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The term used describe a two-wheel drive vehicle. The "4"
indicates thenumber of wheels of the vehicle and the "2"
indicates the number ofwheels that are driven by engine
Four by two
4x2."4"
,"2"().
The term used describe a four-wheel drive vehicle. The first
"4"indicates the number of wheels of the vehicle and the second"4"indicates the number of wheels that are driven by engine.
Most 4x4 drivetrains have a transfer case that allows thedriver
to select either two(4x2)- or four-wheel drive (4x4) depending
ondriving conditions. In trucks, youll often find locking hubs
on thefront wheels that can be locked in the "on" or free-
wheeling position asneeded. Some performance cars have full-
time variable four-wheel driveand use a computer-controlled
transfer case to route power between thewheels
Four by four
4x4
."4""4"
The 1991-92 systems are unique in that they used 4 wheelspeed sensors(one located at each wheel) while the other
systems use the VehicleSpeed Sensor (VSS) signal for rear
wheel speed.
4Wheel Anti Lock brake
4WAL
4()
4WD is a system in which the engine's power is (or can be)transmitted to all four wheels through a two-speed transfer case
anddrive axles. The transfer case's main function is to provide a
gear-reduction feature and the ability to shift the vehicle into
four-wheel "Low" range, which is designed for severe conditions
such aspulling through heavy snow or mud, or slowly climbingup (or inchingdown) a backwoods hunting trail.
A method of driving a vehicle by applying engine torque toall
four wheels. Various schemes are used for 4WD including part-
time,full-time and variable four-wheel drive. The primaryadvantage offour-wheel drive is increased tractionwhich is
especially useful foroff-road excursions or severe weather
driving, but is of littlepractical value for normal driving.
Because of the added friction in thedrivetrain, a four-wheel
drive vehicle typically gets significantlylower fuel mileage than
a front- or rear-wheel drive vehicle.
Four-wheel drive
4WD
,transfer cas.
(/,
)..,.
Unit of measuring the electric currentAmpereA
A system that cools and dehumidifies air entering thepassengercompartment. The system uses a refrigerant to cool
the air and carryheat away from the passenger compartment.
Major system componentsinclude a compressor, condenser,
Air ConditionerA/C
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evaporator, accumulator orreceiver/dryer, and orifice tube or
expansion valve. Do not intermixdifferent types of refrigerants
in an A/C system. Use the type specifiedby the vehicle
manufacturer (R12 for most 1994 and older vehicles, orR134a
for most 1995 and newer vehicles). See also Retrofit.
AAA (the American Automobile Association, Inc.) is not-for-
profitorganization. AAA provides certain standard services to its
own members,It is providing emergency roadside assistance toits members, also AAAoperates travel agencies and publishes
maps and travel guides, and otherservices as well.
American AutomobileAssociation
AAA
().,,
,,
Active Body ControlABC
An anti-lock braking system (ABS) (translated from German,
Antiblockiersystem) is a system on motor vehicles whichprevents thewheels from locking while braking. The purpose of
this is to allow thedriver to maintain steering control under
heavy braking and, in somesituations, to shorten braking
distances (by allowing the driver to hitthe brake fully without
the fear of skidding or loss of control)Since it came intowidespread use in production cars (with "version 2"in 1978),
ABS has made considerable progress. Recent versions not onlyhandle the ABS function itself (i.e. preventing wheel locking)
but alsotraction control, brake assist, and electronic stability
control,amongst others. Not only that, but its version 8.0 systemnow weighsless than 1.5 kilograms, compared with 6.3 kg of
version 2.0 in 1978.
Antilock braking systemABS
Electric current that reverses direction periodically, usually
manytimes per second. One complete period, with current flow
first in onedirection and then in the other, is called a cycle, and
60 cycles persecond (60 hertz) is the customary frequency of
alternation in theUnited States and in all of North America. In
Europe and in many otherparts of the world, 50 Hz is the
standard frequency. On aircraft ahigher frequency, often 400
Hz, is used to make possible lighterelectrical machines
Alternating Current
AC
,.,.60(60
).(50).
400,autonomous or adaptative cruise control (ACC) systems. The
system alsogoes under the names of active cruise control (ACC)
, adaptive cruisecontrol (ACC) or intelligent cruise control
(ICC). A radar sensor islinked to the ECU which slows the
vehicle and brakes if necessary.
Adaptive Cruise Control
ACC
ACC,ICC,
,
()
()
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Advanced Driver Assistance
SystemsADAS
AFS varies the steering transmission ratio electronically in
directrelation to the style and speed of driving and road
conditions
Active front steeringAFS
Alternative fuel vehicleAFV
The automated guided vehicle or automatic guided vehicle
(AGV) is amobile robot that follows markers or wires in the
floor, or uses visionor lasers. They are most often used in
industrial applications to movematerials around a manufacturing
facility or a warehouse. Application ofthe automatic guided
vehicle has broadened during the late 20th centuryand they are
no longer restricted to industrial environments.
Automated guided vehicle
AGV
,,,
.
A unit of electrical capacity. Tells you how much power the
battery will store. Current multiplied by time in hours equals
ampere-hours. A current of one amp for one hour would be one
amp-hour; acurrent of 3 amps for 5 hours would be 15 AH
CRLF.Ampere-Hour rating: is the amount of steady current thatafully charged battery can supply for 20 hours at 26.7oC
without the cellvoltage falling below 1.75 volts or 10.5 volts at
terminals.
Ampere-Hour
AH
...11-
.3515-.-:20
26.71.7510.5.
-
AHC systems exist under many trade names, including
Electronic Height Control (EHC), Variable Ride-Height
Suspension(VRHS), and pneumatic suspension systems.Active Height Control
AHC
Air injection into the exhaust port allows the unburnt andpartially burnt fuel to be completely combusted in the exhaust
system.This system sometimes called an after-burner and itoperates when theengine is slow-running or cruising.
Air injection
AI
.
,.
Automated Manual
TransmissionAMT
Active noise control
ANC
American Petroleum
InstituteAPI
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Automatic Stability ControlASC
ASE is a nonprofit, nonaffiliated organization formed tohelp
assure the highest standards in automotive service. It directs an
organized program of self-improvement.
Automotive Service
ExcellenceASE
Also called Traction Control System (TCS.)Acceleration slip regulation
Automatic slip regulationASR (TCS)
Some vehicles can be classified as AT-PZEV, standing for
Advanced Technology PZEV. This type of vehicle is just as
clean as aPZEV vehicle, but gets much better fuel efficiency
due to the use ofhybrid electric vehicle systems. This
technology can also be used in aSport Utility Vehicle to
improve their traditionally lower fuel economy;however theymay still lag behind the efficiency of smaller vehicle
Advanced Technology-
Partial Zero Emission
VehicleAT-PZEV
-
Automatic Tire Inflation
SystemATIS
A special kind of oil for use in automatic transmissions.There
are several types: Dexron II, Dexron III, Type F, Mercon,
MerconV, Chrysler 7176 and several varieties of Chrysler ATF-
Plus. All are"friction-modified" lubricants except Type F.Dexron II and Mercon havesimilar additive packages as do
Dexron III and Mercon V. Even so, useonly the type of ATF
specified by the vehicle manufacturer. Using thewrong type of
ATF can cause transmission problems. If you do not knowwhat
type of fluid the transmission takes, READ THE OWNERS
MANUAL! Somedipsticks are also marked as to the type of
ATF required. "Universal"ATF fluids are available thatsupposedly meet the OEM requirements formany friction-
modified applications, but make sure the label says itmeets the
specific vehicle requirements before using. The newer ATFs
such as Dexron III and Mercon V are longer lived than earlier
ATFs, butcan still oxidize if the transmission runs too hot.
Trailer towing isespecially hard on ATF unless the transmission
is equipped with anauxiliary oil cooler. Recommended changeinterval for older vehicles isevery 24,000 to 30,000 miles. For
newer vehicles, see the owners manual.
Automatic transmission fluidATF
All-terrain vehicle
ATV
A vehicle (usually a car) where all four wheels are driven.Most are fulltime systems for year-round driving, and use a
viscousfluid coupling center differential instead of a transfer
case to routedrive torque to all four wheels. This allows the
front and rear wheelsto turn at slightly different speeds when
turning on dry pavement.
All wheel driveAWD
or (BAS, Brake Assist System), which automatically applies
full brakingpower when a panic stop is sensed via rapid pedalBrake AssistBA
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movement, such aswhen the driver stabs the brakes
.
()
or(BA, Brake Assist)Brake Assist SystemBAS
(
Bottom dead centerBDC
Brake horse powerBHP
Ball joint inclinationBJI
A term relating to the pressure in the cylinder calculated form
the horsepower reading on a dynamometer.Brake mean effective
pressureBMEP(bmep)
.
Brake pressure modulator valve, it is part of the anti-lock
brakes andtraction control system.Also called the Electro-Hydraulic Control Unit (EHCU). During theAntilock mode, the
BPMV can maintain or reduce brake fluid pressureindependent
of the pressure generated in the master cylinder. The BPMVdoes not provide more pressure than is applied by the master
cylinderduring braking
Brake pressure modulator
valve
BPMV
,..
,.
.
automatic transmissions are equipped with "brake transmission
systeminterlocks" to prevent children from moving the shift
mechanisms out ofpark.
Brake Transmission Shift
Interlocks
BTSI
The amount of heat required to raise 1 pound of water 1 F at
sea levelBritish thermal unit
BTU
11The crank angle sensor (CAS) is a device used in the
automobile to tell the Engine Control Unit (ECU) when to fire
the sparkplugs. The CAS detects where the piston is located in
the engine andwhen it is in the right spot it tells the ECU to fire
the spark plug inthat cylinder.The sensor is typically located on
the flywheel or on aseparate cog. One of the teeth of theflywheel is missing, the oneexactly at Top Dead Center of
cylinder #1 (the closest to the flywheel.)The sensor registers achange and responding to this, sendsout a pulse to the ECU. The
ECU is then able to calculate the injectionand ignition timing.
There are two commonly applied versions of thissensor, based
on the principle of induction and on the Hall effect. Thissensor
is the most important sensor in modern day engines. When it is
failing, the engine will not run at all
Crank Angle SensorCAS
is an automotive safety system developed by BMW. It is a
furtherdevelopment and expansion of the anti-lock braking
system, designed todistribute braking force during emergency
braking whilst cornering. CBCinteracts with ABS to counteract
oversteer and guarantees optimumdistribution of brake power in
Cornering Brake ControlCBC
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corners, keeping the vehicle heading inthe intended direction
even if the brakes are applied suddenly
Cold Cranking Amps is a rating used in the battery industry to
define abattery's ability to start an engine in cold temperatures.
The ratingis the number of amps a new, fully charged battery
can deliver at 0Farenheit for 30 seconds, while maintaining a
voltage of at least 7.2volts, for a 12 volt battery. The higher the
CCA rating, the greater thestarting power of the battery.
Cold Cranking AmpsCCA
Capacitor-discharge ignition
CDI
A family of manmade chemicals containing chlorine that
include R12automotive air conditioning refrigerant. CFCs have
been blamed for adeterioration of the Earths protective ozone
layer. CFCs have beenphased out of production by international
agreement.CFCs have beenblamed for a deterioration of the
Earths protective ozone layer.
ChlorofluorocarbonsCFCs
Center of gravity(also called Center of mass). The point in a
systemof bodies or an extended body at which the mass of the
system may beconsidered to be concentrated and at which
external forces may beconsidered to be applied.
Center of gravity
CG
().
Compression ignitionCI1
Coil ignition
CI2
Compressed natural gasCNG
A deadly gas that results from the incomplete burning of
gasolineinside the engine, carbon monoxide is considered to be
a serious airpollutant. You cant see it or smell it, but it can kill
in very smallconcentrations. Because of this you should never
run an engine inside aclosed garage. Various means are used to
reduce the amount of COproduced by an engine, and primary
among these is the catalyticconverter. The converter "reburns"
CO in the exhaust and converts itinto harmless carbon dioxide.
Carbon MonoxideCO
The amount of friction between two surfaces is expressed as a
coefficient of friction (COF). The coefficient of friction is
determinedby dividing the force required to pull an object
across a surface bythe normal force between between the two
objects.
Coefficient of frictionCOF
A type of distributorless ignition system where individual
ignitioncoils are mounted directly over each spark plug. No
spark plug wires areused.Coil-On-Plug ignition
COP
,,().
The camshaft position sensor monitors engine speed and
piston position. These input signals to the ECM are used to
control fuelinjection, ignition timing and other functions. The
Camshaft (or Crankshaft)
Position SensorCPS
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camshaft positionsensor has a rotor plate and a wave-forming
circuit. The rotor plate has360slits for a 1(POS) signal and 6
slits for a 120(REF) signal.The wave-forming circuit consistsof Light Emitting Diodes(LED) and photo diodes. The rotor
plate is positioned between the LEDand the photo diode. The
LED transmits light to the photo diode. As therotor plate turns,
the slits cut the light to generate rough-shapedpulses. These
pulses are converted into on-off signals by thewave-forming
circuit and sent to the ECM.The engine coolant temperature sensor is used to detect the
enginecoolant temperature. The sensor modifies a voltage signal
from the ECM.The modified signal returns to the ECM as theengine coolant temperatureinput. The sensor uses a thermistor
that is sensitive to the change intemperature. The electrical
resistance of the thermistor decreases astemperature increases.
Coolant temperature sensorCTS
A crossover SUV (also called CUV for Crossover Utility
Vehicle) or XUVis an automobile with a sport utility vehicle
appearance but is builtupon a more economical and fuel-efficient car-based platform.
Crossover Utility Vehicle
CUV
,.
A Constant Velocity Joint is one that provides consistent
driveshaftspeeds regardless of the operating angle of the joint.
CV joints(U-joints (Universal joints)are used primarily in onthe driveshaftsof front-wheel drive vehicles, and they come in
two basic varieties: theRzeppa ball type joints (which youll
find on the outer end of thedriveshaft) and tripod joints (which
are used on the inner end.)
Constant velocity joint
CV joint(1)
,.
,,()(
.
()
Commercial vehiclesCV(2)
()
Continuously variable transmissions (CVTs) are another
transmissiontechnology that's available in some cars. Instead of
having fixed gearratios like a conventional manual or automatic,
CVTs constantly adjustto the current driving conditions. Sincethere are no gear "steps" toshift between, CVTs often operate
more smoothly than other technologies.
Continuously variable
transmissionCVT
It is an automotive technology that allows the intake and/or
exhaustvalve timing to be infinitely varied during engine
operation.
Continuous Variable Valve
TimingCVVT
Direct currentDC
Direct Drive (transmission)DD
()Direct Fuel Injection
DFI
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Direct Ignition SystemDIS
do-it-yourself job
DIY job
An ignition system that does not use a distributor to route high
voltage to the spark plugs. The high voltage plug wire runs
directlyfrom the ignition coil to the spark plug. Some DIS
systems have one coilfor every two spark plugs (a sharedsystem), while others have aseparate coil for each spark plug
(See Coil-On-Plug Ignition.)Eliminating the distributor makesthe system more reliable andeliminates maintenance.
Distributorless Ignition
systemDLI
Also, called digital volt/ohmmeter (DVOM.)Digital multi meter
DMM
Department of Motor
VehiclesDMV
()
Cylinder Deactivation, Multiple Displacement System (MDS),
or Variable Cylinder Management.Displacement on demandDOD
The U.S. Department of EnergyDepartment of Energy
DOE
DOHC dual overhead cam engine has two camshafts in
cylinder head. Camsact directly on valves without rocker arms.
One cam operate the intakevalves the other operate the exhaust
valves.
Dual over head camDOHC
The U.S. Department of TransportationDepartment of
TransportationDOT
DOT 3 BRAKE FLUID; Brake fluid that meets the
Department ofTransportation specifications for glycol based
fluids with a wet boilingpoint (lowest allowable after its been
in use) of 284 degrees F. and adry boiling point of 401 degrees
F. DOT 3 fluid is the type commonlyspecified by most vehicle
manufacturers. Because it is glycol based, itabsorbs moisture
over time (hygroscopic). This lowers its effectiveboiling point
and promotes internal corrosion in the brake system. Forthis
reason, the brake fluid should be replaced periodically (every
twoyears is recommended by many experts) and every time thebrakes arerelined or serviced.DOT 4 BRAKE FLUID; A
"heavy-duty" glycol based brake fluidwith a slightly higher wet
boiling point of 311 degrees F. and a dryboiling point of 446
degrees. This type of fluid is sometimes specifiedfor
performance vehicles or those subject to high brake
temperatures.DOT 5 BRAKE FLUID; A silicone based fluidthat does not absorb moistureand has a boiling point of at least
500 degrees F. DOT 5 fluid does nothave to be changed
periodically and can minimize brake system corrosion,but isvery expensive compared to DOT 3 or DOT 4 fluid (it costs
threeto five times as much). It will not mix with DOT 3 or DOT4 brake fluid.DOT 5 is NOT recommended for any vehicle with
ABS brakes because ittends to aerate when cycled rapidly
through small orifices.
DOT 3, DOT
4, DOT 5
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Dynamic Stability ControlDSC
The DSG removes the clutch pedal and associated operation,
and placesit under the control of computer chips and hydraulic
servos. When leftin full auto mode, it's as smooth as or
smoother than any conventionalautomatic.
Direct Shift GearboxDSG
Computerized engine control systems have a certain amount ofbuilt-inself-diagnostic capability to detect problems that affect
engineperformance and emissions. The same is true for the
antilock brakesystem and other onboard systems that are
computer controlled. When afault is detected, the computer will
store a diagnostic trouble code inits memory and illuminate the
"Check Engine" light. On some vehicles,the computer can beput into a special diagnostic mode by groundingcertain
terminals on a diagnostic connector. This will cause the Check
Engine or other lights to flash out the fault code. On many
vehicles,though, a scan tool must be plugged into the computer
system to accessand read the codes.
Diagnostic trouble codsDTCs
()
Driving under the influenceDUI
Emergency Brake Assist (EBA) is a safety system in vehicles
designed toensure maximum braking power is used in an
Emergency stop situation. Byinterpreting the speed and pressure
at which the brake pedal is pushed,the system detects if thedriver is trying to execute an emergencystop, and if the brake
pedal is not fully applied, the system overridesand fully applies
the brakes until the Anti-lock braking system (ABS)takes overto stop the wheels locking up
Modulus of elasticityE
which automatically applies more braking power to the wheels
with thebest grip. Also called (EBFD). Often coupled with anti-
lock brakingsystems, EBD can apply more or less braking
pressure to each wheel inorder to maximize stopping power
whilst maintaining steering control.
Electronic brake-force
distributionEBD
Electronically controlled
brakesECB
or ECU electronic control unit is an embedded system that
controls one or more of the electrical subsystems in a vehicle.Electronic control module
ECM
Also called coolant temperature sensor (CTS.)Engine coolant temperature
sensorECT
or ECM electronic control module is an embedded system that
controls one or more of the electrical subsystems in a vehicle.Electronic control unit
ECU
The eCVT in the hybrid car is integral with the generator
motor. Itharnesses internal combustion and electric power
sources to drive thewheels.
Electronically controlled,
continuously variable
transmissioneCVT
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Electronic diesel control unitEDCU
EDTC prevents excessive slip of the driven wheels due to
engine dragtorque (engine brake). This may occur when driving
on slippery roadsurface if the driver change to lower gear or
suddenly lifts his footoff the throttle.
Engine drag traction controlEDTC
............. Abbreviation for Electronic Fuel Injection. This type of systemusescomputer-controlled fuel injectors to spray fuel into the
engine ratherthan mechanically controlled injectors or a
carburetor. EFI comes inseveral varieties: "throttle body
injection" (See TBI), "multi-portinjection" (See MFI or PFI) or
Sequential Fuel Injection (SFI.)Electronic fuel injection isconsidered to be superior to carburetionbecause it allows more
precise fuel metering for easier starting, loweremissions, better
fuel economy and performance.
Electronic fuel injectionEFI
The EGO sensor is mounted in the exhaust system upstream of
thecatalyst. It detects excess oxygen in the exhaust stream.
Oxygen, or thelack of it, indicates whether the air/fuel is lean or
rich of thestoichiometric ratio. The EGO sensor is also known
as a Lambda-Sondsensor or O2 sensor.
Exhaust Gas Oxygen SensorEGO
This is an emissions control technique for reducing oxides of
nitrogenemissions in the tailpipe. A small amount of exhaust gas
is recirculatedback into the intake manifold to dilute the
incoming air/fuel mixture.Contrary to what youd think, it has acooling effect on combustiontemperatures which helps reduce
the formation of oxides of nitrogen (SeeNOX). The EGR valve
is the main control device in this system.
Exhaust-gas recirculationEGR
()
EHC systems exist under many trade names, including
VariableRide-Height Suspension (VRHS), Active Height
Control (AHC), andpneumatic suspension systems.Electronic Height Control
EHC
Electro-hydraulic power
steeringEHPS
Electronic IgnitionEI
Pure brake by wire, no brake fluid, no brake lines, electric
motorgenerates braking force, and wheel brake ECU actuated
from electronicbrake pedal
Electro Mechanical BrakeEMB
In an Engine Management System (EMS), electronics control
fueldelivery, ignition timing and firing order. Primary sensors
on thesystem are engine angle (crank or Top Dead Center
(TDC) position,)airflow into the engine and throttle demandposition. The circuitrydetermines which cylinder needs fuel and
how much, opens the requisiteinjector to deliver it, then causes a
spark at the right moment to burnit. Early EMS systems usedanalogue computer circuit designs toaccomplish this, but as
embedded systems became fast enough to keep upwith the
Engine Management SystemEMS
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changing inputs at high revolutions, digital systems started to
appear.
Abbreviation for the Environmental Protection Agency, the
governmentagency responsible for enforcing anti-pollution
rules. The EPA requiresall vehicle manufacturers to certify their
new car as being incompliance with the applicable clean air
standards for the year ofmanufacture. The manufacturer, in turn,
must provide an "emissions"warranty on every vehicle they sellthat guarantees free replacement ofany emissions control device
that might fail during that time. Thiscoverage usually extends to
such items as the computer control system,catalytic converter,fuel and ignition system (except the spark plugsand normal wear
items.)
Environmental ProtectionAgencyEPA
Evaporator pressure
regulatorEPR
Electronic power steeringEPS
ESC systems exist under many trade names, including Vehicle
StabilityControl (VSC), Electronic Stability Program (ESP), and
Vehicle StabilityEnhancement (VSE.)Electronic Stability Control
ESC
ESP systems exist under many trade names, including Vehicle
StabilityControl (VSC), Electronic Stability Control (ESC), and
Vehicle StabilityEnhancement (VSE.)Electronic stability program
ESP
Electronic throttle control
ETC(1)
The Electronic Transmission is an automatic transmission
which uses modern electronic control technologies to control the
transmission. The transmission itself, except for the valve body
andspeed sensor, is virtually the same as a full hydraulically
controlledtransmission, but it also consists of electronic control
unit andactuators.The electronic sensors monitor the speed ofthe vehicle,gear position and throttle opening, sending this
information to the ECU.The ECU then controls the operation ofthe clutches and brakes based onthis data and controls the
timing of shift points and torque convertertock-up.
Electronic Traction ControlETC(2)
Electronic transmission
control unitETCU
Emergency tensioning
deviceETD
Electric vehicle
EV
Electronic Wedge Brake
EWB
Free body diagramFBD
Fuel cell vehicle
FCV
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Forward Collision WarningFCW
Flexible fuel vehicles (FFVs) are designed to run on gasoline
or ablend of up to 85% ethanol (E85). Except for a few engine
and fuelsystem modifications, they are identical to gasoline-only
models.
Flexible-fuel vehicleFFV
fixed geometry intake manifold.fixed geometry intakemanifold.FGI
Federal Motor Vehicle
Safety StandardsFMVSS
A means of driving a vehicle by applying engine power to the
frontwheels instead of the rear wheels. There are advantages and
disadvantages to front-wheel drive. On the plus side, the
advantages gomostly to the vehicle manufacturers because it
makes it easier for themto package a vehicle
engine/drivetrain/body combination moreefficiently. In other
words, the same basic engine/drivetrain packagecan be installedunder a variety of "different" model cars. The samebasic
engine/transaxle package Chrysler developed for their Omni and
Horizon (which they basically copied from Volkswagen) can be
found underall their current front-wheel drives ranging from the
mini-vans to thesports sedans. Thus a manufacturer can save a
bundle in tooling anddevelopment when he wants to bring a new
front-wheel drive model to theshowroom floor. As far as FWD
being superior to RWD, its mostly hype.Some people willargue that front-wheel drive handles better thanrear-wheel drive
while others will argue exactly the opposite. Porscheand
Mercedes seem to be unimpressed by FWD, and most race carsarerear-wheel drive. On the negative side, some front-wheel
drive cars havea tendency to "torque steer" (See Torque Steer),
and transaxle problemscan be very costly to repair because it
often involves pulling theengine.
Front wheel driveFWD
The shear modulus or modulus of rigidity (G or ) describes an
object'stendency to shear (the deformation of shape at constant
volume) whenacted upon by opposing forces; it is defined as
shear stress over shearstrain. The shear modulus is partof the
derivation of viscosity.
Modulus of rigidityG
gram per milegpm
The Global Positioning System (GPS) is a global navigation
satellitesystem (GNSS) developed by the United States
Department of Defense andmanaged by the United States Air
Force 50th Space Wing. It is the onlyfully functional GNSS in
the world, can be used freely, and is oftenused by civilians for
navigation purposes. It uses a constellation ofbetween 24 and 32
medium Earth orbit satellites that transmit preciseradiowave
signals, which allow GPS receivers to determine their current
location, the time, and their velocity. Its official name isNAVSTARGPS. Although NAVSTAR is not an acronym, a few
backronyms have beencreated for it.Since it became fullyoperational in 1993, GPS has become a widely usedaid to
Global positioning systemGPS
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navigation worldwide, and a useful tool for map-making, land
surveying, commerce, scientific uses.
Abbreviation for gross vehicle weight. GVW is the weight of
the vehicleplus the weight of all passengers and cargo up to the
limit specifiedby the manufacturer
Gross vehicle weightGVW
is the maximum allowable total weight of a road vehicle ortrailer thatis loaded, including the weight of the vehicle itself
plus fuel,passengers, cargo, and trailer tongue weight.Gross vehicle weight rating
GVWR
Acronym for "Heating, Ventilation and Air ConditioningHeating, Ventilation and Air
ConditioningHVAC
,,
A hydrocarbon (HC) is any kind of substance that contains
hydrogen andcarbon. Gasoline is a hydrocarbon. So is oil. When
gasoline burns insidean engine, there is always a tiny amountthats left over. If an engineis misfiring because of a fouled
spark plug or a leaky valve, or if ithas worn rings or valveguides and uses oil, quite a bit of unburned HCcan pass through
into the exhaust. Unburned HC is a major source of airpollution
and is the primary source of smog in most urban areas. Various
means are used to reduce the amount of HC an engine produces,
theprimary one of which is the catalytic converter. The
converter reducesHC emissions by "reburning" and converting
it into harmless water vapor
Hydro carbonHC
is a form of internal combustion in which well-mixed fuel and
oxidizer(typically air) are compressed to the point of auto-ignition.
Homogeneous charge
compression ignitionHCCI
Hybrid electric vehicle
HEV
The HO2S is placed into the exhaust manifold. It detects the
amount ofoxygen in the exhaust gas compared to the outside air.
The sensor has aclosed-end tube made of ceramic zirconia. The
zirconia generates voltagefrom approximately 1V in richer
conditions to 0V in leaner conditions.The sensor signal is sent tothe ECM. The ECM adjusts the injectionpulse duration to
achieve the ideal air-fuel ratio. The ideal air-fuelratio occursnear the radical change from 1V to 0V.
Heated Oxygen SensorHO2S
Hydraulic Power Steering
HPS
Headway Monitoring
HWM
Highway
hwy
Symbol of electric currentElectric current
I
Intake air temperature sensor. Also has a verity if names inthepast (ACT, VAT, MCT, MAT and ATS) under OBD II
guidelines, theseparts are now called IATs.The intake airtemperature sensor is mounted to the air ducthousing. The
Intake air temperatureIAT
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sensor detects intake air temperature and transmits asignal to the
ECM. The temperature-sensing unit uses a thermistor thatis
sensitive to the change in temperature. Electrical resistance of
thethermistor decreases in response to the temperature rise
Integrated circuit
IC
Also named Adaptive Cruise Control(ACC)Intelligent Cruise ControlICC
()
Internal combustion engineICE
Independent Front
SuspensionIFS
Insurance Institute for
Highway SafetyIIHS
Independent RearSuspensionIRS
Idle Speed Control system
ISC
Integrated Starter/Generator
ISG
/
Idle Speed Control ValveISCV
Energy unit (1Joule = 1 Newton meter)Joule
J
(1=1)
kilo = 1000KiloK
1=1000The bulk modulus (K) describes volumetric elasticity, or the
tendencyof an object's volume to deform when under pressure;
it is defined asvolumetric stress over volumetric strain, and is
the inverse ofcompressibility. The bulk modulus is an extension
of Young's modulus tothree dimensions
Bulk modulusK
Toyota also demonstrated its Kinetic Dynamic Suspension
System (KDSS). By allowing the decoupling of thefront and
rearstabilizer bars, KDSS allows greater suspension articulation
(movement,that is) off-road.The KDSS-assisted truck was ableto keep all its tires incontact with the ground due to the greater
suspension travel afforded bythe system, while the one with
KDSS switched off has a rear tireclawing at thin air.Anotherbenefit of KDSS is that it allows larger stabilizerbars for
improved on-road handling via decreased body roll.
Kinetic Dynamic Suspension
SystemKDSS
The angle formed by a line that runs through the king pin in
the steering knuckle on a truck with an I-Beam axle. Its the
same asthe steering axis inclination (SAI.)
King pin inclinationKPI
The knock sensor is mounted on the engine block. It detects
the vibration caused by detonation.Knock sensor
KS
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A liter is a metric unit of measure for volume. One liter is
equal to one thousand milliliters cube.Liter
l.1000
.Left
L
A "Liquid Crystal Display" is a type of electronic display that
formsopaque or dull-colored letters or numbers on variousbackgrounds. LCDdisplays are popular for digital dashboards,
but they are not asreadable in direct sunlight as LED displays
Liquid crystal displayLCD
Lain Departure Warning
LDW
()
A light emitting diode emits light when current is passed
through it in the forward direction.A "Light Emitting Diode" isan electronic light bulb ofsorts that produces colored light.
Youll find LEDs used in the centerhigh mounted stop light on
many vehicles, and used as indicator lightsin some
instrumentation. LEDs are also used in some vehicle speedsensors and in some electronic ignitions.
Light emitting diode
LED
Low emission vehicleLEV
Liquefied natural gas
LNG
Liquefied petroleum gas
LPG
Limited-slip differentialLSD
Length unitmeterm
Tire rating for mud and snowM+S, MS, M/S or M and SMud and snow
M+S
The mass airflow sensor is placed in the stream of intake air. It
measures the intake flow rate by measuring a part of the entire
intakeflow. It consists of a hot wire that is supplied with electric
currentfrom the ECM. The temperature of the hot wire is
controlled by the ECM acertain amount. The heat generated by
the hot wire is reduced as theintake air flows around it. Themore air, the greater the heat loss.Therefore, the ECM must
supply more electric current to maintain thetemperature of the
hot wire as airflow increases. The ECM detects theairflow by
means of this current change.
MassAir flow sensorMAF
A fuel injection system that opens its injectors in pairs or
groups a sufficient amount of time prior to intake valve opening
so theintake port is filled with fuel before the valve opens.TheManifold Absolute Pressure sensor measures changes inthe
intake manifold pressure resulting from engine load and speedchanges. The computer sends a 5-volt reference signal to the
MAP sensor.As pressure changes in the intake manifold occur,the electricalresistance of the MAP sensor also changes. By
monitoring the sensoroutput voltage, the computer can
Manifold absolute pressure
(sensor)MAP
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determine the manifold absolutepressure. The higher the MAP
voltage output the lower the engine vacuum,which requiresmore fuel. The lower the MAP voltage output the higherthe
engine vacuum, which requires less fuel. Under certain
conditions,the MAP sensor is also used to measure barometricpressure. This allowsthe computer to automatically adjust for
different altitudes. Thecomputer uses the MAP sensor to control
fuel delivery and ignitiontiming.
Cylinder Deactivation, DisplacementOn Demand (DOD), or
Variable Cylinder Management.Multiple Displacement
SystemMDS
Mechanical Efficiency
ME
Abbreviation for Multi-port Fuel Injection, a type of fuel
injectionsystem that has one injector for each engine cylinder.
Each injectorsprays its fuel directly into the intake port in the
cylinder head.Multi-port fuel injection is considered to be the
"hot" setup because itprovides better cylinder-to-cylinder fueldistribution for more power.
Multi-port Fuel InjectionMFI (MPI)
Abbreviation for Miles Per Gallon. A vehicles fuel economy
isdetermined by a number of factors including the size of the
engine, thetype of carburetion used, the weight of the vehicle,
the type oftransmission used (manual or automatic), the final
drive ratio, the sizeand type of tires used, tire inflation
pressures, aerodynamicstreamlining of the body, the driving
habits of the driver, the kind ofroad surface and terrain upon
which the vehicle is driven, the speed atwhich its driven, and
environmental factors such as temperature, windand humidity.Taking all these into consideration, its no wonder theEPA says
"the mileage you get may vary from the official EPA estimates".
Mile per gallonMPG (mpg)
Multiport fuel injection
MPI (MFI)
Multi-purpose vehicleMPV
Unit of measuring force (1 Newton = 1 kg m/s.s)Newton
N(1=1/.)
NeutralN
The North American Automobile Trade Association (NAATA)
is anot-for-profit association of vehicle dealers that buy and sell
vehiclesacross international borders.
The North American
Automobile Trade
AssociationNAATA
.
No cause for removalNCFR
Abbreviation for the National Highway Traffic and Safety
Administration. This is the government agency that is
responsible formaking and policing safety rules for all vehicles.
NHTSA is the agencythat can order a vehicle manufacturer to
issue a safety recall.
National Highway TrafficSafety AdministrationNHTSA
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National Transportation
Safety BoardNTSB
Noise, vibration and
harshnessNVH
,,
OxygenO2
On board diagnostics
OBD
On board diagnostics II
OBD II ,1996.
()
Outside diameterO.D.
Over Drive (transmission)
OD
()Original equipment
OE
Original equipment
manufacturerOEM
In an overhead cam engine (OHC), the camshaft is located in
the top ofthe cylinder head. Push rods are NOT needed to
operate the rockers andvalves. With the cam in head , the
number of valve train parts isreduced. Also the valves can
placed at an angle to improve breathing.The OHC increase highspeed efficiency and power output. The OHC can besingle
overhead cam SOHC, or dual overhead cam DOHC.
Over head camOHC
The unit of electrical resistance measurement. One ohm is the
resistance that will allow one ampere to flow when pushed by
one volt.(Resistance measuring unit)
ohm
()
Engines with the camshaft in the block are called Overhead
Valve (OHV) Engines.Over head valve
OHV ,(),
.
An off-road vehicle is considered to be any type of vehicle
which is capable of driving off paved or gravel surface.Off-Road Vehicle
ORV
Unit of pressure (1 Pa = 1 N/m2), (1 MPa = 1000,000 Pa = 1
N/mm2)Pascal
Pa(1=1/),(1=1000,000
=1/)PCM is a computer that manages engine and power train
systems. Withinengine management, the PCM is responsible forfuel delivery, ignitiontiming and some emission control devices.
Power control module
Powertrain control modulePCM
Positive crank casePCV
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ventilation
Port fuel injection
PFI
Plug-in Hybrid Electric
VehiclePHEV
This unit reduces the air pressure supply to the front axle of the
towing vehicle is de-coupled in order to reduce the braking
power andmaintain vehicle stability of the now much lighter
vehicle.
Pressure limiting valvePLV
Measure of air pollution. It is common practice to express the
quantity of a gaseous pollutant in the air as parts per million.Parts per million
ppm
()
Power split devicePSD
Pound per square inch
PSI (psi)
The power steering oil pressure switch is attached to the power
steering high-pressure tube and detects a power steering load.
When apower steering load is detected, it signals the ECM. The
ECM adjusts theidle speed for the increased load.
Power Steering Pressure
SwitchPSPS
photovoltaic
PV
Partial Zero Emission
VehcilePZEV
Symbol of electric chargeQuantity of electric charge
Q
RadialR(1)
Reverse
R(2)
RightR(3)
Ford's RABS or GM and DaimlerChrysler's RWAL; control
both rear wheels at the same time.Rear Anti-Lock Brake
SystemRABS
The microprocessor can both read and write data to each
memory location.Random access memory
RAM
RAV
RC is the number of minutes a fully charged battery at 80
degrees F(26.7degrees C) can be discharged at 25 amps until
the voltage fallsbelow 10.5 volts.
Reserve Capacity
RC
Remotely controlled racing carsRemotely Controlled
RC, R/C
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Run Flat TireRFT
Read only memory
ROM
Revolutions per minute
RPM (rpm)
Recreational VehicleRV
() GM and DaimlerChrysler's RWAL or Ford's RABS; controlboth rear wheels at the same time.
Rear Wheel Anti Lock brake
systemRWAL
Rear wheel driveRWD
SAE International (SAE) is a professional organization for
mobilityengineering professionals in the aerospace, automotive,
and commercialvehicle industries. The Society is a standards
development organizationfor the engineering of powered
vehicles of all kinds, including cars,trucks, boats, aircraft, andothers. Membership is open to the publicfor those particularly
interested in Human Factors and ErgonomicStandards.
Society of Automotive
EngineeringSAE
Is the amount that the spindle support arm leans in the top. SAI
isalso known as ball joint inclination BJI or king pin inclination
KPI
Steering axis inclinationSAI
()
Sensotronic Brake ControlSBC
Steer-by-wireSBW
Specific fuel consumption is equal to the mass rate of the fuel
consumption divided by the engine brake powerSpecific Fuel Consumption
SFC
Sequential fuel injectors
SFI
Spark Ignition
SI-1
SI-2
Spark Ignition DirectInjection
SIDI
Short-long arm suspension systemShort-long arm
SLA
The Sequential Manual Gearbox enables sporty, rapid gear
changesthrough all six gears via the steering wheel paddles or
selector lever,without the use of a clutch. Select Dynamic
Driving Control (Sportbutton) for faster engine response andeven more spontaneous drivingenjoyment.
Sequential Manual GearboxSMG
SOHC single overhead cam engine has one camshaft in
cylinder head, Cam act directly on valves or rocker arms can beSingle over head camSOHC
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used.
SRS means supplemental restraint system, and airbags fall into
thatcategory. So when you get in the new car and you see theletters SRSon your steering wheel, that's what it means. It
means you have airbagsin the car. Could be front impact airbags
that just come out of yoursteering wheel in the dashboard on the
passenger side. Newer cars haveairbags throughout the car. Side
curtain airbags, thorax airbags, frontairbags, back airbags.
Supplemental Restraint
SystemSRS
It is the calculation of a vehicle, at rest,rollover resistanceSSF
= T / 2 Hwhere, T is the "track width" of the vehicle and H is
the "height of center of center if gravity" of the vehicle.Thelower the SSF number, the more likely the vehicle is to rollover
in a "single-vehicle crash"
Static Stability FactorSSF
Special Service Tools
SST
Sport utility vehicleSUV
Carbureted and throttle-body injection engines have heated air
controls in the air cleaner. This is called a TAC.Thermal Air Cleaner
TAC
()
Most electronic automatic transmissions utilize a TCC
solenoid to lockthe torque converter electronically. Once
locked, the torque converterno longer applies torque
multiplication and will spin at the same speedas the engine
(assuming the converter is fully locked.)
Torque Converter Clutch
SolenoidTCC
Traction control system prevents wheels from spinning in
slipperyconditions by automatically cutting engine power,
lightly applying thebrakes or both.Traction control system
TCS(ASR)
Also ATDS , BTDC (after top dead center, before top dead
center)Top dead center
TDC
Thermal Efficiency
TE
This systemlet you know when you need to add air to your
tires. Thesesystems don't warn you until your tire has lost 25%of its pressure,the point at which danger may loom.
Tire pressure monitoringsystemTPMS
The throttle position sensor responds to the accelerator pedal
movement. This sensor is a kind of potentiometer that transforms
thethrottle position into output voltage, and emits the voltage
signal tothe ECM. In addition, the sensor detects the opening
and closing speedof the throttle valve and feeds the voltage
signal to the ECM. The ECMreceiving the signal from the
throttle position sensor determines idleposition of the throttle
valve. This sensor controls engine operationsuch as fuel cut. On
the other hand, the "Wide open and closed throttleposition
switch", which is built into the throttle position sensor unit,isnot used for engine control.
Throttle position sensorTPS
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Technical Service BulletinsTSB
This may also be known as an input speed sensor (ISS). This
sensorsends a varying frequency signal to the Transmission
Control Unit todetermine the current shaft speed of the input
shaft or torqueconverter. The Transmission Control Unit uses
this shaft speed todetermine slippage across the torque converter
and potentially todetermine the rate of slippage across the bands
and clutches.
Turbine Speed SensorTSS
The manifold heat control valve routs exhaust gas under the
floor ofthe intake manifold when the engine is cold. This is
improves thevaporization of the cold fuel. This is also called an
early fuelevaporation (EFE) vlave.
Thermal Vacuum SwitchTVS
()(Pollution control system) Also called PVS ported vacuum
switch. Thisprevents vacuum from operating the EGR valve
before the engine is wormedup.Thermal Vacuum Valve
TVV
Universal jointU-joint
()
This grading system, allows consumers to compare tire
treadwear,traction performance, and temperature resistance. Thefederal governmentrequires tire manufacturers to grade their
tires in these three areasand place the information on the
sidewall of the tire.
Uniform Tire Quality
Grading Uniform Tire
Quality Grading SystemUTQG
UTQGS
Unit of measuring electric potentialVoltV
Vehicle-to-grid (V2G) describes a system in which power can
be sold tothe electrical power grid by an electric-drive motor
vehicle that isconnected to the grid when it is not in use for
transportation.Alternatively, when the car batteries need to befully charged, the flowcan be reversed and electricity can be
drawn from the electrical powergrid to charge the battery.
Vehicle-to-gridV2G
Variable compression ratio is the technology to adjust internal
combustion engine cylinder compression. This is done toincrease fuelefficiency while under varying loads. Higher loads
require lower ratiosto be more efficient and vice versa. Variable
compression engines allowfor the volume above the piston at
'Top dead centre' to be changed. Thisneeds to be done
dynamically in response to the load and drivingdemands.
Variable Compression Ratio
EnginesVCR
Volumetric efficiency is the ratio of the volume of air drawn
into a cylinder to the piston displacement.Volumetric Efficiency
VE()()
().()
VDIM, Toyota's new system optimizes vehicle control by
adding newfeatureselectronically controlled brakes (ECB)
and electronic powersteering (EPS) and having them work in
concert with the stabilitycontrol (VSC), ABS, EBD and BA
Vehicle dynamic integrated
managementVDIM
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systems. Faster processing speed alsopromises more transparent
operation of the system.
Vehicle dynamic integrated
systemVDIS
Variable Geometry Intake
(manifold)VGI
The steering gear ratio will be changed in accordance with
vehicle speedVariable gear ratio steering
VGRS (1)
Variable gear ratio systemVGRS (2)
Vehicle identification
numberVIN
()
VRHS systems exist under many trade names, includingElectronic HeightControl (EHC), Active Height Control (AHC),
and pneumatic suspensionsystems. Depending on conditions
such as vehicle speed and terrain,Variable Ride-HeightSuspension (VRHS) raises or lowers the ride heightof the
vehicle while it is in motion. Some VRHS systems operate
automatically, while others require the driver to select the
appropriatemode. VRHS systems can have a favorable effect on
a vehicle'slikelihood to roll over because they lower the height
of the vehicle'scenter of gravity and improve its Static Stability
Factor (SSF) ratingfor highway driving.
Variable Ride-Height
SuspensionVRHS
Vehicle stability assist
VSA
The VSC is the brains of the hybrid car. It helps to manage
charging,drive assist, and engine starting functions. It shuts theengine downduring coasting and at stoplight to save fuel. It also
converts thetraction motor into a generator during braking to
help recharging thebatteries.
Vehicle system controlVSC (1)
VSC systems exist under many trade names, including
ElectronicStability Program (ESP), Electronic Stability Control(ESC), and VehicleStability Enhancement (VSE.)
Vehicle stability controlVSC (2)
ESP systems exist under many trade names, including Vehicle
StabilityControl (VSC), Electronic Stability Control (ESC), and
Vehicle StabilityEnhancement (VSE.)
Vehicle Stability
EnhancementVSC
The vehicle speed sensor is installed in the transaxle. It
contains apulse generator that provides a vehicle speed signal to
the speedometer.The speedometer then sends a signal to theECM
Vehicle speed sensorVSS
It is a valve train system developed by Honda to improve the
volumetricefficiency of a four-stroke internal combustion
engine. This systemuses two camshaft profiles and
Variable Valve Timing and
Lift Electronic ControlVTEC
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electronically selects between theprofiles. This was the first
system of its kind. Different types ofvariable valve timing and
lift control systems have also been producedby other
manufacturers (MIVEC from Mitsubishi, VVTL-i from Toyota,VarioCam Plus from Porsche, VVL from Nissan, etc). It was
invented byHonda R and D engineer Ikuo Kajitani. It can be
said that VTEC, theoriginal Honda variable valve control
system, originated from REV(Revolution-modulated valvecontrol) introduced on the CBR400 in 1983known as HYPER
VTEC
.
.
Variable Valve Actuation
SystemsVVA
Valve timing is adjusted on intake, and valves and there is theDualVVT-i engine, Valve timing is adjusted on both intake and
exhaust valves
Variable Valve TimingVVT
Variable Valve Timing with
intelligenceVVT-i
Variable Valve Timing and
Lift - IntelligentVVTL-i
Unit of power (1 W = 1 kg m/s), (1 W = 1 J/s)WattW
(1=1/)Wide open throttle (WOT) refers to an internal combustion
engine'smaximum intake of air and fuel that occurs when the
throttle platesinside the carburetor or throttle body are "wide
open", providing theleast resistance to the incoming air. In the
case of an automobile, WOTis when the accelerator is depressed
fully.
Wide Open Throttle
WOT
/
.().
Wheel speed sensorWSS
XUV: A crossover SUV (also called CUV for Crossover
Utility Vehicle) isan automobile with a sport utility vehicle
appearance but is built upona more economical and fuel-
efficient car-based platform.
Crossover Utility VehicleXUV
YZero emission vehicle
ZEV
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Symbols
g gravity
g
h height
h
l length, liter
l ,
m massm
p pressure
p
P power
P
t time
t
T torque
T
v velocityv
V volum
V
w weight
w
coefficient of friction
angular speed
pi
radius, density
stress strain
summation
, angle
sheer stress
efficiency
delta
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