IAC: Idle Air Control. Electrical control of throttle bypass air.
IAT: Intake Air Temperature.
IATV: Intake Air Temperature Voltage. Actual voltage drop across the IAT sensor.
IAT2: Intake Air Temperature 2. Displayed in either Fahrenheit or Centigrade. Used on supercharged vehicles.
IAT2V: Intake Air Temperature 2 Voltage. Actual voltage drop across the IATV2 sensor.
IC: Integrated Circuit. A small semi—conductor device capable of doing many separate circuit functions.
ICM: Ignition Control Module. The module that controls the ignition system.
IFDM: Integrated Fuel Delivery Module.
IFS: Inertia Fuel Shutoff.
IGN GND: Ignition Ground.
Ignition: System used to provide high voltage spark for internal combustion engines.
IGN_KEY (IGKY): Ignition Key status.
IGN_SW (IGSW): Ignition Switch Position.
IMRC: Intake Manifold Runner Control. Controls airflow through the high—speed runners in the intake manifold.
IMRCM: Intake Manifold Runner Control Monitor. Monitors the IMRC / circuits for faults.
IMTV: Intake Manifold Tuning Valve. Controls airflow through runners in a split intake manifold.
INJ1, INJ2, INJ3, INJ4, INJ5, INJ6, INJ7, INJ8, INJ9, INJ10: Injector number or its signal output from the PCM.
Injector: A device for delivering metered pressurized fuel to the intake system or the cylinders.
Intake Air: Air drawn through a filter and distributed to each cylinder for use in combustion.
Intercooler: See CAC.
IPATS: Integrated Passive Anti—Theft System.
ISO: International Standards Organization.
KAM: Keep Alive Memory. A portion of the memory within the PCM that must have power even when the vehicle is not operating.
KAPWR: Keep Alive Power. Dedicated, unswitched power circuit that maintains KAM.
Key On
Engine Off Self—Test: A test of the EEC system conducted by the PCM with power applied and the
engine at rest.
Key On
Engine Running Self—Test: A test of the EEC system conducted by the PCM with the
engine running and the vehicle at rest.
KEYPWR: Key Power. Battery voltage supplied when the ignition key is in the ON position.
Knock: The sharp metallic sound produced when two combustion pressure fronts collide in the combustion chamber of an engine.
KOEC: Key On
Engine Continuous.
KOEO: Key On
Engine Off.
KOER: Key On
Engine Running.
KPA: Kilopascal. Unit of pressure. 3.386 kPa = 1 inch of mercury (Hg.).
KPH: Kilometers Per Hour.
KS: Knock Sensor. Detects
engine knock.
L: Liters. The unit of volume in the metric measuring system. One liter equals 1.06 quarts.
LEV: Low Emissions Vehicle.
LFC: Low Fan Control.
LFP: Low Fuel Pump. Reduced operating speed for multi—speed fuel pumps.
LIFO: Last In First Out.
LILO: Last In Last Out.
LONGFT1, LONGFT2: Long—Term Fuel Trim. Fuel flow adjustment determined by the PCM.
LOOP: Indicates OPEN or CLOSED loop status.
LPG: Liquefied Petroleum Gas.
LPLR: Low Pressure Low Resistance fuel injector.
M—85: Fuel containing 85% methanol alcohol.
MAF: Mass Air Flow. Used to measure the mass (weight) of the air entering the engine.
MAF RTN: Mass Air Flow Return. A return circuit for the MAF sensor.
MAP: Manifold Absolute Pressure. The internal pressure of the intake manifold.
MFC: Medium Fan Control.
MFI: Multiport Fuel Injection. A fuel—delivery system in which each cylinder is individually fueled.
MFP: Modulated Fuel Pump.
Microprocessor: A digital processor on a chip which performs arithmetic and control logic.
MIL: Malfunction Indicator Lamp. An indicator lamp alerting the driver of an
emission related malfunction. May also read "CHECK ENGINE" or "SERVICE
ENGINE SOON."
MISF: Misfire. Any event in the cylinder that causes a sudden change in acceleration of the crankshaft.
MON: Motor Octane Number.
Monolithic Substrate: The ceramic honeycomb structure used in the
catalytic converter.
MSOF: Manual Shift—on—the—Fly.
MY: Model Year.
NA: Naturally Aspirated.
Engine that is not supercharged or turbocharged.
NAAO: North American Automotive Operations.
NC: Normally Closed.
NG: Natural Gas. A system capable of using natural gas for vehicle operation.
NGS: New Generation STAR (Self—Test Automatic Readout) tester.
NGVM: Natural Gas Vehicle Module.
NO: Normally Open.
NO X : Oxides of Nitrogen. Formed at high combustion temperatures.
NVH: Noise, Vibration, Harshness. A classification of vehicle concerns.
OASIS: On—line Automotive Service Information System.
OBD, OBD—II: On—Board Diagnostics, On—Board Diagnostics Second Generation. A system that monitors PCM input and output control signals.
On—Demand Test: Technician initiated "KOEO" and "KOER" tests performed by the PCM.
OC: Oxidation
Catalytic converter. A
catalytic converter system that reduces levels of HC and CO.
OCT ADJ: Octane Adjust. Compensating strategy that adjusts for changes in fuel octane.
OEM: Original Equipment Manufacturer.
OHC: OverHead Cam. An
engine configuration that uses a single camshaft positioned above the valves.
OWL: Overheat Warning Lamp or its signal output from the PCM. Turns the TEMP warning lamp ON when
engine oil temperature exceeds safe limits.
Open Circuit: A circuit which does not provide a complete path for flow of current.
OL: Open Loop. An operating condition based on instructions not modified by PCM feedback.
O 2 S 11/12/21/22: Oxygen Sensor and its relative position in the exhaust system. Detects oxygen content in exhaust gasses.
OSC: Output State Control.
OSS: Output Shaft Speed.
Ozone: A blue gaseous form of oxygen (O 3 ) formed naturally by electric discharge or exposure to ultraviolet radiation.
Particulate: Small solid matter found in exhaust gases, especially prevalent in
diesel engines.
PATS: Passive Anti—Theft System.
PATSIL: Passive Anti—Theft System Indicator Light.
PATSIN: Passive Anti—Theft System Receive Signal.
PATSOUT: Passive Anti—Theft System Transmit Signal.
PATSTRT: Passive Anti—Theft System Starter Relay Control
PCM: Powertrain Control Module. Formerly known as the EEC (Electronic
Engine Control) Processor.
PCV: Positive Crankcase Ventilation. A system which allows the controlled flow of crankcase vapors into the combustion chamber.
PF: Purge Flow. Amount of fuel vapor burned in the engine.
Photochemical: Term describing the action of light on air pollutants which results in creating smog.
PID: Parameter Identifier. Identifies an address in PCM memory which contains operating information.
Powertrain:
Engine and transmission/transaxle components.
Pressure — Absolute: A pressure referenced to a perfect vacuum.
Pressure — Atmospheric: The pressure of the surrounding air at any given temperature and altitude. Sometimes called Barometric Pressure.
Pressure — Barometric: Pertaining to atmospheric pressure or the results obtained by a barometer.
Pressure — Differential: The pressure difference between two regions, such as between the intake manifold and atmospheric pressure.
Pressure — Gage: The amount by which absolute pressure exceeds the ambient atmospheric pressure.
PIP: Profile Ignition Pickup. Provides crankshaft position information for ignition synchronization.
Potentiometer: An adjustable resistance component commonly used as a sensor (Example: TP Sensor).
PPM:
Parts Per Million. A measure used in
emission analysis.
PROM: Programmable Read—Only Memory. Similar to ROM except without program instructions.
Protocol: A set of rules for the exchange of information on a network.
PSOM: Programmable Speedometer/Odometer Module. A module that processes vehicle speed information.
PSP: Power Steering Pressure. Indicates the pressure in the power steering system.
PSP V: Power Steering Pressure Input Voltage.
PTEC: PowerTrain Electronic Controller.
PTO: Power Take—Off.
PW: Pulse Width. The length of time an actuator, such as a fuel injector, remains energized.
PWM: Pulse Width Modulation. Controls the intensity of an output by varying the signal duty cycle.
PWR GND: Power Ground. The main ground circuit in the EEC system.