Aspire L4-81 1.3L SOHC (1994)
Powertrain Control Module: Description and Operation
Powertrain Control Module
PURPOSE
The Powertrain Control Module (PCM) is a vital part of the Electronic Engine Control (EEC).
The PCM receives input signals from a series of sensors, makes computations based on these inputs, and sends signals to the various outputs to
control many functions, including: air/fuel mixture, ignition timing, evaporative emissions and Exhaust Gas Recirculation (EGR) control.
OPERATION
The PCM sends out a regulated, 5 volt reference voltage (VREF) to the input sensors. These sensors require a constant VREF source to provide
an accurate signal. The PCM monitors the signals from these sensors and calculates the proper operating strategy for the engine operating
conditions.
CONSTRUCTION
The PCM's calibration assembly contains the necessary programming to fine-tune the PCM's engine calibration commands to each vehicle's
weight, axle ratio, and transmission application. The calibration assembly is an integral part of the PCM and is not replaceable.
