AAT

Ambient Air Temperature

ABS

Anti-lock Braking System is an automobile safety system that allows the wheels on a motor vehicle to maintain tractive contact with the road surface according to driver inputs while braking, preventing the wheels from locking up (ceasing rotation) and avoiding uncontrolled skidding

AC

Air Conditioning is the process of altering the properties of air (primarily temperature and humidity) to more favorable conditions.

ACC

The accessory position of ignition key or fuse panel that powers accessories like a radio and power windows to operate without having the engine running.

ACP

Audio Control Protocol is the communications protocol for audio and entertainment systems

AC - Alternating Current

Electrical flow of electrons that first flow in one direction in a circuit and then in the opposite direction at regular time intervals.

Active Faults

A fault that is currently out of range or that was out of range the last time the engine was operated

Active Regeneration

The form of regeneration that is used when the soot is collected in the DPF faster than it can be oxidized and is controlled by the engine's ECM. The engine control system commands aftertreatment fuel injection to increase the exhaust temperatures.

AIC

Auxiliary Idle Control is controlling the idle speed of the engine to allow for operation of engine or transmission mounted accessories such as pumps or to increase the output of the charging system to power equipment and prevent excessive discharging of the batteries.

AICM

Auxiliary Idle Control Module, also called Auxiliary Powertrain Control Module (APCM), is for use in Light Trucks equipped with Diesel engines to elevate engine speed for increased power output at idle and to maintain battery charge

Actuator

An output device which delivers motion in response to an electrical signal.

Additive

A compound that enhances some property of, or imparts some new property to, the base fluid. In some hydraulic fluid formulations, the additive volume may constitute as much as 20 percent of the final composition. The more important types of additives include anti-oxidants, anti-wear additives, corrosion inhibitors, viscosity index improvers, and foam suppressants.

Aeration

The state of air being suspended in a liquid such as a lubricant or hydraulic fluid.

Aftercooler

A heat exchanger used to cool compressed induction air from turbocharging or supercharging. It reduces the charged air temperature by transferring heat from the charge air to a cooling medium such as air or coolant.

Aftertreatment

A method of controlling exhaust emissions with the use of a catalyst or, filter installed in the exhaust system.

AJB

Auxiliary Junction Box

Algorithm

Software stored in a module that is used to establish a step-by-step procedure to determine a value based on inputs from engine sensors. This value is used to provide output to various devices on the engine. of interaction with exhaust gas in order to reduce the levels of pollutants emitted.

Alternator

An engine driven power source that supplies electrical force necessary to cause electrical current flow in a circuit.

Ammeter

An instrument used to measure current flow in a circuit.

Ampere

The standard unit of measure for current flow.

Ambient Temperature

The environmental air temperature in which something operates in. Typically it is a measurement of the air temperature in the shade with no solar radiation or wind.

Anaerobic

A substance that will cure or activate with the absence of oxygen. As related to automotive terms, sealants and retaining compounds like threadlockers cure after mating parts have been assembled and are no longer exposed to free oxygen.

Analog

A continuously variable voltage.

API

The American Petroleum Institute is the largest U.S trade association for the oil and natural gas industry. It claims to represent about 400+ corporations involved in production, refinement, distribution, and many other aspects of the petroleum industry.

AP

Accelerator Pedal

APP

Accelerator Pedal Position

APS - Accelerator Position Sensor

Sensor used to determine the relative position of the accelerator pedal.

Ash

The minute amount of particulate matter that is left after oxidation. A diesel particulate filter physically traps and collects diesel soot from engine exhaust which is then burned off through filter regeneration, metal oxide “ash” particles are not burned and are left behind. The particles are the un-burned materials from engine oil additives, fuel additives and metals from engine wear.

A/T

Automatic Transmission

ATF

Automatic Transmission Fluid is the fluid used in vehicles with self shifting or automatic transmissions. It is typically colored red to distinguish it from motor oil and other fluids in the vehicle. The fluid is optimized for the special requirements of a transmission, such as valve operation, brake band friction and the torque converter as well as gear lubrication. ATF is also used as a hydraulic fluid in some power assisted steering systems, as a lubricant in some 4WD transfer cases, and in some manual transmissions.

Atom

The building blocks that create all matter. Atoms are made up of three basic particles: protons, neutrons, and electrons.

AWD

All Wheel Drive

AWA Feature

A feature built into the high pressure oil rails used to dampen noises that can be caused by the hydraulic system.

Backbone

The communications harness used for J1939 communication

BARO/BAP - Barometric Absolute Pressure Sensor

A variable capacitance sensor which when supplied with a 5 volt reference signal from the PCM, produced a linear analog voltage signal indicating atmospheric pressure.

BATT

Battery voltage.

Babbitt

An Alloy of tin, copper, and antimony having good anti friction properties used as a facing for bearings.

Backflushing

Pushing fluid in a direction opposite of normal flow. This is done for cleaning the engine's cooling system or fluid coolers and lines.

Backlash

The amount a shaft is allowed to move in a rotational direction or the clearance between the teeth of two gears in mesh.

Backpressure

Pressure against which a fluid or gas is flowing, resulting from friction in lines, restrictions in pipes, valves, pressure in vessel to which fluid is flowing, hydrostatic head, or other impediment that causes resistance to fluid flow.

Banjo Fitting

A type of hydraulic fitting, shaped like a banjo, through which a hollow bolt passes, allowing fluid transfer from a hydraulic line to a hydraulic component

Battery Saver

The battery saver feature is a computer controlled feature that automatically turns off interior lights and come accessories in a parked vehicle after a few minutes to prevent the battery from being drained such as when a door is left ajar.

Bar

A unit of pressure equal to 14.5 psi.

Battery

A device that produces electricity from a chemical reaction. Strictly speaking, a battery consists of two or more cells connected in series or parallel. A common source of Direct Current voltage.

BCM

Body Control Module

BDC - Bottom Dead Center

The lowest position of a piston during the stroke.

Bio-Diesel

The mono alkyl esters of long chain fatty acids derived from renewable lipid feedstocks, such as vegetable oils and animal fats, for use in compression ignition (diesel) engines. Manufactured by transestrification of the organic feedstock by methanol.

Blow-by

The passage of unburned fuel and combustion gases past the piston rings of internal combustion engines, resulting in fuel dilution and contamination of the crankcase oil.

BOO

Brake pedal on/off switch used to send a voltage or signal to electronic modules indicating that the brakes have been applied.

Boost Pressure

1- The pressure of the charge air leaving a turbocharger or supercharger.
2- Inlet manifold pressure that is greater than atmospheric pressure.

Bore

The diameter of an engine cylinder.

BPP

Brake Pedal Posistion

Brake Horsepower (bhp)

The power output from an engine, not the indicated horsepower. The power output of an engine, sometimes called flywheel horsepower is less than the indicated horsepower by the amount of friction horsepower consumed in the engine.

Brake Horsepower (bhp) Net

Net brake horsepower is measured with all engine components. The power of an engine when configured as a fully equipped engine.

BSI

Brake Shift Interlock - is an electro-mechanical interlock that prevents a vehicle's transmission from being shifted from the park position without the brakes being applied.

BTDC

Before Top Dead Center

BTU - British thermal unit

The amount of heat required to raise the temperature of 1 pound of water 1 degree Fahrenheit

Bypass Filtration

A system of filtration in which only a portion of the total flow of a circulating fluid system passes through a filter at any instant or in which a filter having its own circulating pump operates in parallel to the main flow.

B5

Diesel fuel that is 95% petroleum diesel with 5% biodiesel blended in.

B20

Diesel fuel that is 80% petroleum diesel with 20% biodiesel blended in.

B100

Pure biodiesel fuel that is not blended with petroleum diesel.

Cackle

A noise above the normal sound of combustion that may sound like a rod knock, but is intermittent and increases in intensity as the engine warms up to operating temperature. This noise is may be caused by a pressure variation within the fuel rail causing incomplete fuel fill in a fuel injector on split-shot injectors. The cackle is usually attributed to cylinder #8

CAC - Charge Air Cooling

A process of cooling the air coming from the turbocharger before it enters the engine

CACT

Charge Air Cooler Temperature

Calibration

The data values used by the strategy to solve equations and make decisions. Calibration values are stored in Read Only Memory and put into the processor during programming to allow the engine to operate within certain parameters

Calibration Oil

Oil which is used in a tester for checking injection nozzles and mechanical injection pumps, meeting SAE J967D specifications

Cam Follower

Also known as a "tappet" or a "lifter" this engine part contacts the lobes on a camshaft to change rotating motion to linear motion. Some cam followers are of solid construction but most modern engines use hydraulic cam followers that contain a hydraulic piston that uses engine oil under pressure to automatically adjust valve lash clearance

Camshaft

A shaft with eccentric lobes used in most internal combustion engines to open and close valves

Canister Style Oil Filter

An oil filter that requires only the element be replaced and not the housing

Capacitor

A device for storing electrical energy.

CAN

Controller Area Network - A communication protocol for data transfer between control modules

CARB

California Air Resources Board

Carbon Dioxide (CO2)

A colorless, odorless, non-toxic gas. It is one of main products of fossil-fuel combustion. Carbon dioxide is a greenhouse gas that contributes to the potential for global warming

Carbon Monoxide (CO)

A colorless, odorless and toxic gas. It blocks the lungs’ ability to obtain oxygen. CO is produced by incomplete combustion of fossil fuels and is a major part of air pollution. Compression ignition (diesel) engines generate significantly lower CO emissions than spark ignited engines

Catalyst

A substance that causes a chemical reaction without undergoing a chemical change itself

Catalytic Converter

An anti-pollution device in the exhaust system that contains a catalyst for chemically converting some pollutants in the exhaust gasses into harmless compounds. (carbon monoxide, oxides of nitrogen and unburned hydrocarbons)

Cavitation

A dynamic condition in a fluid system that forms gas filled bubbles in the fluid

Cavitation Erosion

A material-damaging process which occurs as a result of vaporous cavitation. "Cavitation" refers to the occurrence or formation of gas- or vapor- filled pockets in flowing liquids due to the hydrodynamic generation of low pressure (below atmospheric pressure). This damage results from the hammering action when cavitation bubbles implode in the flow stream. Ultra-high pressures caused by the collapse of the vapor bubbles produce deformation, material failure and, finally, erosion of the surfaces

CCA - Cold Cranking Ampre Rating

A battery rating - The sustained constant current (in ampres) needed to produce a minimum terminal voltage under a load of 7.2 volts per battery after 30 seconds

CCM

Comprehensive Component Monitor

Cetane Number

A measure of ignition quality of diesel fuel. The higher the cetane number the easier the fuel ignites when injected into an engine. Cetane number is determined by an engine test using two reference fuel blends of known cetane numbers. The reference fuels are prepared by blending normal cetane (n-hexadecane), having a value of 100, with heptamethyl nonane, having a value of 15

CF

Cooling Fan

CFM - Cubic Feet per Minute Number

Rate of volumetric flow. Moves one cubic foot of air in one minute’s time.

Charge Air

Dense, pressurized, heated air discharged from a turbocharger or supercharger

CHT

Cylinder Head Temperature

Circuit Breaker

A circuit protection device. Excess current will cause the circuit breaker to trip, the circuit is opened, and current can no longer flow.

CKP Crankshaft Position Sensor

A magnetic pickup sensor that creates a sine wave voltage when the timing wheel on the crankshaft breaks its magnetic field. The CKP determines crankshaft position and speed

Clearance Volume

(of a cylinder) The space in the top of the cylinder into which the piston never intrudes. It is into this clearance volume that the charge air is compressed during an engine's compression stroke.

CL

Closed Loop

Closed Circuit

A complete electrical path through which current can flow.

Closed Crankcase Breather

A ventilation system that recirculates crankcase vapors into the intake air system

Closed Loop Operation

In a system that uses sensors to provide feedback to the PCM, the PCM uses the sensor to continuously monitor variables and adjust to match engine requirements

Cloud Point

The temperature at which the paraffin in diesel fuel begins to form wax crystals making the fuel cloudy or hazy

CMP - Camshaft Position Sensor

A magnetic pickup sensor that creates a sine wave voltage when a peg on the camshaft breaks its magnetic field. The CMP determines which cycle the piston is in (compression or exhaust)

CO

Carbon Monoxide

CO2

Carbon Dioxide

Coefficient of Friction

The number obtained by dividing the friction force resisting motion between two bodies by the normal force pressing the bodies together

Common Rail Injection

A diesel fuel injection system employing a common pressure accumulator, called the rail, which is mounted along the engine block. The rail is fed by a high pressure fuel pump. The injectors, which are fed from the common rail, are activated by solenoid valves. The solenoid valves and the fuel pump are electronically controlled. In the common rail injection system the injection pressure is independent from engine speed and load. Therefore, the injection parameters can be freely controlled. Usually a pilot injection is introduced, which allows for reductions in engine noise and NOx emissions

Compressor -1

The portion of a turbocharger that is driven by the turbine that increases the volume of air being inducted to an engine.

Compressor -2

A pump that reduces the volume of, and increases the pressure of gases.

Compression Ignition

The form of ignition that initiates combustion in a diesel engine. The rapid compression of air within the cylinders generates the heat required to ignite the fuel as it is injected

Compression Ratio

The ratio between the volume of the cylinder and combustion chamber when the piston is at the bottom of its stroke, and the volume of the combustion chamber when the piston is at the top of its stroke

Compression Test

A test that measures the pressure developed in an engine's cylinder when the piston travels from the bottom to the top of it's stroke with the valves in the closed position also known as the compression stroke. This test is done with a pressure gauge installed in the spark plug hole of a gasoline engine or the glowplug hole or sometimes the injector bore of diesel engines using adapters. This test will identify worn or damaged cylinders, pistons and valvetrain components.

COP

Coil On Plug

Conductor

Provides a path for electrons to move between a power source and a load.

Connecting Rod

In a reciprocating piston engine, the connecting rod connects the piston to the crank or crankshaft. Together with the crank, they form a simple mechanism that converts linear motion into rotating motion

Continuous Monitor

A Powertrain Control module function that continuously monitors the inputs and outputs to ensure that readings are within set limits

Controller Area Network - CAN

A J1939 high speed communication link. CAN-1 is a public drive train data link between the vehicle modules and the PCM. CAN-2 is a private link between the PCM and the FICM/IDM

Coolant

A fluid used to remove and transfer heat

CPP

Clutch Pedal Position

CPU

Central Processing Unit

Crankcase

The housing that encloses the crankshaft, connecting rods and pistons. Other parts may also be housed in the crankcase depending on engine configuration

Crankcase Breather

A vent for the crankcase to release excess air pressure due to heat and combustion blow-by

Crankpin

An off-set cylindrical piece on a crankshaft to which a connecting rod is attached

Crankshaft

The part of an engine which translates reciprocating linear piston motion into rotary motion

CRH - Center Rotating Housing

The housing between the exhaust and intake sides of the turbo that houses the turbo shaft that houses the bearings, oiling system, and water-cooling system if equipped

CTO

Clean Tach Output

Current

The flow of electrons flowing through a conductor (AMPS)

Damper

A device that reduces the amplitude of torsional vibration

Data Bus

The wiring which may be one or more circuits that connect the modules in a network to each other and diagnostic equipment

Dataplate

Identifying information for an engine or vehicle.

DBA

Driver Brake Application

DC - Direct Current

The flow of electrons through a circuit that flows in one direction from a source and then back to the source.

DC

Duty Cycle - the percentage of one period in which a signal is active. A period is the time it takes for a signal to complete an on-and-off cycle.

DC/AC Converter

Converts low voltage 12V-DC to High Voltage 110V-AC typically used to supply power for AC Power Points in vehicles

De-aeration

The removal or purging of gases entrapped in coolant or engine oil

Decomposition Tube

The Decomposition Tube has an integrated diesel exhaust fluid diffuser and will be supplied with the Aftertreatment DEF Dosing Valve already mounted on the reactor flange. The tube is designed so that the ammonia in the injected diesel exhaust fluid can decompose and be adequately mixed with the exhaust stream before it reaches the front face of the Aftertreatment SCR Catalyst.

De-aeration Tank / Degas Bottle

A separate tank in the cooling system used for one or more of the following functions:
1- De-aeration
2- Coolant reservoir (fluid expansion or afterboil)
3- Coolant retention
4- Filling
5- Fluid level indication

DEF - Diesel Exhaust Fluid

A urea-based chemical reactant designed specifically for use in SCR systems to reduce NOx emissions

DEF Dosing Unit

The Aftertreatment DEF Dosing Unit is used to properly and precisely meter catalyst reagent (DEF) into the exhaust stream immediately upstream of the catalyst.

DEF Nozzle

The Aftertreatment DEF Nozzle sprays the DEF solution into the exhaust stream.

DEPS

Dual Equal Phase Shifting

Derate

The process of limiting the power output of an engine to prevent damage. There are varying levels of a derate condition ranging from limiting power to preventing the vehicle from moving to engine shut down. This is a PCM strategy.

DFI

Direct Duel Injection - a fuel injection system where fuel is introduced directly into an engine's cylinder with a fuel injector

DFSO

Deceleration Fuel Shut Off

Digital Fuel Injection

A fuel injection system that uses both an open and close signal to control fuel injectors

Dielectric Grease

A silicone based, electrically thermal insulating grease for use on wiring harnesses, bulkhead connectors, spark wires and other electrical connections. Prevents dirt, grease and moisture from contaminating connection and causing open circuits.

Diode

An electrical device that allows current to flow in only one direction. A rectifier.

Displacement

The stroke of the piston multiplied by the area of the cylinder bore multiplied by the number of cylinders in the engine. (Cubic inch - CID or cubic centimeter - CC)

DLC

Data Link Connector - An industry standardized 16-pin connector located below a vehicle's instrument panel that allows a technician to connect diagnostic equipment to perform tests, view data and program modules

DMM

Digital Multimeter

DPF

Diesel Particulate Filter

DOC

Diesel Oxidation Catalyst

Drive-By-Wire

One or more of the primary vehicle systems operate with electronic controls instead of a traditional mechanical linkage. An electronic signal transmits driver input to steering, throttle or brake input to an electronically controlled steering gear, throttle body or brake system

Driver

A transistor within an electronic module that controls power or ground to an actuator circuit

Downpipe

The exhaust pipe that leads from the turbo turbine outlet to the exhaust system under the vehicle

Diesel Particulate Filter (DPF)

An exhaust after treatment device that traps particulate matter, or soot, generated by the combustion process in diesel engines

DPF Differential Pressure Sensor

The Aftertreatment Diesel Particulate Filter Differential Pressure Sensor is used to read the differential and outlet pressure of the diesel particulate filter to determine the "load" state of the filter.

DTC

Diagnostic Trouble Code - Alpha-numeric codes generated by vehicle modules for troubleshooting vehicle operation. The codes may be generic in nature or manufacturer specific and identify a fault with a specific part, circuit or an operating condition.

Dual Timing System

A timing system that uses both a CKP and CMP sensors to determine engine speed and rotational position.

DVOM - Digital Volt Ohm Meter

A meter that uses a digital display to indicate a measured value. Preferred for use on microprocessor systems because a DVOM has a very high internal impedance and will not load down the circuit being measured

ECM - Electronic Control Module

An ECM controls one or more of the electrical subsystems in a vehicle. It receives electronic signals and commands, processes them and controls electrical output devices via a preset program

ECT - Engine Coolant Temperature Sensor

A thermistor style sensor used to indicate engine coolant temperature

EEC

Electronic Engine Control

EEGR

Electronic Engine Control

EEPROM

Electronically Erasable Programmable Read-Only Memory

EGR Cooler

A heat exchanger used to cool exhaust gases before they are returned to the intake air system

EGRV - Exhaust Gas Recirculation Valve

A valve used to control the flow of exhaust gases into the intake manifold

EGRP - Exhaust Gas Recirculation Valve Position Sensor

A potentiometer style sensor that indicates the amount of movement of the EGR valve

EGRT

Exhaust Gas Recirculation Temperature

EGT - Exhaust Gas Temperature

The temperature of the exhaust gasses leaving the engine measured in various points in the exhaust system. Monitoring exhaust temperature at the turbo indicates combustion temperatures. Monitoring exhaust gasses before and after the EGR coolers indicates EGR system operation and efficiency. Monitoring exhaust temperature in the aftertreatment system verifies DOC, DPF and SCR operation and helps prevent excessively high temperatures.

EI

Electronic Ignition

EJB

Engine Junction Box - fuse and relay panel located in the engine compartment

ELD

Electronic Locking Differential

Electron

A basic particle of an atom. Electrons have a negative charge or polarity. The electrons orbit around the nucleus in layers.

Electron Current Flow

Electron movement flowing from the negative terminal of the source, through the conductors to the load, and back to the positive terminal.

EMD

Engine Manufacturer's Diagnostics

EMI

Electromagnetic Interference

Emissions

The various chemical compounds released into the atmosphere after combustion has taken place.

End Play

The amount a shaft can travel in a fore and aft direction.

Engine Derate

A torque reducing feature intended to minimize or prevent engine damage due to a system not functioning properly.

ENOV

Engine Off Natural Vacuum

EOT - Engine Oil Temperature

A thermistor type sensor that indicates engine temperature

EP - Exhaust Pressure

The EP measures exhaust back pressure so that the ECM can control the EGR and turbocharger actuators. It is a three wire variable capacitance sensor. The ECM supplies a 5-volt reference signal which the EP sensor uses to produce a linear analog voltage to indicate pressure

EPA - Environmental Protection Agency

An agency of the United States federal government which was created for the purpose of protecting human health and the environment by writing and enforcing regulations based on laws passed by Congress. One such regulation pertains to exhaust emissions for example.

EPS

Exhaust Phase Shifting

ERFS

Electronic Returnless Fuel System

ESM

EGR System Module

ESN

Engine Serial Number

ESOF

Electronic Shift-on-the-Fly - An electronic four wheel drive shifting system

ESP - Extended Service Plan

A Ford Motor Company Extended warranty and service contract. These contracts are sold by Ford, Lincoln and Mercury dealers

ETB

Electronic Throttle Body

ETBTACM

Electronic Throttle Body Throttle Control Actuator Motor

ETBTPS

Electronic Throttle Body Throttle Position Sensor

ETC

Electronic Throttle Control

EVAP

Evaporative Emission

EVAPCP

Evaporative Emission Canister Purge Valve

EVRT - Electronic Variable Response Turbocharger

The International Truck and Engine Corporation's trademark for its electronically-controlled turbo charger. Contains actuated vanes in the turbine housing that modify the flow characteristics of exhaust gasses through the turbine housing. The net benefit is the ability to provide the appropriate boost pressure for various engine speeds and load conditions. The EVRT lowers emissions and improves fuel economy. It also functions as a backpressure device which assists the EGR system and reduces engine warm up time

Exhaust Gas Recirculation

The process in which exhaust gas is cooled, mixed with fresh intake air and supplied to the combustion chambers in an engine.

E10

Gasoline containing 10% Ethanol

E85

Gasoline containing 85% Ethanol

FAOS

Fore-Aft Oxygen Sensor

Fault Code

A digital code representing a specific type of control system failure or abnormality.

FEAD (belt)

FEAD or Front End Accessory Drive Belt is the drive belt on the front of an engine that drives the accessory equipment like power steering pumps, alternators and A/C compressors. This is also commonly referred to as the "serpentine" belt

FEPS

Flash EEPROM Programming Signal

FFV

Flexible Fuel Vehicle

FICM - Fuel Injection Control Module

An electronic unit which has the primary function of an electronic distributor for the injectors. It also is the power supply for the injectors

Fixed Resistor

A resistor that does not have the ability to have its resistance value changed.

FLI

Fuel Level Input

FMEM

Failure Mode Effects Management - A powertrain control module default operating mode that that allows the engine or transmission to function with limited capacity during a major system malfunction

FP

Fuel Pump

FPDM

Fuel Pump Driver Module

FPM

Fuel Pump Driver Module

FRP Fuel Rail Pressure

The FRP provides a feedback signal to the ECM indicating the fuel pressure at the fuel rail. It is a three wire variable capacitance sensor. The ECM supplies a 5-volt reference signal which the EP sensor uses to produce a linear analog voltage to indicate pressure

FRPT

Fuel Rail Pressure Temperature

FRT

Fuel Rail Temperature

FSS

Fan Speed Sensor

FTP

Fuel Tank Pressure

FTS Fuel Temperature Sensor

The FTS measures fuel temperature at the fuel rail and changes resistance according to changes in temperature. This is a two wire thermistor type sensor - it's internal thermistor forms a voltage divider with a pullup resister inside of the ECM. When the temperature of the fuel decreases, the resistance of the thermistor increases and the signal voltage increases. When the temperature of the fuel increases, the resistance of the thermistor decreases and the signal voltage decreases

Fuel Cooler

A heat exchanger that uses coolant to dissipate heat from the fuel before it is recirculated to the fuel system

Fuse

A circuit protection device. The protective element in the fuse melts. When the metal melts, the circuit is opened, and current can no longer flow.

Fusible Link

A circuit protection device. Works by melting a specific portion of its wiring when current exceeds a certain amperage level, the circuit is opened, and current can no longer flow.

FWD

Front Wheel Drive

Gage

An instrument or device for measuring, indicating or comparing a physical characteristic

GCM

Gateway Control Module

Generator

A power source that supplies electrical force necessary to cause electrical current flow in a circuit.

GEM - Generic Electronic Module

The first body control module found in Ford trucks used to control body and chassis electronic features and tie together multiple systems such as lighting, power windows, power door locks, electronic four wheel drive systems and vehicle security

Glow Plug

A heating element that is mounted into the cylinder head of a diesel engine that heats the air in the combustion chamber and helps ignite fuel during cold starts and to help reduce white smoke emissions

GPL

Glow Plug Lamp also known as the "wait to start" light. Indicates that the glow plugs are energized and the operator should wait for the light to go off before cranking and starting the engine. In most cases the light is operated by a module and separately from the glow plugs themselves which may continue to be energized and cycled after the lamp goes off.

GPR

Glow Plug Relay - an electrical switch used to control the high current power to the glow plugs

Glow Plug Sleeves

Stainless steel sleeves used to protect the glow plugs from coolant

GPCM - Glow Plug Control Module

Module which supplies power to the glow plugs and identifies variation in current flow to the glow plugs. In trucks equipped with SCR systems the GPCM may also control the DEF tank heater

GPM

Grams Per Mile

GPM

Gallons Per Minute

Ground

A common return path for electric current such as a battery negative terminal, engine block, frame or body. A reference point in an electrical circuit used to make electrical measurements with a multimeter.

GTDI

Gasoline Turbocharged Direct Injection

GVWR

Gross Vehicle Weight Rating is the maximum operating weight/mass of a vehicle as specified by the manufacturer including the vehicle's chassis, body, engine, engine fluids, fuel, accessories, driver, passengers and cargo but excluding that of any trailers

H

Hydrogen

Hall Effect Sensor

A hall effect sensor generates a digital on/off signal that indicates engine speed and timing. The signal is created by a switching action caused by the passing of a vane though a positive and negative voltage potential. When the vane is between the potential, a signal is created. When the gap in between the potential is open, no signal is generated. The wider the vane the longer the duty cycle and the shorter the vane the shorter the duty cycle. A single shorter or longer vane can be used to identify position

HC

Hydrocarbon

HDR

High Data RateE

Heat Exchanger

A device which transfers heat through a conducting wall from one fluid to another or from a fluid to air. Examples include radiators, condenser cores, oil coolers, after coolers

Heat Rejection

The process of heat transfer to the engine coolant

HFCM - Horizontal Fuel Conditioning Module

A frame mounted fuel conditioning module that contains an electric fuel pump, primary fuel filter and water separator with a water sensor

Horsepower

A unit that is used to measure the power of engines and motors. One unit of horsepower is equal to the power needed to lift 550 pounds one foot in one second. This unit has been widely replaced by the watt in scientific usage; one horsepower is equal to 745.7 watts.

HO2S

Heated Oxygen Sensor

HPFP (High Pressure Fuel Pump)

A fuel pump that creates and maintains a high pressure fuel supply used on a common rail fuel injection system

HSCAN

High-Speed Control Area Network

Hydrocarbons - Hc

Compounds containing only carbon and hydrogen. Petroleum consists chiefly of hydrocarbons

Hydraulic/Electronic Unit Injector (HEUI)

A type of unit injector actuated by engine oil pressure rather than the camshaft. A very high oil pressure (up to 3,000 psi) is created by a separate oil pump. This high pressure is routed to every injector through a gallery. The engine’s Electronic Control Module varies the pressure in response to engine speed and other parameters

Hydrometer

An instrument for determining either the specific gravity of a liquid or the API gravity

IAT - Intake Air Temperature Sensor

A thermistor style sensor used to indicate air temperature before the charge air cooler

IAT2 - Intake Air Temperature 2 Sensor

A thermistor style sensor used to indicate air temperature - after passing through the charge air cooler

IAC

Idle Air Control

IAT

Intake Air Temperature

IAT2

Intake Air Temperature

Idler Gear

Gear used to transfer motion from a drive gear to a driven gear. Idler gears are typically mounted on a stationary shaft.

In-line Filter

A filter assembly in which the inlet, outlet and filter element axes are in a straight line

I-CAN

Infotainment Controller Area Network

ICP- Injection Control Pressure

A variable capacitance style sensor used to indicate high pressure oil system pressure

IDM - Injector Drive Module

An electric unit which has a primary function of an electronic distributor for the injectors. It also is the power supply for the injectors. It supplies 90 volts at 7 amps to the injectors

IDS - Integrated Diagnostic System

The current modular diagnostic system to support the latest Ford vehicles that uses a PC or laptop , IDS Software, a Vehicle Communication Module (VCM) to interface with vehicle modules, a Vehicle Measurement Module (VMM) to perform specialized electrical tests.

IFS

Inertia Fuel Shutoff

Impedance

A form of opposition to AC current flow measured in Ohms

Impeller

Another name for a turbocharger compressor wheel.

IMRC

Intake Manifold Runner Control

IMTV

Intake Manifold Tuning Valve

Inactive Fault

A historical fault that was out of range at one time but is currently within range

Inhibitor

Any substance that slows or prevents such chemical reactions as corrosion or oxidation

I/0 Injector Test

A test that can be performed using the WDS to disable one injector at a time while watching Mfdes to determine a weak contributing injector

Inputs

Electrical devices, such as sensors and switches, that provide signals that indicate engine operating conditions and switches that provide operator input to determine desired operation.

IPC

Instrument Panel Cluster

IPR - Injection Pressure Regulator

Controls injection oil pressure. An electrical signal to a solenoid creates a magnetic field which applies a variable force on a poppet to control pressure. The quantity of fuel delivered to the combustion chamber is proportional to injection control pressure

IPS

Intake Phase Shifting

ISO

International Standards Organization (9140 protocol)

IVS - Idle Validation Switch

An on/off switch that indicates when the accelerator pedal is in the idle position

J1587

An SAE software communications standard

J1708

An SAE hardware communications standard

J1850

A network protocol also referred to as Standard Corporate Protocol or SCP

J1939

An SAE hardware and software communications standard

Journal

Part of a shaft or axle in contact with, or enclosed by, a bearing.

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

A dedicated and unswitched power circuit that maintains KAM

kiloPascal

A unit of pressure equal to approximately 0.145 psi

Kilowatt - kW

One thousand watts.

km/h

Kilometers Per Hour

KOEO - Key On Engine Off Self Test

A self-test operation that is performed with the ignition switch in the ON position with the engine OFF

KOER - Key On Engine Running Self Test

A self-test operation that is performed with the ignition switch in the ON position and the engine RUNNING

kPa

Kilopascal

KPWR

Battery voltage that is received indicating that the ignition switch is in the ON position

KS

Knock Sensor

lb-ft

Pounds of force per foot

lb-in

Pounds of force per inch

LDR

Low Data Rate

LED - Light Emitting Diode

An electronic device that emits light when an electrical current is passed through it. LEDs are commonly used for indicator lights.

Liner Protrusion

The measured amount a cylinder liner protrudes above the deck of an engine block.

Load

Converts the energy of the moving electrons to a more useful form such as movement, heat or light.

Lubricant

Any substance interposed between two surfaces in relative motion for the purpose of reducing the friction and/or the wear between them

Lubricity

The ability of an oil, fluid or grease to lubricate; also called film strength

LONGFT1, LONGFT2 = Long-Term Fuel Trim

Fuel flow adjustment determined by the PCM

LOOP

Indicates OPEN or CLOSED loop status

LSD - Low Sulfur Diesel

Low sulfur diesel is diesel fuel that has been refined so that its sulfur content is 500 parts per million (ppm) or less.

MAF

Mass Airflow

Main Power Relays

Battery power relay switches for the PCM and FICM (modules) that are key power initiated and controlled by the corresponding powered module

MAP - Manifold Absolute Pressure Sensor

A MAP sensor generates a digital frequency that indicates manifold boost pressure above atmospheric pressure. The signal is created by switching action caused by manifold pressure of a diaphragm connected to a capacitor circuit in the sensor. The digital frequency increases as pressure increases. A MAP sensor has three connection: signal return(gnd), MAP signal, and VREF

mB - milliBar

One milliBar equals .001 Bar

MFF

Misfire Freeze Frame

MGP - Manifold Gauge Pressure

Manifold pressure reading equal to the manifold absolute pressure reading (MAP) minus the barometric pressure (BARO) reading. This is commonly used as or referred to as the "boost" measurement.

Micron

Measurement that equals one millionth of a meter.

MIL

Malfunction Indicator Lamp

Misfire Detection

Uses engine RPM changes during a firing cycle to determine a low contributing cylinder

Modular Water Pump

Is a water pump that uses the front cover as a housing and only the hub and impeller are replaceable

MPH

Miles Per Hour

MRFS

Mechanical Returnless Fuel System

MSOF

Manual Shift On-The-Fly

M/T

Manual Transmission

Multiplexing

A method by which multiple digital data streams are combined into one signal over a shared network of modules. This strategy allows control modules to communicate during normal vehicle operation.

NA - Naturally Aspirated

An engine that is not supercharged or turbocharged. Air is induced by the force of natural air pressure

Network

The control modules and wiring that allow data to be sent or received. A network may be directly wired or wireless.

Neutron

A basic particle of an atom, neutrons have no charge or polarity and they bond with protons to form the nucleus.

Normally Closed

Refers to a switch or a solenoid that is closed when no control or force is acting on it

NH3

Ammonia

Normally Open

Refers to a switch or a solenoid that is open when no control or force is acting on it

NOx - Nitrogen Oxides

Sometimes referred to as "Oxides of Nitrogen" a generic term for mono-nitrogen oxides NO and NO2 (nitric oxide and nitrogen dioxide). They are produced from the reaction of nitrogen and oxygen gases in the air during combustion, especially at high temperatures.

NOx Sensor

Mounted in the exhaust system the NOx sensor monitors the amount of N0x in the exhaust stream. The information from this sensor is used to adjust the amount of DEF being injected, adjust fuel trim and monitor the efficiency of the SCR system.

Nucleus

The center of an atom. Protons and neutrons bond together to form the nucleus of the atom.

NVM

Non-Volatile Memory

NVRAM

Non-Volatile Random Access Memory

OASIS - Online Automotive Information System

A computer system that provides vehicle, warranty, recall,and ESP information about specific vehicles. OASIS is accessible by authorized Ford and Ford dealer employees using computer terminals at the dealership and at Ford Motor Company

OBD

On-Board Diagnostic

OC

Oxidation Catalytic Converter

OD

Overdirve

OEM

Original Equipment Manufacturer.

OHM

Measurement of electrical resistance. An Ohm is the amount of resistance to flow that will allow an Ampere of current to flow with 1 Volt of electrical pressure.

Ohmmeter

An instrument used for direct measurement of the electrical resistance of a material or electronic component, usually in ohms. Ohmmeters typically use an ammeter to measure current through the material after it has been given some set voltage by the ohmmeter; the direct-current resistance of the sample can then be directly determined through Ohm's law.

Ohm's law

A mathematical formula which shows the relationship between voltage, resistance, and current.

Oil Cooler

A heat exchanger that uses engine coolant to dissipate heat from the engine oil

OL

Open Loop

On-Board Diagnostics (OBD)

A system on board of the vehicle that monitors emission control components and alerts the driver (e.g., by a dashboard light) if malfunctions or emission deterioration occurs. The OBD system involves a number of sensors and a data processor, which is typically integrated with the vehicle's electronic management system

Open Circuit

An electrical circuit in which the path that the electrons follow cannot be completed because of an open gap that they cannot flow through.

Open Loop

An operating condition based on instructions not modified by PCM feedback

ORVR

On Board Refueling Vapor Recovery

OSC

Output State Control

OSHA

Occupational Safety and Health Administration - With the Occupational Safety and Health Act of 1970, Congress created the Occupational Safety and Health Administration (OSHA) to assure safe and healthful working conditions for working men and women by setting and enforcing standards and by providing training, outreach, education and assistance.

OSR

On Board System Readiness

OSS

Output Shaft Speed

Oxidation Catalytic converter - OC

A catalytic converter system that reduces the levels of HC and CO emissions

Oxidize

To combine with oxygen.

Oxygen Sensor - O2S

Provides information on rich or lean exhaust conditions to the PCM

Parallel Circuit

A circuit in which the current divides into two or more paths before recombining to complete the circuit.

Particulate Matter - PM

Particles formed by incomplete combustion of fuel. Compression ignition (diesel) engines generate significantly higher PM emissions than spark ignited engines. The particles are composed of elemental carbon, heavy hydrocarbons (SOF), and hydrated sulfuric acid (sulfate particulates)

Passive Regeneration

Occurs when exhaust temperatures are high enough during normal engine/vehicle operation to oxidize the soot in the DPF faster than it is collected.

PATS - Passive Anti-Theft System

A vehicle security system that prevents engine operation if a theft attempt is detected. It protects against theft by requiring a specially coded ignition key that transmits a unique code to the vehicles computers. The vehicle starts and operates only with the key that matches the key code programmed to the vehicle

PCM - Powertrain Control Module

The housing that contains the micro computer, VREF regulator, input conditioners and output drivers

PCV - Pressure Control Valve

A fuel control valve permanently attached to the high pressure fuel pump in a 6.4L PSD engine. The PCV governs the fuel pressure that is delivered to the fuel injectors and acts as a dampening device for the fluctuations in pressure that occur during fuel delivery through the pump and the injection process

Pd

Palladium

PDS - Portable Diagnostic Software

PID

Parameter Identification

Pinpoint Test

A diagnostic test found in the workshop manual that helps diagnose the cause of a DTC or vehicle concern

PIP

Profile Ignition Pickup

Piston

In an engine, its purpose is to transfer force from expanding gasses in the cylinder to the crankshaft via a connecting rod

Piston Cooling Jets

A devices that sprays oil onto the underside of the piston head. This oil helps to cool the piston and may also provide some lubrication for the piston pin.

Potentiometer

A type of variable resistor used to control voltage.

Positive Flow Deaeration

System using pressurized coolant flow to remove trapped air from the coolant.

Pour Point

A measure of the ability of a diesel fuel to operate under cold weather conditions. Defined as the temperature at which the amount of wax out of solution is sufficient to gel the fuel when tested under standard conditions (ASTM D97)

Power Stroke

The name used by a family of diesel engines for trucks produced by Ford Motor Company since 1994. Along with its use in the Ford F-Series (including the Ford Super Duty trucks), applications include the Ford E-Series, Ford Excursion, and Ford LCF commercial truck, Ford Transit and F-150; the name was also used for a diesel engine used in South American production of the Ford Ranger. From 1994, the Power Stroke engine family existed as a re-branding of engines produced by Navistar International, sharing engines with its medium-duty truck lines. Since the 2010 introduction of the 6.7L PowerStroke V8, Ford has designed and produced its own diesel engines.

PPM - Parts Per Million

A measure of concentration that is used where low levels of concentration are significant. The ppm value is equivalent to the absolute fractional amount multiplied by one million.

Pre combustion Chamber

A small, auxiliary combustion chamber connected by a narrow orifice with the main chamber. Fuel is injected into the pre chamber and ignites there, causing hot gases to expand into the main chamber (cylinder)

Protocol

The electronic language that network modules use to communicate

Proton

A basic particle of an atom. Protons have a positive charge or polarity. Protons and neutrons bond together to form the nucleus of the atom.

PSI

Pounds per Square Inch - a measurement of pressure.

PSP

Power Steering Pressure

Pt

Platinum

PTO - Power Take Off

A device mounted to the engine or transmission that provides power for accessories such as hydraulic pumps, compressors and generators.

PTS

Professional Technician Society Website

Pushrod

A metal rod that transmits reciprocating motion from a camshaft to the valves of an internal combustion engine having the camshaft in the crankcase

PWM - Pulse Width Modulation

A process of switching the power to a device on and off at a given frequency, with varying on and off times. These on and off times are referred to as "duty cycle".

PZEV

Partial Zero Emission Vehicle

QuickServe Online

The Cummins Corporation's online service information system.

RAM - Random Access Memory

Memory into which information can be written as well as read

Rectifier

An electronic device, such as a semiconductor diode or valve, in which current flows more readily in one direction than the other, for changing an alternating current into a direct current.

Reductant

Also known as diesel exhaust fluid is 32.5% urea and water

Relative Compression Test

A test that can be run with the Ford scan tool to measure compression of a cylinder relative to the other cylinders in the engine. This test is accomplished by comparing the rpm of the engine during each compression stroke

Regeneration

As related to diesel particulate filters, regeneration is the oxidation of soot trapped on the walls of a Diesel Particulate Filter. This process restores efficiency of the filter.

Relay

An electromechanical device in which connections in one circuit are opened or closed by changes in another circuit

Relative Compression Test

A diagnostic test performed with an electronic scan tool that measures variations in crankshaft speed between all of the cylinders by using data from the crankshaft and camshaft position sensors. A cylinder with lower compression will have less affect on engine speed than a cylinder with higher compression. When a cylinder with low compression is in the compression stroke, there will be a detectable variation in crankshaft speed. The term "relative" means just that: we are measuring the difference between the cylinders and not the actual compression. This test is useful in identifying cylinders with low compression quickly and it can pick up cylinder damage, worn or sticking valvetrain components and so on.

Resistance

The opposition to current flow.

Resistor

An electrical device designed to limit current flow due to the type of material from which they are constructed.

RFI

Radio Frequency Interference

Rh

Rhondium

Rheostat

A type of variable resistor so constructed that its resistance may be changed without opening the circuit in which it is connected, thereby controlling the current in the circuit.

Rocker Arm

A reciprocating lever that conveys radial movement from the cam lobe into linear movement at the poppet valve to open it. One end is raised and lowered by the rotating lobes of the camshaft (either directly or via a tappet (lifter) and pushrod) while the other end acts on the valve stem

Rocker Arm Carrier

A housing that the rocker arms and their fulcrums are mounted to

RPM

Revolutions Per Minute

ROM = Read-Only Memory

Computer memory that can be accessed and used, but not altered

RTD

Resistance Temperature Detector

RTV

Room Temperature Vulcanizing Compound - material used for form-in-place gaskets.

Runaway

Diesel engine which fails to respond to the usual controls and continues to accelerate after reaching its safe maximum speed, with consequent risk of major damage or disintegration. Even after the normal fuel supply is shut off the engine may continue to run, fuelled by lubricating oil vapor drawn past the piston rings from the crankcase, turbocharger or pooled oil in the intake system

RWD

Rear Wheel Drive

SAE

Society Of Automotive Engineers

SBDS - Service Bay Diagnostic System

A computer based diagnostic system that allows access to network that can perform self tests, monitor and record parameter data, program modules and can activate control module outputs. Tis service tool was retired in the early 1990's and replaced with the WDS diagnostic tool.

SCA - Supplemental Coolant Additive

Additive package used in diesel engine cooling systems to prevent scale, corrosion, and pitting of cooling system components.

SCB

Supercharger Bypass

SCCM

Steering Column Control Module

SCP - Standard Corporate Protocol

Schematic

A diagram that shows the functional relationship of components of a system.

SCR - Selective Catalytic Reduction

A means of converting nitrogen oxides, also referred to as NOx with the aid of a catalyst into diatomic nitrogen, N2, and water, H2O

SCR Catalyst

The Aftertreatment SCR Catalyst contains an element constructed of a cordierite monolith substrate that is used in the reduction of nitrogen oxides produced by the engine, the aftertreatment SCR catalyst element also works to reduce particulate emissions from the engine.

SEIC

Stationary Elevated Engine Idle Control is a powertrain control module (PCM) strategy that provides elevated engine speed to drive auxiliary commercial equipment such as hydraulic pumps, generators, air compressors or maintain vehicle battery charge.

Semi-conductor

Materials whose atoms are neither especially good or poor at giving up electrons. Semi-conductors are important in electronics because they are used to make transistors and integrated circuits. Silicon is an example.

Series circuit

A circuit in which the current flows in only one path from the source to the load and from the load back to the source to complete the circuit.

Series/parallel circuit

A circuit in which part of the circuit is connected in series and part of the circuit is connected in parallel with the source.

Serpentine Belt

Compound curve drive belt that uses both sides of the belt to drive engine accessory components.

SFI

Sequential Multiport Fuel Injection

Shield

A conducting sleeve that surrounds wires to be electronically isolated from electromagnetic interference (EMI)

Short Circuit

an abnormal, usually unintentional condition of relatively low resistance between two points of a circuit or between multiple circuits, usually resulting in a flow of excess current

SHRTFT

Short-Term Fuel Trim

SIG RTN - Signal Return

A dedicated sensor ground circuit that is common to 2 or more sensors

Solder Bloom

Corrosion of the soldered joints in a radiator or oil cooler caused by antifreeze with depleted corrosion inhibitors. Solder bloom can cause the tube-to-header joints to become weakened and corrosion can restrict coolant flow.

Soot

Impure carbon particles resulting from the incomplete combustion of hydrocarbons.

Split Shot Injector

Split Shot Injectors provide improved exhaust emissions and quiets engine operation by tailoring the injection of fuel, without a decrease in performance

SRS

Safety Restraint System - various system types may include driver and passenger airbags, side curtain airbags, safety belt retractors and steering wheel retractors

SSCC

"Symptom to System to Component to Cause" is a diagnostic strategy that allows a technician to diagnose vehicle concerns in a logical sequence

Stationary (Parked) Regeneration

Regeneration initiated by user interaction.

Stiction

A term based on the blending of "static friction" perhaps also influenced by the verb "stick." Two solid objects pressing against each other (but not sliding) will require some threshold of force parallel to the surface of contact in order to overcome static cohesion. Stiction is a threshold, not a continuous force. As applied to our profession, the spool valves in certain fuel injectors can stick due to the viscosity of the engine oil coating them. This can cause a spool valve to stick or operate in a delayed or slow motion causing drivability issues

Stub

The J1939 Datalink connection from service tools or other vehicle controllers that attaches to the J1939 backbone. The stubs are restricted to approximately 1 meter in length to minimize interference. The stub is constructed with shielding and twisted pair wires.

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

Stroke

The distance from the top of a piston's travel to the bottom or the distance a piston travels during one half turn of the crankshaft.

Sulfur

A pale-yellow, brittle nonmetallic element that occurs widely in nature, especially in volcanic deposits, minerals, natural gas, and petroleum. It is used to make gunpowder and fertilizer, to vulcanize rubber, and to produce sulfuric acid. Sulfur is a natural part of the crude oil from which diesel fuel is derived, is one of the key causes of particulates or soot in diesel.

Switch

A device that intentionally breaks the electrical path. A switches is used to open and a close circuit.

Symptom Chart

A chart found in the workshop manual that uses symptom descriptions to direct technicians to specific diagnostic tests or diagnostic routines

TAC

Throttle Actuator Control

TACM

Throttle Actuator Control Motor

Tappets

Camshaft followers or Lifters.

TC

Turbocharger

TCBP/CACT

Turbocharger Boost Pressure / Charge Air Cooler Temperature

TCBY

Turbocharger Bypass

TCCM

Transfer Case Control Module

TCIPT

Turbocharger Intake Pressure And Temperature

TCM

Transmission Control Module

TCS

Transmission Control Switch

TDC

Top Dead Center

Termination Resistor

One of the two 120 ohm resistors connected in parallel in the J1939 backbone circuit.

Thermistor

Sensor used to determine temperature. A thermistor changes it's resistance value in relation to temperature change. Increasing temperature results in decreasing resistance, decreasing temperature results in increasing resistance. The thermistor in conjunction with a current limiting resistor in the PCM forms a voltage divider that provides a voltage signal indicating temperature. Since the top half of the voltage divider is the current limiting resistor and is internal to the PCM, a thermistor sensor only has two connections, signal return and ground

Thermocouple

A device consisting of two different conductors (usually metal alloys) that produce a voltage, proportional to a temperature difference, between either ends of the two conductors widely used to measure temperature.

Thermostat

An automatic temperature sensing device used to control engine temperature by regulating the flow of coolant.

Thrust Bearing

A bearing that controls the amount of endplay of a shaft.

TIVCT

Twin Independent Variable Camshaft Timing

Tone Ring/Wheel

A notched ring, commonly installed on a crankshaft or camshaft. The notches or protrusions on the wheel disrupt the magnetic field of a closely positioned magnetic pickup sensor that creates a sine wave voltage.

Top-Dead-Center - TDC

The furthest point of a piston's travel, at which it changes from an upward to a downward stroke

Torque

A turning or twisting force that tends to cause rotation.

Torque-To-Yield

Also known as angle torque, torque to turn or torque plus angle. A tightening procedure that provides a more consistent clamping force than torque only. This is accomplished by torquing a fastener to a specification and then rotating an additional specified number of degrees or turns.

TP

Throttle Position

TPMS (Tire Pressure Monitoring System)

A tire pressure monitoring system (TPMS) is an electronic system to monitor the air pressure inside a pneumatic tire. They are sometimes referred to as remote tire pressure monitoring systems (RTPMS) or simply as run flat indicators. This system is required on all light motor vehicles under 10,000 lbs sold after September 1, 2007. For more information Google "TREAD Act."

TPPC

Throttle Plate Position Controller

TR

Transmission Range

TSB

Technical Service Bulletin

TSS

Turbine Shaft Speed Sensor

Turbine Wheel

The finned wheel on the exhaust side of a turbocharger that is propelled by the exhaust gasses leaving the engine

Turbocharging

A process of compressing the engine intake air charge in order to allow more air and fuel into the cylinder and, thus, to increase the engine power output. The compressor, called the turbo charger, is driven by an exhaust gas propelled turbine

Turbocharger Speed Sensor

This sensor measures the rotational speed of the turbocharger shaft and helps the ECM determine that the system is functioning and prevents overspeeding of the turbo.

Turbo Flutter

Is the rapid, cyclic air rushing noise heard from the air intake system on turbocharged engines. The noise is caused by air compressed by the turbocharger passing back through the it's compressor wheel after the airflow is abruptly decreased. This is also known as compressor surge. This condition is typically a combination of excessive boost pressure caused by a malfunctioning turbocharger and sudden engine deceleration.

Turbo Lag

The time delay between injecting fuel to accelerate and delivering air to the intake manifold by the turbocharger. This phenomenon may cause black smoke emissions in some turbocharged diesel engines during acceleration

TWC

Three-Way Catalytic Converter

ULSD - Ultra Low Sulfur Diesel

Ultra low sulfur diesel is diesel fuel that has been refined so that its sulfur content is 15 parts per million (ppm) or less.

UVCH - Under Valve Cover Harness

The injector wiring for the fuel injectors located under the valve covers of Power Stroke engines

Valve Seats

Create a seal between valves and the intake and exhaust ports in cylinder heads. Using specific angles, valve seats can either be machined directly into a cylinder head or inserts installed into the cylinder head.

Variable Capacitance Sensor

A sensor that is used to determine pressure. A variable capacitance sensor changes it capacitance value in relation to pressure change. Increasing pressure results in a lower capacitance, thus increasing return voltage. Decreasing pressure results in a higher capacitance and a lower voltage. Variable capacitance sensors are 3 wire sensors

Variable Resistor

A resistor with the ability to have its resistance value changed.

VCM - Vehicle Communication Module

A vehicle serial communications gateway that provides multiple vehicle serial communication interfaces that allow scan tools and computers to communicate with Ford Motor Company vehicles. The VCM is used with the Ford WDS, NGS, and IDS diagnostic scan tools

VCT

Variable Cam Timing

VCV - Volume Control Valve

A control valve permanently attached to the high pressure fuel pump in a 6.4L PSD engine. The VCV regulates the delivery of fuel from the internal transfer pump to the high pressure pumping elements and adjusts the low pressure side of the system to match the needs of the engine thus increasing efficiency

VECI

Vehicle Emission Control Information

Venturi

a short tube with a tapering constriction in the middle that causes an increase in the velocity of flow of a fluid or a gas and a corresponding decrease in pressure. Known as the "Venturi Effect" it is used especially in measuring fluid flow or for creating a suction.

VGT - Variable Geometry Turbocharger

A turbocharger that has a turbine housing that can change sizes through electronically controlled hydraulics

VGTCV - Variable Geometry Turbocharger Control Valve

Could also be called EVRTCV. Controls oil flow in and out of the VGT actuator in order to change the effective size of its turbine housing

VID

Vehicle Identification

VIN

Vehicle Identification Number

Viscosity

A fluid's resistance to flow.

Viscous Damper

A vibration damper used to reduce vibration and noise.

Visctronic Fan Clutch

A viscous cooling fan clutch that employs an electronically controlled clutch. The fan drive is controlled by the engine's control module for precise fan speed modulation.

Voltage

Electrical pressure.

Voltmeter

An instrument used for measuring the difference in voltage between two points in an electric circuit. Voltmeters typically make use of an ammeter that measures current flow across a known resistance inside the voltmeter; direct-current voltages can then be determined by Ohm's law. Digital voltmeters employ A/D converters to provide the numerical value of the voltage displayed.

VPWR

Battery voltage

VR Sensor

Variable reluctance sensors (also known as magnetic pickup style sensors)

VREF

5 volt reference voltage generated by the PCM

VMM - Vehicle Measurement Module

The hardware and cables that provide instrumentation to the IDS. It's functionality includes ignition system tests, fuel pressure tests, fuel leak-down tests, injector flow test, secondary ignition, current probe functionality, oscilloscope, digital multi-meter, pressure and vacuum gauge and variable geometry turbocharger functional tests

VSS - Vehicle Speed Sensor

Normally a magnetic pickup style sensor that is mounted on the tailshaft of the transmission to indicate ground speed

WABAC

The WABAC Machine (pronounced, and often synonymous with, Wayback) refers to a fictional machine from the cartoon segment Peabody's Improbable History, an ongoing feature of the 1960's cartoon series The Rocky and Bullwinkle Show. The WABAC Machine is a plot device used to transport the characters Mr. Peabody and Sherman back in time. The meaning of the acronym is unknown, but mid-century, big-science project names, such as ENIAC and JOHNNIAC, often ended in "AC".

Wastegate

A device used on turbochargers to regulate boost by allowing exhaust to bypass the turbocharger turbine.

Watt

The unit of measure for electrical power. A derived unit of power in the International System of Units (SI), named after the Scottish engineer James Watt (1736–1819). The unit, defined as one joule per second, measures the rate of energy conversion or transfer.

WDS - World Diagnostic System

A Ford computer based vehicle diagnostic tool capable of reading and erasing codes in various control modules, viewing control module parameters, reprogramming control modules and performing tests.

WIF - Water-in-Fuel Sensor

Sensor mounted in the bottom of the fuel filter/water separator that indicates if too much water is contained in the bottom of the filter.

Wiring Diagram

A schematic drawing of the wiring of an electrical system. Wiring diagrams typically include connector numbers, wire/circuit numbers and wire colors for identification.

Wiring harness

Made up of multiple individual wires it provides electrical paths for power and grounds and for electrical signals and communication networks.

WOT

Wide Open Throttle

There are no terms that start with this letter.

There are no terms that start with this letter.

There are no terms that start with this letter.

2V

Two valves per engine cylinder

3V

Three valves per engine cylinder

4V

Four valves per engine cylinder

4WD

Four Wheel Drive