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ACRONYMS AND DEFINITIONS

NOTE : This Acronyms and Definitions listing contains technical terms applicable to Ford Motor Company products. It is not intended to be an all-inclusive dictionary of components and their functions. If a detailed description of a particular system or component is desired, refer to the applicable Vehicle System for the specific vehicle being serviced.

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 perform 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 : Norm ally 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.

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.

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 Multi port 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

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.

Zip Tube : Another name for "fresh air duct" or "air inlet duct".

TRANSMISSIONS :

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 Ax45 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.


  • S91/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 Transmission Control Switch (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.