Dodge RAM TRUCK 1500 1995 Service Manual page 1175

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COMPONENT DESCRIPTION/SYSTEM OPERATION—DIESEL ENGINE 14 - 93
The sensor is located on the top of the intake man­
ifold and to the rear of the intake manifold air heater
(Fig. 8).
FRONT OF ENGINE
A I R TEMPERATURE
S E N S O R
S E N S O R
ELECTRICAL
C O N N E C T O R
INTAKE
M A N I F O L D
(UPPER H A L F )
S H U V B O W N S O L E N O I D
S O L E N O I D E L E C T R I C A L
CONNECTOR
mi
4-93
Fig. 8 Mir Temperature Sensor Location—Diesel
Also refer to Intake Manifold Heater Relays—-PCM
Pin #15—PCM Output for additional information.
Refer to the Diesel Engine—General Diagnosis sec­
tion of this group for diagnostic procedures.
THROTTLE POSITION SENSOR—PCM PIN
#22—PCM INPUT
The throttle position sensor (TPS) is used only on
vehicles equipped with an automatic transmission if
equipped with a diesel engine. It is not used with the
manual transmission.
The TPS is mounted on the side of the fuel injec­
tion pump (Fig. 9). The TPS provides an input to the
PCM. It senses how far the throttle is open (past the
idle position). The PCM uses the TPS input, along
with vehicle speed sensor and engine speed sensor
inputs to determine 3-4 upshift (overdrive) and 4-3
downshift. It is also used with the vehicle speed sen­
sor and engine speed sensor inputs to engage and
disengage the torque convertor solenoid. This sole­
noid is used for torque convertor engagement.
The TPS is a linear potentiometer. The PCM sup­
plies 5 volts to the sensor. TPS output voltage to the
PCM will vary. At idle speed, the voltage should be
1.0 volt (± .2 volts). At wide open throttle (WOT), the
output voltage must be 2.2-to-2.9 volts higher than at
idle speed.
ELECTRICAL
CONNECTOR
THROTTLE
POSITION
SENSOR
CENTER TERMINAL
IS OUTPUT WIRE
MOUNTING
BOLTS (2)
J9414-91
Fig. 9 Throttle Position Sensor Location—Diesel
ENGINE SPEED SENSOR—PCM PIN #24—PCM
INPUT
The engine speed (rpm) sensor is mounted to the
front of engine (Fig. 10). It generates an rpm signal
to the PCM. The engine speed sensor input is used
along with the vehicle speed sensor and throttle po­
sition sensor (TPS) inputs to determine when to shift
the automatic transmission into and out of overdrive.
The speed sensor signal is also used as an input for
the ASD relay (for control of generator field), vehicle
speed control, torque convertor electrical engagement
and instrument panel mounted tachometer.
DATA LINK CONNECTOR—PCM PIN #25—PCM
OUTPUT
The data link connector (diagnostic scan tool con­
nector) links the Diagnostic Readout Box (DRB) scan
tool or the Mopar Diagnostic System (MDS) with the
powertrain control module (PCM). The data link con­
nector is located in the engine compartment (Fig. 11).
For operation of the DRB scan tool, refer to the ap­
propriate Powertrain Diagnostic Procedures service
manual.
The data link connector uses two different pins on
the PCM. Pin #25 is for Data Link Transmit and pin
#45 is for Data Link Receive.
AIR CONDITIONING (A/C) CONTROLS—PCM PIN
#27—PCM INPUT
The A/C control system information applies to fac­
tory installed air conditioning units.
A/C REQUEST SIGNAL: When either the A/C or
Defrost mode has been selected and the A/C low and