²Provide a transmission range signal to the
instrument cluster.
The sensor is mounted in the transmission housing
near the valve body, just above the pan rail. It's in
the same position as the Park/Neutral switch on
other transmissions. The TRS contacts a cammed
surface on the manual valve lever. The cammed sur-
face translates the rotational motion of the manual
lever into the linear motion of the sensor. The
cammed surface on the manual lever is comprised of
two parts controlling the TRS signal: The insulator
portion contacts the switch poppet when the manual
lever is not in PARK or NEUTRAL. The manual
lever itself contacts the poppet when the lever is inPARK or NEUTRAL; providing a ground for the sig-
nal from the starter relay and the JTEC engine con-
troller.
OPERATION
As the switch moves through its linear motion (Fig.
241) contacts slide across a circuit board which
changes the resistance between the range sensing
pins of the switch. A power supply on the instrument
cluster provides a regulated voltage signal to the
switch. The return signal is decoded by the cluster,
which then controls the PRNDL display to corre-
spond with the correct transmission range. A bus
message of transmission range is also sent by the
cluster. In REVERSE range a second contact set
closes the circuit providing power to the reverse
lamps.
Fig. 240 Transmission Range Sensor
Fig. 241 Transmission Range Sensor Linear
Movement
DRAUTOMATIC TRANSMISSION - 48RE 21 - 263