Powertrain Control Module

Powertrain Control Module
The center of the Electronic Control (EC) system is a microprocessor called the Powertrain Control Module (PCM). The PCM has a Transmission Control Module (TCM) internal to the PCM for automatic transmission equipped vehicles. The PCM has three electrical connectors (122 pins). The PCM receives input from sensors and other electronic components (switches, relays, etc.) and places this information is RAM or Keep Alive RAM. Based on information programmed into its memory (ROM), the PCM generates output signals to control various relays, solenoids and actuators. For vehicles equipped with manual transmissions, only two plugs are used.

The TCM controls the Power Monitor Strategy. The Power Monitor monitors engine speed at idle. If an abnormal engine speed increase is detected, the Power Monitor will command the Fuel Injection 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. DTCs will be stored if the Power Monitor is active.