Engine Control Module: Description and Operation

POWERTRAIN CONTROL MODULE (PCM)

Powertrain Control Module (PCM):

The PCM is secured to a bracket mounted to the front of dash near the right strut tower. The PCM uses one main microprocessor to control the engine and transaxle. The main function of the PCM is to control fuel and spark to the engine and to control transaxle shift points and shift feel. The PCM also controls:
^ A/C relay
^ Cooling fans via a 2-wire logic circuit to the cooling fan control module
^ Cruise control (if equipped) enable
^ Generator L-terminal voltage (needed for charging)

The PCM sends messages to the BCM or I/P cluster over the Class II link to control the:
^ Coolant temp gauge
^ Fuel gauge
^ Change Oil Soon telltale
^ Charge telltale
^ Coolant Temperature telltale
^ Low Fuel telltale
^ Malfunction Indicator Lamp (MIL)
^ Oil Pressure telltale
^ Service telltale
^ Speedometer
^ Tachometer
^ Upshift telltale

The PCM uses inputs from various sensors, processes the information and commands output devices. It performs diagnostics on both input and output circuits that have associated diagnostic trouble codes (DTCs). If a circuit fault exists when certain DTC parameters have been met, a DTC will be set and the PCM will store Freeze Frame/Failure Record information.