Dodge RAM TRUCK 1500 1995 Service Manual page 1179

COMPONENT DESCRIPTION/SYSTEM OPERATION—DIESEL ENGINE 14 - 97
SPEED CONTROL—PCM PINS #48, #49 AND
#50—PCM INPUT
The speed control system provides three separate
inputs to the powertrain control module (PCM); On/
Off, Set and Resume. The On/Off input informs the
PCM that the speed control system has been acti­
vated. The Set input informs the PCM that a fixed
vehicle speed has been selected. The Resume input
indicates to the PCM that the previous fixed speed is
requested.
The speed control operating range is from 50 km/h
to 142 km/h (35 to 85 mph). Inputs that effect speed
control operation are:
• Brake switch position
• Park/neutral switch
© Vehicle speed sensor
• Engine speed sensor
• Throttle position sensor (auto, trans, only)
Refer to Group 8H for further speed control infor­
mation.
AUTOMATIC SHUTDOWN (ASD) RELAY—PCM PIN
#51—PCM OUTPUT
This circuit controls operation of the ASD relay. It
provides the necessary power to operate the genera­
tor field control for charging system operation.
The ASD relay is located in the power distribution
center (PDC). The PDC is located next to the battery
in the engine compartment (Fig. 14). For the location
of the relay within the PDC, refer to PDC cover.
The ground circuit for the coil in the ASD relay is
controlled by the powertrain control module (PCM).
The PCM operates the relay by switching the ground
circuit ON and OFF.
SPEED CONTROL—PCM PINS #S3 AND #33—PCi
OUTPUT
These two circuits control vent and vacuum opera­
tion of the speed control solenoids.
TORQUE CONVERTOR CLUTCH (TCC) SOLENOID—
PCM PIN #54—PCM OUTPUT
AUTOMATIC TRANSMISSION
This circuit (Fig. 18) controls operation of the
transmission mounted torque convertor (TCC) sole­
noid used for torque convertor engagement.
The powertrain control module (PCM) will deter­
mine when to engage and disengage the solenoid by
TORQUE CONVERTER CLUTCH
AND OVERDRIVE SOLENOID
ELECTRICAL CONNECTOR
VEHICLE
SPEED
SENSOR J9414-59
Fig. 18 Electrical Connections at Transmission—
TCC and Overdrive Solenoids
monitoring vehicle miles per hour (mph). Also needed
are various inputs from the module timer, engine
rpm and throttle position sensor.
OVERDRIVE SOLENOID—PCM PIN #55—PCM
OUTPUT
AUTOMATIC TRANSMISSION
This circuit controls operation of the transmission
mounted overdrive solenoid (Fig. 18) used for over­
drive operation. The powertrain control module
(PCM) will determine when to engage and disengage
the solenoid by monitoring engine rpm and vehicle
speed, versus output voltage of the throttle position
sensor. Also needed are various inputs from the mod­
ule timer.
AUTOMATIC SHUTDOWN (ASD) SENSE—PCM PIN
#57—PCM INPUT
A 12 volt signal at this input indicates to the PCM
that the ASD has been activated. The ASD relay is
located in the power distribution center (PDC). The
PDC is located next to the battery in the engine com­
partment (Fig. 14). For the location of the relay
within the PDC, refer to PDC cover.
This input is used only to sense that the ASD relay
is energized. If the powertrain control module (PCM)
does not see 12 volts + at this input when the ASD
should be activated, it will set a diagnostic trouble
code (DTC).