Powertrain Control Module (PCM)

The center of the electronic engine control (EEC) system is the PCM. The PCM contains both engine and transmission microprocessors. Operating information, as well as concern information, is communicated between the 2 processors through controller area network (CAN) communications. Both can be programmed individually, however, a new PCM is installed as an assembly. The PCM has 3 electrical connectors (122 pins total). The PCM receives input from sensors and other electronic components (switches and relays) and places this information into random access memory (RAM) or keep alive memory (KAM). Based on information programmed into its read-only memory (ROM), the PCM generates output signals to control various relays, solenoids, and actuators. For vehicles equipped with manual transmissions, only 2 electrical connectors are used.

The transmission control module (TCM) controls the power monitor strategy. The power monitor monitors the engine speed at idle. If an abnormal engine speed increase is detected, the power monitor commands the fuel injector control module (FICM) off in an effort to maintain a normal idle speed. For manual transmission vehicles, the power monitor is the only active TCM function. Diagnostic trouble codes (DTCs) are stored if the power monitor is active.