S15/T15 Sonoma P/U 2WD V6-262 4.3L VIN W CPI (1994)
Engine Control Module: Description and Operation
Engine Control Module
Fig. 5 ECM Unit (Showing PROM & CALPAK Locations)
Powertrain Control Module (PCM)
PURPOSE
The Powertrain Control Module (PCM) is the control center of the fuel injection system. It constantly looks at the information from various sensors
(inputs) and controls the systems (outputs) that affect vehicle performance. The PCM also performs the diagnostic function of the system. It can
recognize operational problems, alert the driver through the Malfunction Indicator Lamp (MIL) "Service Engine Soon" light on the instrument panel
and store a Diagnostic Trouble Code(s) (DTC) in the PCM memory. The DTC identifies the problem areas to aid the technician in performing repairs.
OPERATION
The PCM is an electronic computer designed to process the various input information, and send the necessary electrical response to control fuel
delivery, spark control, and other emission control systems. The PCM can control these devices through the use of Quad Driver Modules (QDM).
