Chrysler 2004 Concorde Service Manual page 255

LH
POWERTRAIN CONTROL MODULE (Continued)
• Speed Control Relay
• Speed Control Vent Relay
• Speed Control Vacuum Relay
• Transmission Autostick Display (To Cluster)
• Transmission Control Relay
• Transmission PRNDL Position (To Cluster)
• Transmission Solenoids (L/R, 2/4, OD and UD)
• Transmission Torque Reduction Request (Inter-
nal to PCM)
• Transmission Temperature (Internal to PCM)
• Vehicle Speed (Internal to PCM)
• 5 Volt Output
Based on inputs it receives, the powertrain control
module (PCM) adjusts fuel injector pulse width, idle
speed, ignition timing, and canister purge operation.
The PCM also determines the appropriate transmis-
sion shift schedule and shift points, depending on the
present operating conditions and driver demand. The
PCM regulates the cooling fans, air conditioning and
speed control systems. The PCM changes generator
charge rate by adjusting the generator field.
The PCM adjusts injector pulse width (air-fuel
ratio) based on the following inputs.
• Battery Voltage
• Intake Air Temperature Sensor
• EGR valve position (if equipped)
• Engine Coolant Temperature
• Engine Speed (crankshaft position sensor)
• EVAP Purge Valve Postition
• Exhaust Gas Oxygen Content (heated oxygen
sensors)
• Manifold Absolute Pressure
• Throttle Position
The PCM adjusts engine idle speed through the
idle air control motor based on the following inputs:
• Brake Switch
• Engine Coolant Temperature
• Engine Speed (crankshaft position sensor)
• Park/Neutral (transmission gear selection)
• Transaxle Gear Engagement
• Throttle Position
• Vehicle Speed (from Transmission)
The PCM adjusts ignition timing based on the fol-
lowing inputs.
• Intake Air Temperature
• Engine Coolant Temperature
• Engine Speed (crankshaft position sensor)
• Knock Sensor
• Manifold Absolute Pressure
• Park/Neutral (transmission gear selection)
• Transaxle Gear Engagement
• Throttle Position
In addition to monitoring inputs and controlling
outputs, the PCM has other important transmission
related responsibilities and functions:
ELECTRONIC CONTROL MODULES 8E - 9
• Storing and maintaining Clutch Volume Indices
(CVI)
• Storing and selecting appropriate Shift Sched-
ules
• System self-diagnostics
• Diagnostic capabilities (with DRB III scan tool)
The automatic shut down (ASD) and fuel pump
relays are mounted externally, but turned on and off
by the powertrain control module.
The camshaft and crankshaft signals are sent to
the powertrain control module. If the PCM does not
receive both signals within approximately two second
of engine cranking, it deactivates the ASD and fuel
pump relays. When these relays are deactivated,
power is shut off to the fuel injectors, ignition coils,
fuel pump and the heating element in each oxygen
sensor.
The PCM contains a voltage converter that
changes battery voltage to a regulated 5.0 volts. The
5.0 volts power the camshaft position sensor, crank-
shaft position sensor, vehicle speed sensor, engine
coolant temperature sensor, intake air temperature
sensor, manifold absolute pressure sensor, and throt-
tle position sensor.
The PCM engine control strategy prevents reduced
idle speeds until after the engine operates for 320 km
(200 miles). If the PCM is replaced after 320 km (200
miles) of usage, update the mileage in new PCM. Use
the DRB scan tool to change the mileage in the PCM.
Refer to the appropriate Powertrain Diagnostic Man-
ual and the DRB scan tool.
TRANSMISSION CONTROL
CLUTCH VOLUME INDEX (CVI)
An important function of the PCM is to monitor
Clutch Volume Index (CVI). CVIs represent the vol-
ume of fluid needed to compress a clutch pack.
The PCM monitors gear ratio changes by monitor-
ing the Input and Output Speed Sensors. The Input,
or Turbine Speed Sensor sends an electrical signal to
the PCM that represents input shaft rpm. The Out-
put Speed Sensor provides the PCM with output
shaft speed information.
By comparing the two inputs, the PCM can deter-
mine transaxle gear position. This is important to
the CVI calculation because the PCM determines
CVIs by monitoring how long it takes for a gear
change to occur (Fig. 6).
Gear ratios can be determined by using the DRB
Scan Tool and reading the Input/Output Speed Sen-
sor values in the "Monitors" display. Gear ratio can
be obtained by dividing the Input Speed Sensor value
by the Output Speed Sensor value.