B350 1 Ton Van V6-239 3.9L (1990)
Powertrain Control Module: Description and Operation
General Operation
Computerized Engine Controls
The engine systems in this vehicle are controlled by a Single Board Engine Controller (SBEC). This controller provides precise air/fuel mixture control
for all driving conditions, and regulates ignition timing, emission control devices, cooling fan, charging system, and idle speed. The SBEC is a digital
pre-programmed computer that has the ability to update and revise its programming to meet changing operating conditions.
Various sensors provide necessary input for the SBEC to function correctly. These include the Manifold Absolute Pressure Sensor, Throttle Position
Sensor, Oxygen Sensor, Coolant Temperature Sensor, and Vehicle Distance Sensors. In addition to these sensors, various switches and relays are used
to carry out commands or outputs from the SBEC.
The SBEC tests many of its own input and output circuits. If a fault is found in any major system, this information is either stored in memory or
displayed as a light on the instrument panel. If a fault exists, the fault information can be displayed to a technician through the instrument panel CHECK
ENGINE lamp or a suitable diagnostic scan tool. For diagnosis and repair information for Computerized Engine Controls see COMPUTERIZED
ENGINE CONTROLS.
