Chrysler neon 1997 Service Manual page 1312

PL
DESCRIPTION AND OPERATION (Continued)
POWER DISTRIBUTION CENTER
The power distribution center (PDC) is located next POWER DISTRI- BUTION POWER DISTRI- BUTION CEN- TER CEN- TER RELAYS SPEED TROL SERVO
to the battery (Fig. 1). The PDC contains the starter
relay, radiator fan relay, A/C compressor clutch relay,
auto shutdown relay, fuel pump relay and several
fuses.
Fig. 1 Power Distribution Center (PDC)
POWERTRAIN CONTROL MODULE
The Powertrain Control Module (PCM) is a digital
computer containing a microprocessor (Fig. 2). The
PCM receives input signals from various switches
and sensors that are referred to as PCM Inputs.
Based on these inputs, the PCM adjusts various
engine and vehicle operations through devices that
are referred to as PCM Outputs.
Fig. 2 Powertrain Control Module (PCM)
PCM Inputs:
• Air Conditioning Controls
• Battery Voltage
• Battery Temperature Sensor
• Brake Switch
• Camshaft Position Sensor
• Crankshaft Position Sensor
CON- WASHER WINDSHIELD BATTERY FUSES BOTTLE FLUID PCM
• Engine Coolant Temperature Sensor
• Fuel Level Sensor
• Ignition Switch
• Intake Air Temperature Sensor
• Knock Sensor
• Manifold Absolute Pressure (MAP) Sensor
• Oxygen Sensors
• Power Steering Pressure Switch
• SCI Receive
• Speed Control Switches
• Throttle Position Sensor
• Transmission Park/Neutral Switch (automatic
transmission)
• Vehicle Speed Sensor
PCM Outputs:
• Air Conditioning WOT Relay
• Auto Shutdown (ASD) Relay
• Charging Indicator Lamp
• Data Link Connector
• Duty Cycle EVAP Canister Purge Solenoid
• EGR Solenoid
• Fuel Injectors
• Fuel Pump Relay
• Generator Field
• Idle Air Control Motor
• Ignition Coils
• Malfunction Indicator (Check Engine) Lamp
• Radiator Fan Relay
• Speed Control Solenoids
• Tachometer
• Torque Convertor Clutch Solenoid
Based on inputs it receives, the PCM adjusts fuel
injector pulse width, idle speed, ignition spark
advance, ignition coil dwell and EVAP canister purge
operation. The PCM regulates the cooling fan, air
conditioning and speed control systems. The PCM
changes generator charge rate by adjusting the gen-
erator field. The PCM also performs diagnostics.
The PCM adjusts injector pulse width (air-fuel
ratio) based on the following inputs.
• Battery voltage
• Coolant temperature
• Intake air temperature
• Exhaust gas content (oxygen sensor)
• Engine speed (crankshaft position sensor)
• Manifold absolute pressure
• Throttle position
The PCM adjusts ignition timing based on the fol-
lowing inputs.
• Coolant temperature
• Intake air temperature
• Engine speed (crankshaft position sensor)
• Knock sensor
• Manifold absolute pressure
• Throttle position
FUEL SYSTEM 14 - 25