Chrysler RAM TRUCK 2500 1994 Service Manual page 987

14 - 46 FUEL SYSTEM
•
in the timing chain case/cover on the left-front side of
the engine (Fig. 3 2 - 8 . 0 L V-10 engine).
Refer to Camshaft Position Sensor i n Group 8D, Ig­
nition System for more information.
Fig. 32 Camshaft Position Sensor—8.0L V-10 Engine
DATA LINK CONNECTOR—PCM PIN #45—PCM
INPUT
Refer to Data Link Connector—PCM P I N
# 2 5 - P C M Output for information.
CCD BUS(-)—PCM PIN #46—PCM OUTPUT
Various modules exchange information through a
communications port called the CCD BUS(-).
VEHICLE SPEED SENSOR—PCM PIN #47—PCM
INPUT
The speed sensor (Fig. 33) is located i n the exten­
sion housing of the transmission (2WD) or on the
transfer case extension housing (4WD). The sensor
input is used by the powertrain control module
(PCM) to determine vehicle speed and distance trav­
eled.
The speed sensor generates 8 pulses per sensor
revolution. These signals, i n conjunction with a
closed throttle signal from the throttle position sen­
sor, indicate a closed throttle deceleration to the
PCM. When the vehicle is stopped at idle, a closed
throttle signal is received by the PCM (but a speed
sensor signal is not received).
Under deceleration conditions, the PCM adjusts the
idle air control (IAC) motor to maintain a desired
MAP value. Under idle conditions, the PCM adjusts
the IAC motor to maintain a desired engine speed.
I n addition to determining distance and vehicle
speed, the output from the sensor is used to help con­
trol:
• Speed control operation
• Transmission overdrive operation
• Transmission torque converter electrical operation
• Idle air control (IAC) motor for engine idle speed
• Fuel injector pulse width
SENSOR
ELECTRICAL
CONNECTOR
J9414-60
Fig. 33 Vehicle Speed Sensor—Typical
SPEED CONTROL—PCM PINS #48 #4S 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.