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.
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".
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.
- 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.