Continued from: See: 2V-H

• 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.
• NOX: 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.
• O2S 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 (O3) 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.
• Quick Test: A series of diagnostic tests of the EEC system consisting of KOEO, KOER and Continuous Memory Self-Tests. Results are displayed as a series of DTCs.
• RABS: Rear Antilock Brake System.
• RAM: Random Access Memory. Memory into which information can be written as well as read.
• REDOX: Reduction Oxidation Catalytic converter. A catalytic converter system designed to operate at high temperatures.
• Regulator: Controls the alternator/generator field current to maintain proper battery charge. Contained within the PCM in smart charging applications.
• Relay: An electromechanical device in which connections in one circuit are opened or closed by changes in another circuit.
• REM: Rear Electronic Module.
• Repetitive Spark: Multiple firings of individual spark plugs at engine speeds below 1000 RPM to improve idle quality and improve emissions.
• RF: Radio Frequency.
• RFI: Radio Frequency Interference.
• RFS: Returnless Fuel System.
• RM: Relay Module. A module containing two or more relays.
• ROM: Read-Only Memory. Computer memory that can be accessed and utilized, but not altered.
• RON: Research Octane Number.
• Routine: A group of related tasks, such as a series of diagnostic tests.
• RPM: Revolutions Per Minute.
• RS: Reverse Switch.
• RTN: Return. A dedicated sensor ground circuit.
• RWD: Rear Wheel Drive.
• SAE: Society of Automotive Engineers.
• SBS: Supercharger Bypass Solenoid or its signal output from the PCM.
• SC: Supercharged or Supercharger.
• SCB: Supercharger Bypass Control. A system that allows manifold vacuum to be bled away from the supercharger wastegate actuator to allow for maximum boost.
• SCBF: Supercharger Bypass Control Fault. Identifies whether a fault exists in the Supercharger Bypass circuit.
• SCICP: Supercharger Intercooler Pump Control.
• SCICPF: Supercharger Intercooler Pump Control Fault.
• SCIPC: The PID to monitor the operation of the Supercharger and Charge Air Cooler pump.
• SCP: Standard Corporate Protocol.
• Self-Test: See Quick Test. See: Computers and Control Systems\Testing and Inspection\Pinpoint Tests\QT: Step 1: PCM Quick Test
• Sensor: A device that detects the value or change in a physical quantity, such as temperature, pressure or flow rate, and converts the data into an electrical signal.
• SFI: Sequential Multiport Fuel Injection. A multiport fuel delivery system where each injector is individually energized and timed relative to its cylinder intake event.
• Shield: A conducting sleeve that surrounds wires to be electronically isolated from electromagnetic interference (EMI).
• Short Circuit: An undesirable condition in a circuit where it is terminated at a point other than that intended.
• SHRT FT: Short-Term Fuel Trim. Fuel flow adjustment in response to the HO2S sensor(s) input during closed-loop operation.
• SIG RTN: Signal Return. A dedicated sensor ground circuit that is common to two or more sensors.
• SIL: Shift Indicator Lamp.
• Smart Driver: A PCM or ECU output driver that can detect faults (open or shorts) on its output circuit.
• SME: Society of Manufacturing Engineers.
• SOF: Shift-On-the-Fly.
• SOHC: Single Overhead Cam.
• Solenoid: A device consisting of an electrical coil which produces a magnetic field in a plunger and pulled to a central position.
• ST: Scan Tool. A device that interfaces with and communicates information on a data link.
• Stoichiometry: An air/fuel mixture that is neither too rich nor too lean. Stoichiometric ratio is 14.7 parts of air for every 1 part of fuel.
• Switch: A device for making, breaking, or changing the connections in an electrical circuit.
• TA: Traction Assist.
• TACH: Tachometer.
• TB: Throttle Body. A device that controls airflow through the engine via a butterfly valve, and has an air bypass channel around the throttle plate.
• TC: 1. Traction Control. Combines anti-lock braking and axle torque reduction to control wheel slippage. 2. Turbocharger.
• TDC: Top Dead Center.
• Tear Tag: The two-piece adhesive label attached to the PCM to identify its calibration.
• Thermistor: A temperature dependent resistor, like that used in CHT and ECT sensors.
• Timing: Relationship between spark plug firing and piston position expressed in crankshaft degrees before (BTDC) or after (ATDC) top dead center of the compression stroke.
• TMAP: Thermal Manifold Absolute Pressure Sensor. A MAP Sensor that includes a thermistor to measure intake air temperature.
• TP: Throttle Position (sensor). A three-wire potentiometer that provides throttle angle and rate information for the PCM.
• TP V: Throttle Position Sensor Voltage.
• Transducer: A device that receives energy from one medium and transfers it to another. For example, thermal energy is converted to an electrical signal through a temperature probe.
• Transmissions/Transaxles: Note: All related items are grouped under the general heading "TRANSMISSIONS" located at the end.
• TSB: Technical Service Bulletin. Notifies service personnel of any known vehicle concerns, procedures, or general service information.
• Underspeed Mode: A control mode that prevents the engine from stalling in the event it stumbles while running. Also used during engine crank.
• Vacuum: Manifold pressure that is reduced below the ambient atmospheric pressure.
• Variable Reluctance: A process of passing a varying magnetic field through wire windings and inducing a voltage.
• VCT: Variable Camshaft Timing.
• VECI: Vehicle Emission Control Information label.
• VIN: Vehicle Identification Number. A unique identification number given to every vehicle produced. Includes information about the year, model, engine, and plant origin of the vehicle.
• VMV: Vapor Management Valve. Controls the flow of fuel vapors out of the carbon canister.
• VOM: Volt-Ohm Meter. Readings are indicated by sweep hand on a printed scale rather than a digital (DVOM) display.
• VPWR: Vehicle Power. A switched circuit that provides power to the EEC system. Compare "Battery Voltage (B+)."
• VREF: Reference Voltage. A dedicated circuit that provides approximately a 5.0 volt signal used as a reference by certain sensors.
• WAC: Wide Open Throttle A/C Cut-Off. Turns A/C system off during wide open throttle or certain other operating conditions.
• Wastegate Control: A device that opens the wastegate in case of overboost from a turbocharger.
• WOT: Wide Open Throttle. A condition of maximum airflow through the throttle body.

• Note: The transmission naming convention is as follows:
• The first character, a number, is the number of forward gears.
• The second character, either the letter "F" or "R," represents front (transaxle) or rear (transmission) wheel drive.
• The next set of characters, a grouping of numbers, represents the design torque capacity of the transmission/transaxle (for example, "27" represents 270ft./lbs. in the 4F27E transaxle).
• The last character, if used, is one of the following:
• "E" for electronic shift
• "N" for non-synchronous shift
• "S" for synchronous shift
• "W" for wide ratio
• 4F27E: Also known as the FN Focus automatic transmission.
• 4F44E: Formerly known as the CD4E.
• 4F46S: Formerly known as the AX4S and regular-duty AXOD-E.
• 4F50N: Formerly known as the AX4N and heavy-duty AXOD-E.
• 4R44E: Formerly known as A4LD for 3.0L applications.
• 4R55E: Formerly known as A4LD for 4.0L applications.
• 4R70W: Formerly known as AOD-E.
• 4R100: Formerly known as E4OD.
• 5R44E: Formerly known as A5LD for 3.0L applications.
• 5R55E: Formerly known as A5LD for 4.0L applications.
• 5R55N: Lincoln LS automatic transmission.
• 5R55W: Wide-ratio truck transmission.
• 4x4L: 4x4 Low.
• A/T: Automatic Transmission.
• CCS: Coast Clutch Solenoid.
• CCSF: Coast Clutch Solenoid Fault. Displays a YES if fault exists.
• EPC: Electronic Pressure Control.
• EPCV: Electronic Pressure Control Volts.
• ESS: Electronic Shift Scheduling.
• HCDSS: High Clutch Drum Speed Sensor. PCM input from the 4R44E and 4R55E.
• M5OD: Manual 5-Speed transmission with overdrive (RWD).
• M/T: Manual Transmission/Transaxle.
• NPS: Neutral Pressure Switch or its signal input to the PCM.
• OCS: Overdrive Cancel Switch.
• OSS: Output Shaft Speed. Indicates rotational speed of the transmission output shaft.
• PNP: Park/Neutral Position switch. Also known as Neutral Drive Switch (NDS), Neutral Gear Switch (NGS), and Transmission Switch Neutral (TSN).
• REVERSE or REV: Transmission Reverse Switch Input.
• SIL: Shift Indicator Lamp. A lamp that indicates the preferred shift points on select manual transmission/transaxle vehicles.
• SS1/SS2/SS3: Shift solenoids. Devices that control the shifting in an automatic transmission.
• TCC: Torque Converter Clutch. When energized, causes a mechanical engagement and disengagement of the Torque Converter Clutch.
• TCIL: Transmission Control Indicator Lamp. Indicates that the TCS has been activated.
• TCS: Transmission Control Switch. Modifies the operation of electronically controlled transmissions.
• Torque converter: A device which by its design multiplies the torque in a fluid coupling between an engine and transmission/transaxle.
• TFT: Transmission Fluid Temperature. Indicates temperature of transmission fluid.
• Transaxle: A device consisting of a transmission and axle drive gears assembled in the same case. Front-wheel drive applications.
• Transmission: A device which selectively increases or decreases the ratio of relative rotation between its input and output shafts. Rear-wheel drive applications.
• TR: Transmission Range. The range in which the transmission is operating.
• TR Sensor: Formerly known as Manual Lever Position Sensor (MLPS). Provides information to the PCM on the transmission range selector position.
• TR V: Transmission Range Voltage.
• TSS: Turbine Shaft Speed. Indicates rotational speed of the transmission turbine shaft.
• VSS: Vehicle Speed Sensor. A magnetic pickup device that generates an AC signal that is proportional to vehicle speed.