自動車 用語 ２B[Back to Top]

B[Back to Top]
BCMAn acronym meaning Brake Control Module.

The computer that controls the anti-lock brake system, also know as the Electronic Brake Control Module or EBCM. See our section on Brake Service.


Belt slapA derogatory term for simply replacing a timing belt on a high milage engine, ignoring the water pump, seals and other components which also often fail around the same milage.

Please see our Detailed Topic All About Timing Belts for more details.


BleedingTerm which describes the process of removing trapped air from fluid. Often refers to brake bleeding or cooling system bleeding.


BottomingWhen a suspension travels to the maximum limit of it’s downward design. When jounce bumpers contact their mating surface. (See also jounce and rebound)
Brake jobAn obsolete and improper term. Often used to describe replacing certain brake components, with no regard to whether they are needed or will address the client’s problem.


Brake master cylinderA hydraulic pump attached to the brake pedal.

On pedal application it supplies hydraulic pressure into the system to apply the brakes.


Brake shudderA condition where the steering wheel moves side to side when braking and quits when the brakes are released.


Feels similar to improper wheel balance except braking brings it on rather than driving a certain speed.


ButcherA derogatory term for a person that regularly causes additional damage in the process of attempting a repair.

The act of damaging a component, by improper methods, that could have been properly repaired.




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C V BootAn acronym meaning Constant Velocity Boot. The flexible cover that protects the C V Joint by holding lubricant in and sealing contaminants out.


Often used on front wheel drive and independent suspension rear wheel drive vehicles.


(see also C V Joint)
C V JointAn acronym meaning Constant Velocity Joint.


A type of coupling that allows power to be transmitted to a wheel at a wide array of angles.


Often used on front wheel drive and independent suspension rear wheel drive vehicles.


(see also FWD and RWD)
Cabin filterA filter on the intake side of the air conditioner blower that protects the evaporator core from dirt build up.


Not all vehicles are equipped with cabin filters.



CamberThe angle formed by a line drawn through the vertical center of a wheel/tire and true vertical.


See also included angle and SAI
Certified used vehicleA marketing term for a late model, used vehicle that normally has an extended warranty tacked on to the price.


These may come from all the same places that any used vehicles come from (e.g., auctions, trade ins, repossessions, etc.)


They should be viewed with the exact same cautions as any other used vehicle.



Check engine lightAnother name for the Malfunction Indicator Light (MIL.) An indicator to the driver that a fault has occurred in the computer management system See our section onEngine Diagnostics.

(See also MIL)
ClunkerA derogatory term for any vehicle that is not still in the new car dealer’s inventory;


A vehicle on which the salesperson has already been paid their commission.


For instance, a “state of the art machine” becomes a clunker as soon as the sale is passed.


Clutch master cylinderA hydraulic pump attached to the clutch pedal.


On pedal application it supplies hydraulic pressure into the system to apply the clutch.

(See also slave cylinder)
Clutch slave cylinderA hydraulic cylinder that receives pressure from the master cylinder when pressure is applied to the pedal.


The hydraulic pressure is converted into movement that releases the clutch.


(See also clutch master cylinder)
CondenserA heat exchanger, normally located in front of the engine radiator.


The condenser is used to convert hot gaseous refrigerant to cooler liquid refrigerant.


This is accomplished by allowing air flow to remove the heat from the refrigerant.



Constantly variable transmissionA type of automatic transmission that uses a belt to transmit power rather than gears.


By varying the size of the drive pulleys the ratio is constantly varied and continuously delivered to the drive axles.


CoolantA mixture of anti-freeze and water used to cool the engine.

(See also Antifreeze)
COPAn acronym meaning coil on plug. An ignition system design where the ignition coil mounts directly to the spark plug and is fired by a low voltage signal.


CostThe initial amount paid, plus other expenses involved, divided by how long the product or service last.

(See also price and The Difference In Price and Cost in our AGCO Philosophy Category)
Counterfeit partsCheap substitute parts, often substandard, copied from OEM parts and represented to be OEM parts.


Often imported from countries with no enforcement of counterfeiting laws.

(See also OEM)
CrankWhen the starter motor causes the engine to turn in an effort to start.


Curb weightThe full weight of a vehicle, with all standard equipment and a full tank of fuel, but without passengers.


CVTAn acronym meaning Constantly Variable Transmission. (See Constantly variable transmission)
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DealershipAn organization that has purchased the rights to sell a certain line of new vehicles. The agreement also normally requires them to perform warranty work on those vehicles.


Dealerships often operate an auto repair shop and a parts store as part of their operation.


DetonationA rattling, pinging type noise, normally experienced on acceleration and under load. Left unattended engine damage can result. For more information see our Detailed Auto Topics Valve clatter, spark knock, pinging and pre-ignition.


(see also spark knock, pinging and labor knock)
DexronA type of automatic transmission fluid, widely used by General Motors and several other manufacturers, until recent years. Often mispronounced as dex-tron, there is no “T” in the name. Actual pronunciation is dex ron.


(see also Mercon and ATF)
Dog trackingWhen the front and rear wheels do not track in the same path causing the vehicle body to appear to travel in an angled path to forward motion.


Often the result of mis-aligned suspension, body or frame components.


DOTAn acronym meaning Department Of Transportation. A governmental body that regulates some safety aspects of vehicles.



DTCAn acronym meaning Diagnostic Trouble Code.


A combination of numbers and letters, stored by the vehicle’s computers to give an indication of the circuit in which a fault may be exist.


See our section on Engine Diagnostics and our Vehicle Questions Category for What do OBDII codes actually mean?


Dynamic balanceBalancing a wheel in both dimensions, side to side and from one face to the other.

Because wheels have width, they need balance not only from side to side but also from one side of the width to the other.


Dynamic imbalance normally manifest as a wobble from side to side, at higher speeds. (see also wheel balance, static balance and wheel weight)
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ECMAn acronym meaning Electronic Control Module.


ECM could describe any computer on the vehicle but is often used interchangeably with PCM or power control module.

(see also PCM)
EGRAn acronym meaning Exhaust Gas Recycle.


A system that cools the fuel air mixture in the engine, under certain conditions to help prevent pre-ignition.


For more information see our Detailed Auto Topics Valve clatter, spark knock, pinging and pre-ignition of.

(see also spark knock, detonation, pinging and labor knock)
Emergency brakeAn outdated term to describe the vehicle parking brake. In early days before vehicle hydraulic brake systems employed redundant design, mechanical emergency brakes were used.


In the case of brake failure they could be used to stop the vehicle. (see also parking brake)
Engine FlushA service often marketed to clean the engine crankcase. Very seldom actually needed and usually no more effective than more frequent oil changes. (see also wallet flush)
EPAn acronym meaning Extreme Pressure.

A lubricant that has been designed to withstand very heavy loading, often used in rear differentials. (see also viscosity)
EPDMAn acronym for Ethylene Propylene Diene Monomer, a very tough and flexible material, often used in construction of high-quality automotive belts and hoses.


EPDM is much tougher than neoprene and requires a different method of checking for wear, on belts.


For more information on EPDM belts, please see our Detailed Topic, Symptoms of A Bad Serpentine Belt and EPDM Belts.


ESCAn acronym meaning Electronic Skid Control or Electronic Stability Control. The vehicle is equipped with sensors that detect slide or slip. When detected the computer reduces engine power and combines with anti-lock braking to help maintain control.
EvaporatorA heat exchanger, normally located in the passenger compartment.


Used to remove heat from the passenger area, by absorption, using a low pressure gaseous refrigerant.


Expansion valveA mechanical device used to regulate the flow of liquid refrigerant into the evaporator core, thus helping to regulate the temperature of the core.


(see also orifice tube and evaporator core)
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Flash updateAn update to or replacement of computer software on the vehicle’s computer(s) performed by a repair shop.


Vehicles that support flash updates can be reprogrammed, using the proper type of scan tool and without replacement of parts.

Replacement computers must also be flashed after installation.


Flat rateA method of billing, where a predetermined amount of time is charged rather the actual time a repair takes to complete.

The time billed is often taken from a guide, known as a flat-rate guide. Express your opinion on flat rate pricing.


Flat rate techA technician paid a predetermined amount of time for a job, rather the actual time it takes to complete.

The time paid is often taken from a guide, known as a flat-rate guide. Express your opinion on flat rate pay methods.


FrameA vehicle construction technique where the body is bolted to a separate frame.

The frame provides the rigidity and an attachment points for suspension components, similar to the skeleton of the human body.


Very few cars but several trucks and SUV’s use frame type construction. (see also uni-body)
FWDAn acronym meaning Front Wheel Drive.


An arrangement where the front wheels are linked to the transmission and are used to propel the vehicle. (see also RWD)