Chrysler RAM TRUCK 2500 1994 Service Manual page 988

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:
• Park/neutral switch
• Vehicle speed sensor
• Throttle position sensor
Refer to Group 8H for further speed control infor­
mation.
AUTOMATIC SHUT DOWN (ASD) RELAY—PCM PIN
#51—PCM OUTPUT
This circuit (pin #51) controls operation of both the
ASD and fuel pump relays.
The ASD relay is located i n the power distribution
center (PDC). The PDC is located next to the battery
in the engine compartment (Fig. 34). For the location
of the relay within the PDC,- refer to PDC cover.
Fig. 34 Power Distribution Center (PDC) Location
The ASD relay, after receiving signals from the
crankshaft and camshaft position sensors, will supply
battery voltage to the fuel injectors, ignition coil(s),
generator field winding and oxygen (02S) sensor(s)
heating element. I f these signals are not received by
the PCM after approximately one second of engine
cranking (start-up), the ASD relay will be shut down.
The ground circuit for the coil i n the ASD relay is
controlled by the powertrain control module (PCM).
The PCM operates the relay by switching the ground
circuit ON and OFF.
Also refer to Fuel Pump Relay-PCM Pin
#51—PCM Output for additional information.
FUEL PUMP RELAY—PCM PIN #51—PCM
OUTPUT
The PCM energizes the electric fuel pump through
the fuel pump relay. Battery voltage is applied to the
fuel pump relay when the ignition key is ON. The re­
lay is energized when a ground signal is provided by
pin #51 on the PCM.
Refer to Automatic Shut Down Relay—PCM Pin
#51—PCM Output for additional information.
The fuel pump will operate for approximately one
second unless the engine is operating or the starter
motor is engaged.
The fuel pump relay is located i n the power distri­
bution center (PDC). The PDC is located next to the
battery i n the engine compartment (Fig. 34). For the
location of the relay within the PDC, refer to PDC
cover.
EVAP CANISTER PURGE SOLENOID—PCM PIN
#52—PCM OUTPUT
This circuit controls a ground signal for operation
of the EVAP Canister Purge Solenoid.
Refer to Group 25, Emission Control System. See
EVAP Canister Purge Solenoid.
SPEED CONTROL—PCM PINS #53 AND #33—PCM
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. 35) controls operation of the
transmission mounted torque convertor (TCC) sole­
noid used for torque convertor engagement.
TORQUE CONVERTER CLUTCH
AND OVERDRIVE SOLENOID
ELECTRICAL CONNECTOR
VEHICLE
SPEED
SENSOR J9414-59
Fig. 35 Electrical Connections at Transmission—
TCC and Overdrive Solenoids
The powertrain control module (PCM) will deter­
mine when to engage and disengage the solenoid by
monitoring vehicle miles per hour (mph) versus the
output voltage of the throttle position sensor. Also
needed are various inputs from: