Powertrain Management: Description and Operation

PURPOSE
Computerized Engine Control (CEC) Systems electronically regulate the air/fuel mixture, idle speed and ignition timing to achieve optimum[1] engine performance.

INFORMATION STRUCTURE
Information in this section is divided into the following four major sub-headings:

COMPUTERS AND
CONTROL SYSTEMS Addresses the on-board computer system and components as related to engine management. Consult this section for information regarding on-board diagnostics, sensor inputs, computer outputs, transmission controls, etc.

NOTE: Transmission related diagnostic codes and controls are generated and controlled by the Powertrain Control Module (PCM) and are therefore included in this section.

EMISSION CONTROL
DEVICES Addresses emission related systems and components only. Includes (but is not limited to) Exhaust Gas Recirculation (EGR) systems, Evaporative Emission (EVAP) systems, Positive Crankcase Ventilation (PCV) systems, Exhaust Emission controls, Air Injection Systems (AIS), etc.


FUEL SUPPLY AND
AIR INDUCTION
SYSTEMS Focuses on systems and components related to fuel and intake air delivery. Does NOT include information regarding electronic engine controls.

IGNITION SYSTEM Focuses on primary and secondary ignition systems and components. Does NOT include information regarding electronic engine controls.



[1] Optimum performance means the best possible compromise between the demands of high power, low fuel consumption, and the cleanest possible exhaust emissions.


ABBREVIATIONS:


ALDL Assembly Line Data Link
BCM Body Computer Module
CCC Climate Control Center
CTS Coolant Temperature Sensor
DERM Diagnostic Energy Reserve Module (part of SIR)
ECC Electronic Climate Control
ECM Engine Control Module (now referred to as PCM)
EST Electronic Spark Timing
HEI High Energy Ignition
IAC Idle Air Control
IPC Instrument Panel Cluster
ISC Idle Speed Control Motor
MAP Manifold Air Pressure
MAT Manifold Air Temperature
PCM Powertrain Control Module (Previously called ECM)
SIR Supplemental Inflatable Restraint
TPS Throttle Position Sensor
VCC Viscous Converter Clutch
VSS Vehicle Speed Sensor