Powertrain Control Module (PCM)

The PCM is a microprocessor based computer that is the main component of the powertrain control system.

Identification:
There are four different versions of the PCM:
1. SOHC multi-port injection with manual transaxle.
2. SOHC multi-port injection with automatic transaxle.
3. DOHC multi-port fuel injection with manual transaxle.
4. DOHC multi-port fuel injection with automatic transaxle.

Construction:
Each powertrain control module (PCM) contains either one or two separate controllers located in one assembly. Manual transaxle versions contain only the engine controller (EC), the automatic transaxle versions contain an engine controller (EC) and a transaxle controller (TC).

Quad Drivers:
The powertrain control module (PCM) controls some components with electronic switches which complete a ground circuit when turned On. These switches are arranged in groups of four called quad driver modules (QDM's). The QDM can independently control the four output circuits. Not all outputs are always used. Fault detection logic inside the QDM compares driver input and output voltages.

Operation:
The powertrain control module (PCM) uses signals from various sensors in order to optimize the control of the engine, transaxle, and electrical variable orifice power steering system. The subsystem also provides information to other subsystems and to service equipment.