Chrysler Concorde/Intrepid/LHS/New Yorker/Vision 1993-1997

General Information


See Figure 1

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Fig. Fig. 1: Some of the input and outputs of the PCM

The engine computer, which controls the fuel injection system on the vehicles covered by this guide, is referred to as the Powertrain Control Module (PCM). The PCM is a digital computer containing a microprocessor. The PCM receives input signals from various switches and sensors that are referred to as engine computer inputs. Based on these inputs, the PCM adjusts various engine and vehicle operations through devices referred to as outputs.

The PCM inputs are as follows:

Air conditioning controls
Battery voltage
Brake switch
Camshaft position sensor
Crankshaft position sensor
Intake Air Temperature (IAT) sensor (3.3L)
Distance sensor
Transaxle Control Module (TCM)
Transaxle gear engagement (From the TCM)
Torque management input (From the TCM)
Engine Coolant Temperature (ECT) sensor
Knock Sensor (3.5L)
Manifold Absolute Pressure (MAP) sensor
Heated oxygen sensors
Ignition sense
Throttle Position Sensor (TPS)
Park/Neutral switch
SCI receive
Speed control
Vehicle Speed Sensor (VSS)

The PCM outputs are as follows:

Air conditioning clutch relay
Alternator field
Idle Air Control (IAC) Motor
Auto Shutdown (ASD) and fuel pump relays
EGR solenoid
Duty cycle EVAP purge solenoid
Data link connector (CCD and SCI Transmit)
Electric EGR Transducer (EET)
Fuel injectors
Alternator field
High speed fan relay
Ignition coils
MTV solenoid
Speed control relay
Speed control vent relay
Speed control vacuum relay

Based on inputs it receives, the PCM adjusts fuel injector pulse width, idle speed, ignition timing and canister purge operation. The PCM regulates the cooling fans, air conditioning and speed control systems. The PCM changes the alternator charge rate by adjusting the generator field.

The ASD relay and fuel pump relay are mounted externally, but turned on and off by the PCM. The camshaft and crankshaft signals are sent to the PCM. If the PCM does not receive both signals within approximately one second of engine cranking, it deactivates the ASD and fuel pump relays. When these relays are deactivated, the power is shut off to the fuel injectors, ignition coils, fuel pump and heating element in each oxygen sensor.

The PCM contains a voltage converter that changes battery voltage to a regulated 8.0 volts. The 8.0 volts power the camshaft position sensor, crankshaft position sensor and vehicle speed sensor. The PCM also provides a 5.0 volt supply for the coolant temperature sensor, intake air temperature sensor and throttle position sensor.