Powertrain Control Module

WARNING: This page is about a different car, the 2003 Dodge SX and 2003 Dodge Neon. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: The Powertrain Control Module (PCM) and the Transmission Control Module are incorporated into one module. The module is the Next Generation Controller (NGC) and will be referred to throughout this article as the PCM.

The Powertrain Control Module (PCM) is located in the engine compartment. See Fig 1 or Fig 2 . The PCM is a digital computer containing a microprocessor. The PCM receives input signals from various switches and sensors referred to as PCM inputs. Based on these inputs, the PCM adjusts various engine and vehicle operations through devices referred to as PCM outputs. See INPUT DEVICES and OUTPUT SIGNALS .

Fig 1: Locating Powertrain Control Module (2.0L)

Courtesy of CHRYSLER CORP.

Fig 2: Locating Powertrain Control Module (2.4L)

Courtesy of DAIMLERCHRYSLER CORPORATION

Based on inputs the PCM receives, the PCM adjusts fuel injector pulse width, idle speed, ignition timing and canister purge operation. The PCM regulates the cooling fans, A/C 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
Inlet Air/Intake Air Temperature Sensor
Engine Coolant Temperature
Engine Speed (Crankshaft Position Sensor)
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.

Air Conditioning Sense
Battery Voltage
Battery Temperature
Brake Switch
Engine Coolant Temperature
Engine Speed (Crankshaft Position Sensor)
Engine Run Time
Manifold Absolute Pressure
Power Steering Pressure Switch
Transmission Gear Selection (Park/Neutral Switch)
Throttle Position
Vehicle Distance (Speed)

The PCM adjusts ignition timing based on the following inputs.

Engine Coolant Temperature
Inlet Air/Intake Air Temperature
Engine Speed (Crankshaft Position Sensor)
Knock Sensor
Manifold Absolute Pressure
Throttle Position
Transmission Gear Selection (Park/Neutral Switch)

The Auto Shutdown (ASD) and fuel pump relays are located in the Power Distribution Center (PDC). The camshaft position sensor and crankshaft position sensor signals are sent to the PCM. If the PCM does not receive the signal within approximately 1 second of engine cranking, it deactivates the ASD relay and fuel pump relay. When these relays are deactivated, power is shut off from the fuel injectors, ignition coils, oxygen sensor heating elements and fuel pump. The PCM contains a voltage converter that changes battery voltage to a regulated 5 volts direct current to power the camshaft position sensor, crankshaft position sensor, manifold absolute pressure sensor, throttle position sensor, A/C pressure switch, A/C pressure transducer, and vehicle speed sensor.

The PCM contains a self-diagnostic system which stores a Diagnostic Trouble Code (DTC) if an electronic control system failure exists. DTC may be retrieved from PCM for system diagnosis by using a scan tool. See SELF-DIAGNOSTIC SYSTEM .