1998 DODGE RAM 1500 Tps

(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)

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
threads of a new oxygen sensor.
(1) Install O2S sensor. Tighten to 30 N´m (22 ft.
lbs.) torque.
(2) Connect O2S sensor wire connector.
(3) Lower 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 (or ECM-
Diesel) that the PTO has been engaged. The PCM (or
ECM) will disable (temporarily shut down) certain
OBD II diagnostic trouble codes when the PTO is
engaged.
JTEC and NGC Engine Controllers: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 determine that the
PTO has been activated.
CM 845 or CM 848 Diesel Engine Controllers:
When the aftermarket PTO switch has been engaged,
a 12V + signal is sent through circuit G113 to ECM
pin B38. The ECM will then sense and determine
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.
5.7L V-8 Engine:
The throttle body on the 5.7L engine is an electri-
cally controlled unit. A mechanical cable is not used
to connect the throttle body to the accelerator pedal.
The Accelerator Pedal Position Sensor (APPS) alongwith inputs from other sensors sets the throttle blade
to pre-determined positions.
Except 5.7L V-8 Engine:
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
3.7L V-6
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 air cleaner tube at throttle body.
(2) Disconnect throttle body electrical connectors
at IAC motor and TPS.
(3) Remove all control cables from throttle body
(lever) arm. Refer to the Accelerator Pedal and Throt-
tle Cable section for removal/installation procedures.
(4) Disconnect necessary vacuum lines at throttle
body.
(5) Remove 3 throttle body mounting bolts (Fig.
28).
(6) Remove throttle body from intake manifold.
(7) Check condition of old throttle body-to-intake
manifold o-ring (Fig. 29).
4.7L V-8
(1) Remove air duct and air resonator box at throt-
tle body.
(2) Disconnect throttle body electrical connectors
at IAC motor and TPS (Fig. 30).
(3) Remove vacuum line at throttle body.
(4) Remove all control cables from throttle body
(lever) arm. Refer to Accelerator Pedal and Throttle
Cable.
(5) Remove three throttle body mounting bolts
(Fig. 30).
(6) Remove throttle body from intake manifold.
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) Remove air duct and air resonator box at throt-
tle body.
14 - 36 FUEL INJECTION - GASDR
OXYGEN SENSOR (Continued)

(2) Disconnect electrical connector at throttle body
(Fig. 31).
(3) Remove 4 throttle body mounting bolts (Fig.
31).
(4) Remove throttle body from intake manifold.
(5) Check condition of throttle body o-ring (Fig.
32).(6) If the throttle body has been changed, the fol-
lowing 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.
INSTALLATION
3.7L V-6
(1) Check condition of throttle body-to-intake man-
ifold o-ring. Replace as necessary.
(2) Clean mating surfaces of throttle body and
intake manifold.
(3) Install throttle body-to-intake manifold o-ring.
(4) Install throttle body to intake manifold.
(5) Install 3 mounting bolts. Tighten bolts to 12
N´m (105 in. lbs.) torque.
(6) Install control cables.
(7) Install electrical connectors.
(8) Install necessary vacuum lines.
(9) Install air plenum.
Fig. 28 THROTTLE BODY MOUNTING BOLTS - 3.7L
V-6
1 - THROTTLE BODY
2 - MOUNTING BOLTS (3)
Fig. 29 THROTTLE BODY O-RING - 3.7L V-6
1 - INTAKE MANIFOLD
2 - THROTTLE BODY O-RING
Fig. 30 THROTTLE BODY MOUNTING BOLTS - 4.7L
V-8
1 - MOUNTING BOLTS (3)
2 - THROTTLE BODY
3 - IAT SENSOR CONNECTOR
4 - IAC MOTOR CONNECTOR
5 - TPS CONNECTOR
DRFUEL INJECTION - GAS 14 - 37
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)

4.7L V-8
The TPS is located on the throttle body (Fig. 39).
(1) Remove air duct and tube at throttle body.
(2) Disconnect TPS electrical connector.
(3) Remove two TPS mounting bolts (screws) (Fig.
39).
(4) Remove TPS from throttle body.
5.7L V-8
The 5.7L V-8 engine does not use a separate Throt-
tle Position Sensor (TPS) on the throttle body.
Fig. 38 TPS INSTALLATION - 3.7 V-6
1 - THROTTLE BODY
2 - TPS
3 - THROTTLE BODY SHAFT
4 - SOCKET LOCATING TANGS
Fig. 39 TPS LOCATION - 4.7L
1 - THROTTLE BODY
2 - TPS
3 - IAC MOTOR
4 - IAT SENSOR
5 - MOUNTING SCREWS
14 - 42 FUEL INJECTION - GASDR
THROTTLE POSITION SENSOR (Continued)

INSTALLATION
3.7L V-6
The Throttle Position Sensor (TPS) is mounted to
the throttle body (Fig. 37).
The throttle shaft end of throttle body slides into a
socket in TPS (Fig. 40). The TPS must be installed so
that it can be rotated a few degrees. (If sensor will
not rotate, install sensor with throttle shaft on other
side of socket tangs). The TPS will be under slight
tension when rotated.
(1) Install TPS and retaining screws.
(2) Tighten screws to 7 N´m (60 in. lbs.) torque.
(3) Connect TPS electrical connector to TPS.
(4) Manually operate throttle (by hand) to check
for any TPS binding before starting engine.
(5) Install air cleaner tube to throttle body.
4.7L V-8
The throttle shaft end of throttle body slides into a
socket in TPS (Fig. 41). The TPS must be installed so
that it can be rotated a few degrees. If sensor will
not rotate, install sensor with throttle shaft on other
side of socket tangs. The TPS will be under slight
tension when rotated.
(1) Install TPS and two retaining bolts.
(2) Tighten bolts to 7 N´m (60 in. lbs.) torque.
(3) Manually operate throttle control lever by hand
to check for any binding of TPS.
(4) Connect TPS electrical connector to TPS.
(5) Install air duct/air box to throttle body.
Fig. 40 TPS INSTALLATION - 3.7L
1 - THROTTLE BODY
2 - TPS
3 - THROTTLE BODY SHAFT
4 - SOCKET LOCATING TANGS
Fig. 41 TPS INSTALLATION - 4.7L
1 - THROTTLE BODY
2 - LOCATING TANGS
3 - THROTTLE POSITION SENSOR
4 - SOCKET
5 - THROTTLE SHAFT
DRFUEL INJECTION - GAS 14 - 43
THROTTLE POSITION SENSOR (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
NO KICKDOWN OR
NORMAL DOWNSHIFT1. Throttle Linkage Mis-adjusted. 1. Adjust linkage.
2. Accelerator Pedal Travel
Restricted.2. Verify floor mat is not under pedal, repair
worn accelerator cable or bent brackets.
3. Valve Body Hydraulic Pressures
Too High or Too Low Due to Valve
Body Malfunction or Incorrect
Hydraulic Control Pressure
Adjustments.3. Perform hydraulic pressure tests to
determine cause and repair as required.
Correct valve body pressure adjustments as
required.
4. Governor Circuit Electrical Fault. 4. Test with DRBTscan tool and repair as
required.
5. Valve Body Malfunction. 5. Perform hydraulic pressure tests to
determine cause and repair as required.
Correct valve body pressure adjustments as
required.
6. TPS Malfunction. 6. Replace sensor, check with DRBTscan
tool.
7. PCM Malfunction. 7. Check with DRBTscan tool and replace
if required.
8. Valve Body Malfunction. 8. Repair sticking 1-2, 2-3 shift valves,
governor plugs, 3-4 solenoid, 3-4 shift
valve, 3-4 timing valve.
STUCK IN LOW GEAR
(WILL NOT UPSHIFT)1. Throttle Linkage Mis-adjusted/
Stuck.1. Adjust linkage and repair linkage if worn
or damaged. Check for binding cable or
missing return spring.
2. Gearshift Linkage Mis-adjusted. 2. Adjust linkage and repair linkage if worn
or damaged.
3. Governor Component Electrical
Fault.3. Check operating pressures and test with
DRBTscan tool, repair faulty component.
4. Front Band Out of Adjustment. 4. Adjust Band.
5. Clutch or Servo Malfunction. 5. Air pressure check operation of clutches
and bands. Repair faulty component.
CREEPS IN NEUTRAL 1. Gearshift Linkage Mis-adjusted. 1. Adjust linkage.
2. Rear Clutch Dragging/Warped. 2. Disassemble and repair.
3. Valve Body Malfunction. 3. Perform hydraulic pressure test to
determine cause and repair as required.
21 - 150 AUTOMATIC TRANSMISSION - 48REDR
AUTOMATIC TRANSMISSION - 48RE (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
GROWLING, GRATING OR
SCRAPING NOISES1. Drive Plate Broken. 1. Replace.
2. Torque Converter Bolts Hitting
Dust Shield.2. Dust shield bent. Replace or repair.
3. Planetary Gear Set Broken/
Seized.3. Check for debris in oil pan and repair as
required.
4. Overrunning Clutch Worn/Broken. 4. Inspect and check for debris in oil pan.
Repair as required.
5. Oil Pump Components Scored/
Binding.5. Remove, inspect and repair as required.
6. Output Shaft Bearing or Bushing
Damaged.6. Remove, inspect and repair as required.
7. Clutch Operation Faulty. 7. Perform air pressure check and repair as
required.
8. Front and Rear Bands Mis-
adjusted.8. Adjust bands.
DRAGS OR LOCKS UP 1. Fluid Level Low. 1. Check and adjust level.
2. Clutch Dragging/Failed 2. Air pressure check clutch operation and
repair as required.
3. Front or Rear Band Mis-adjusted. 3. Adjust bands.
4. Case Leaks Internally. 4. Check for leakage between passages in
case.
5. Servo Band or Linkage
Malfunction.5. Air pressure check servo operation and
repair as required.
6. Overrunning Clutch Worn. 6. Remove and inspect clutch. Repair as
required.
7. Planetary Gears Broken. 7. Remove, inspect and repair as required
(look for debris in oil pan).
8. Converter Clutch Dragging. 8. Check for plugged cooler. Perform flow
check. Inspect pump for excessive side
clearance. Replace pump as required.
NO 4-3 DOWNSHIFT 1. Circuit Wiring and/or Connectors
Shorted.1. Test wiring and connectors with test lamp
and volt/ohmmeter. Repair wiring as
necessary. Replace connectors and/or
harnesses as required.
2. PCM Malfunction. 2. Check PCM operation with DRBTscan
tool. Replace PCM only if faulty.
3. TPS Malfunction 3. Check TPS with DRBTscan tool at PCM.
4. Lockup Solenoid Not Venting. 4. Remove valve body and replace solenoid
assembly if plugged or shorted.
5. Overdrive Solenoid Not Venting. 5. Remove valve body and replace solenoid
if plugged or shorted.
6. Valve Body Valve Sticking. 6. Repair stuck 3-4 shift valve or lockup
timing valve.
21 - 152 AUTOMATIC TRANSMISSION - 48REDR
AUTOMATIC TRANSMISSION - 48RE (Continued)