Chrysler RAM TRUCK 2500 1994 Service Manual page 986

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.
MOUNTING SCREWS
MAP SENSOR
RUBBER FITTING
AIR
PASSAGE
VIEW FROM BOTTOM J9314-87
Fig. 28 Air Control Passage—3.9U5.2U5.9L Engines
VACUUM
FITTING
THROTTLE
P O S I T I O N
S E N S O R
THROTTLE
BODY
IDLE AIR
PASSAGE
V I E W FROM BOTTOM
IDLE AIR
C O N T R O L (IAC)
MOTOR
J9414-48
Fig. 29 Air Control Passage—8.0L ¥-10 Engine
IDLE AIR CONTROL (IAC) MOTOR—PIN #40—PCM
OUTPUT
Pin #40 controls one of the circuits for operation of
the IAC motor. Refer to Idle Air Control (IAC)
M o t o r - P i n #39—PCM Output for information.
OXYGEN ( 0 2 S ) SENSOR—PCM PIN #41—PCM
INPUT
Refer to Oxygen (02S) Sensor-PCM Pin
#23—PCM Input for information.
TRANSMISSION TEMPERATURE SENSOR—PCM
PIN #42—PCM INPUT
AUTOMATIC TRANSMISSIONS ONLY
The transmission temperature sensor is a variable,
thermistor type. I t reacts to temperature changes. A t
cold transmission oil temperatures, its resistance is
high. As temperatures increase, its resistance will de­
crease.
The transmission temperature sensor is used on
models equipped with certain heavy-duty options and
an automatic transmission. Its purpose is to help
control transmission overheating. I f transmission
overheating has been determined by this sensor
(temp, above approximately 280 degrees F), an input
is sent to the powertrain control module (PCM). The
PCM will then force a 4-3 downshift. Once transmis­
sion temperature has cooled below specifications, a
3-4 upshift will be allowed. An instrument panel
mounted transmission temperature warning lamp
(Fig. 23) is also used.
This sensor is located i n the transmission cooling
line on the side of the transmission (Fig. 30).
TRANSMISSION C O O L I N G
LINE
T R A N S M I S S I O N
TEMPERATURE S E N S O R
J9414-46
Fig. 30 Transmission Temperature Sensor
Location—Typical
TACHOMETER—PCM PIN #43—PCM OUTPUT
The powertrain control module (PCM) supplies en­
gine rpm values to the instrument cluster mounted
tachometer (if equipped). Refer to Group 8E for ta­
chometer information.
CAMSHAFT POSITION SENSOR—PCM PIN
#44—PCM INPUT
A fuel sync signal is provided by the camshaft po­
sition sensor. The sync signal from this sensor works
in conjunction with the crankshaft position sensor to
provide the powertrain control module (PCM) with
inputs. This is done to establish and maintain correct
injector firing order. The sensor is located-in the ig­
nition distributor (Fig. 31—3.9L/5.2L/5.9L engine), or