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Rear Axle

A part of the vehicle that connects both rear wheels to a center differential in a rear-wheel drive vehicle, or a crossbeam that connects both rear wheels and supports the rear of the vehicle in a front-wheel drive application.

Tune-Up

A regular maintenance, usually associated with the replacement and adjustment of parts and components in the electrical and fuel systems of a vehicle for the purpose of attaining optimum performance.

Oil Pressure

The amount of pressure created in an engine's oil system by the oil pump. A certain amount of oil pressure is needed to circulate oil throughout the engine and to maintain adequate lubrication. Low oil pressure or loss of pressure is dangerous because it can lead to expensive engine damage. A low oil level in the oil pan, oil leaks, dirty oil, diluted oil (with gasoline), too low a viscosity oil, a plugged oil pickup screen or oil filter, a worn oil pump or worn main bearings can all contribute to low oil pressure. Complete loss of oil pressure usually results from a broken oil pump drive shaft (if the pump is driven off the camshaft). Unless the engine is shut off immediately, it will be ruined.

Undercoating

The application of a sound-deadening and/or rust-inhibiting chemical, wax or sealer to the underside of a vehicle.

Battery

The battery is a storehouse of electrical energy for starting the engine. All cars and light trucks today have a 12-volt battery. Most are also maintenance-free, meaning you don't have to add water to them periodically. Some even have built-in charge indicators to tell you if they need charging. A green dot in the window means the battery is at least 75% charged, no dot means it needs recharging, and a clear or yellow window means you need a new battery because the water level inside is low. Don't try to jump start or charge such a battery.

Electrical System

The battery, wires and electrically operated accessories in a vehicle. The electrical system uses the battery and charging system as its power source, with wires and switches routing the voltage to where it's needed. The metal body serves as the ground or return path for the voltage back to the battery.

Refrigerant

The working agent in an A/C system that absorbs, carries and releases heat. The two primary types are R12 and R134a, but many other substances have similar properties (primarily a low boiling temperature) that allow them to be used as "alternatives".

National Highway Traffic and Safety Administration

This is the government agency that is responsible for making and policing safety rules for all vehicles. It is the agency that can order a vehicle manufacturer to issue a safety recall.

Exhaust Emissions

Toxic gases created when an engine burns gasoline, emitted in the form of unburned hydrocarbons, carbon monoxide and oxides of nitrogen.

APGS

Advanced Parking Guidance System

AC

Air Conditioning

Drive Train

All the moving components of the car as a whole including the engine, clutch, transmission, driveshaft, differential, axles and wheels.

Boots

Also called bellows, these are the protective rubber (synthetic or natural) or hard plastic (usually Hytrel) covers that surround CV joints. The boot's job is to keep grease in and dirt and water out. Split, torn or otherwise damaged boots should be replaced immediately. Old boots should never be reused when servicing a joint. Always install new boots.

Antifreeze

Also called coolant, is the colored fluid (usually green or red) found in your radiator. Antifreeze serves a few purposes. The most important and known is keeping the water in your radiator and engine from freezing in cold temps. It also keeps that same water from boiling over in the summer. Radiators are normally filled with a 50/50 mixture of antifreeze and water. The third function of antifreeze, or coolant is lubrication -- it lubricates the moving parts it comes in contact with, like the water pump.

Service Drive

Alternate term for the dealership's service department (specifically used to identify the front-end where advisors greet customers and inspect their vehicles). The shop is where the technicians actually work on the vehicles.

Intelligent Parking Assist System

An automatic system developed by Toyota Motor Corporation in 2004 to assists drivers in parking their vehicle.

Traction Control

An enhancement of an existing ABS system that prevents wheel spin while accelerating on wet or slick surfaces. It uses the same wheel speed sensors to monitor wheel speed during acceleration, but requires some additional control solenoids and a pump to apply braking pressure to control wheel spin. The traction control system brakes the drive wheel that's starting to spin to shift torque to the opposite drive wheel that still has traction.

Motorist Assurance Program

An organization that has developed voluntary uniform inspection guidelines and a code of ethics for the auto repair industry.

ABS

Antilock Braking System

Sensor

Any device designed to measure engine operating conditions or ambient pressures and temperatures. Usually electronic in nature and designed to send a voltage signal to an on-board computer, some sensors may operate as a simple on/off switch or they may provide a variable voltage signal (like a potentiometer) as conditions or measured parameters change.

GPS Navigation Device

Any device that receives signals for the purpose of determining the device's current location on Earth. The device provides latitude and longitude information, maps, directions (to a human in charge of a vehicle or vessel via text or speech or to an autonomous vehicle such as a robotic probe), information on traffic conditions (either via historical or real time data) to suggest alternative directions, information on nearby amenities such as restaurants, fueling stations, etc.

Overdrive

Any gearset in which the output shaft turns faster than the input shaft. Overdrive gears are used in most modern transmissions because they reduce engine rpm and improve fuel economy.

Aftermarket Component

Automotive replacement component provided by a company other than the original equipment supplier.

Clear Coat

Clear coat paint refers to the clear (non-pigmented) top coat paint that is applied over a colored base coat paint, and is found on most vehicles built in recent years. Clear coat paint increases the vehicle's paint durability, gloss and resistance to harmful environmental effects.

Tire Ratings

Coding system located on each tire used to identify width (a wider tire will give your car better grip on dry pavement), aspect ratio (how tall the sidewall is) and wheel diameter.

4WD

Four-Wheel Drive

NAV

GPS Navigation Device

Revolutions Per Minute

How the engine speed is often expressed

Powertrain

In a motor vehicle, the term powertrain or powerplant refers to the group of components that generate power and deliver it to the road surface, water, or air. This includes the engine, transmission, driveshafts, differentials, and the final drive.

Cylinder

In an engine, the round, straight-sided cavity in the engine block in which the piston(s) ride. Typically made of cast iron and formed as a part of the block.

Odometer

Instrument that measures and records the number of kilometers or miles a vehicle travels.

IPAS

Intelligent Parking Assist System

Advanced Parking Guidance System

Lexus's trademarked Intelligent Parking Assist System (IPAS)

LED

Light Emitting Diode

LCD

Liquid Crystal Display

MPG

Miles Per Gallon

Antilock Braking System

Modern systems that electronically monitor the speed of the wheels and regulate the hydraulic pressure accordingly. The aim is to maximize braking power while preventing the wheels from locking and skidding.

Four-Wheel Drive

A method of driving a vehicle by applying engine torque to all four wheels. Various schemes are used for 4WD including part-time, full-time and variable four-wheel drive. The primary advantage of four-wheel drive is increased traction-which is especially useful for off-road excursions or severe weather driving, but is of little practical value for normal driving.

Rear Wheel Drive

A method of driving a vehicle whereby engine power is applied to the rear wheels. Power from the engine flows through the transmission, down the drive shaft, through the differential to the rear axles and wheels.

Additive

A chemical added in small quantities to a petroleum product to improve certain chemical or physical properties.

Trouble Codes

A code number generated by a vehicle's onboard computer that corresponds to a specific fault. Most computerized engine control systems have a certain amount of self-diagnostic capability. When the engine is running and the computer detects a problem in one of its sensor or output circuits, or even within itself, it triggers a trouble code.

Front Axle

A crossbeam that supports the weight of the vehicle (typically a truck) and is connected to the spindles with kingpins.

Spark Plug

A device screwed into the combustion chamber of a spark ignition engine. The basic construction is a conductive core inside of a ceramic insulator, mounted in an outer conductive base. An electrical charge from the spark plug wire travels along the conductive core and jumps a preset air gap to a grounding point or points at the end of the conductive base. The resultant spark ignites the fuel/air mixture in the combustion chamber.

Shock Absorber

A device that converts motion into heat, usually by forcing oil through small internal passages in a tubular housing. Used primarily to dampen suspension oscillations, shock absorbers respond to motion; their effects, therefore, are most obvious in transient maneuvers.

Fuel Filter

A device that filters impurities from the fuel before it reaches the carburetor. Usually located near the carburetor in the fuel line coming from the fuel pump or inside the carburetor or fuel pump itself.

Defogger

A device that uses hot air or electrical heat to remove fog or ice from the inside and outside of the windshield.

StabiliTrak

A feature offered in General Motors' vehicles that provides enhanced safety in adverse driving and road conditions with a stability enhancement system.

Air Filter

A filter that prevents dirt and debris from air entering the engine.

Chassis

A general term that refers to all of the mechanical parts of a car attached to a structural frame. In cars with unitized construction, the chassis comprises everything but the body of the car.

Composite Headlight

A headlight system in which the bulb can be replaced without removing the whole unit.

Gasoline

A hydrocarbon fuel for use in internal combustion engines.

Gasket

A means of sealing the mating surfaces between various components. Gaskets are used between the various parts of the engine to keep oil, coolant, air and fuel in their respective places. Rubber, cork or combination cork/rubber gaskets are often used to seal the oil pan, valve covers, water pump and timing chain cover. Metal gaskets are used between the cylinder head and engine block, and metal or asbestos gaskets are used to seal intake and exhaust manifolds.

Knocking

A sound created by movement of parts in loose or worn bearings. Alternate definition: A noise caused by gasoline in the cylinders burning too quickly. Also known as detonation.

Differential

A special gearbox designed so that the torque fed into it is split and delivered to two outputs that can turn at different speeds.

Backup Camera

A special type of video camera that is produced specifically for the purpose of being attached to the rear of a vehicle to aid in backing up. Backup cameras are alternatively known as 'reversing cameras' or 'rear view cameras'.

OnStar

A subsidiary of General Motors that provides subscription-based communications, in-vehicle security, hands free calling, turn-by-turn navigation, and remote diagnostics systems throughout the United States, Canada and China. The services are only available currently on vehicles manufactured by General Motors and Saab Automobile. The service is available for all vehicles that have the factory-installed hardware.

Independent Suspension

A suspension system that allows each wheel on a vehicle to move up and down independently of the other wheels.

Air Conditioning

A system that cools and dehumidifies air entering the passenger compartment. The system uses a refrigerant to cool the air and carry heat away from the passenger compartment. Major system components include a compressor, condenser, evaporator, accumulator or receiver/dryer, and orifice tube or expansion valve. Do not intermix different types of refrigerants in an A/C system. Use the type specified by the vehicle manufacturer (R-12 for most 1994 & older vehicles, or R-134a for most 1995 and newer vehicles).

Rear Wheel Anti-Lock brakes

A term used by General Motors and Chrysler for rear-wheel antilock braking.

Stability Control

A type of advanced antilock brake/traction control system that uses the brakes to assist steering maneuvers and to help improve vehicle handling and stability as driving conditions change. The system includes various sensors that monitor the driver's steering inputs and the position of the body with respect to the road. A "yaw sensor" can tell if the vehicle is starting to understeer or oversteer in a turn. The stability control system is active fulltime and will apply individual brakes to create a counter-steer effect that brings the vehicle back under control.

Lock Nut

A type of hardware that is used to prevent another threaded component from loosening and backing off.

Twin I-Beam

A type of independent front suspension used on Ford pickup trucks that used two parallel I-beam axles (one for each wheel). The design combines the superior strength of an I-beam suspension with the flexibility and ride comfort of an independent suspension

Automatic Transmission

A type of transmission that shifts itself. A fluid coupling or torque converter is used instead of a manually operated clutch to connect the transmission to the engine. Newer automatics use electronic controls to regulate shifting and torque converter lockup.

Brake Job

A typical brake job includes replacing the brake linings (new disc brake pads and shoes), resurfacing the rotors and drums, adding fresh brake fluid and bleeding the system, and inspecting/replacing any other worn components (usually at extra cost). If rotors or drums are worn beyond safe limits, they can't be resurfaced and must be replaced. Leaky disc brake calipers, drum brake wheel cylinders or the master cylinder should be rebuilt or replaced.

Horsepower

A unit of measure for quantifying power output. Invented by James Watt, the term was originally used to describe how much effort was exerted when lugging coal out of a coal mine. One horsepower was the amount of effort one horse put forth in raising 33,000 lbs. one foot in one minute.

All-Wheel Drive

A vehicle (usually a car) where all four wheels are driven. Most are fulltime systems for year-round driving, and use a viscous fluid coupling center differential instead of a transfer case to route drive torque to all four wheels. This allows the front and rear wheels to turn at slightly different speeds when turning on dry pavement.

Miles Per Gallon

A vehicle's fuel economy is determined by a number of factors including the size of the engine, the type of carburetion used, the weight of the vehicle, the type of transmission used (manual or automatic), the final drive ratio, the size and type of tires used, tire inflation pressures, aerodynamic streamlining of the body, the driving habits of the driver, the kind of road surface and terrain upon which the vehicle is driven, the speed at which its driven, and environmental factors such as temperature, wind and humidity.

Check Engine Light

A warning light that comes on if the computerized engine control system detects an engine performance or emissions problem. Also called the "malfunction indicator lamp" (MIL). To determine the nature of the problem, the computer system must be accessed to read a fault code (see Diagnostic Trouble Code).

Severe Driving Conditions

Driving in stop-and-go traffic, frequent short trips, extreme temperatures, or towing and hauling.

MAP

Motorist Assurance Program

NHTSA

National Highway Traffic and Safety Administration

Radiator

Part of the cooling system that keeps the vehicle from having a meltdown. Coolant that has traveled through the engine is pumped through the tubes of the radiator and is cooled off for another round.

RWAL

Rear Wheel Anti-Lock brakes

RWD

Rear Wheel Drive

RPM

Revolutions Per Minute

Dynamometer

Special equipment used to determine an engine's horsepower rating. Usually expressed as so much "brake" horsepower aka the amount of horsepower the engine actually delivers after internal friction and parasitic loses are taken into account

Tire Rotation

Switching front tires to the rear and the rear to the front to ensure even wear.

Hydroplaning

The accumulation of water in a film under the footprint which causes a tire to lift from the road surface, losing traction. Hydroplaning is affected by vehicle speed, tread pattern, and water depth.

Hydraulic System

The delivery system of a modern braking set up. It uses fluid to transmit the force applied at the pedal to the wheel cylinders, where it can be converted back into mechanical energy to activate the brake shoes or disc calipers.

Rotor

The disc-shaped part of a disc brake assembly, upon which the brake pads bear; also called, brake disc.

Balance

The equal distribution of the mass of the tire and wheel assembly for smooth driving. Balance is achieved by fitting weights to the wheel rim to offset uneven weight distribution of the tire or wheel.

Oil Filter

The filter used to strain oil moving through the engine. These should be replaced when the oil is changed.

Lube Job

The greasing and lubrication of the suspension system, the drive train and other general parts of a vehicle. This should be performed professionally once or twice a year and can easily be done when a vehicle's in for other regular maintenance.

Service Writer/ Advisor

The individual at a garage or dealership responsible for writing repair orders, communicating them to the mechanic and estimating the final cost to the customer.

Motor Oil

The lifeblood of the engine, it not only lubricates the engine but also cools the crankshaft bearings and pistons. As an engine runs, combustion blowby into the crankcase contaminates this item with moisture, soot, and unburned fuel. Moisture is the worst culprit because it forms acids and sludge. Additives (nearly a third of the product is additives) fight the contaminants and give it special lubricating properties. However the item itself never wears out but the additives do. Requires regular maintenance to flush this product to replace the aditives.

Treadwear

The measure of the life of a tire tread.

Intake Manifold

The network of passages that direct air or air-fuel mixture from the throttle body to the intake ports in the cylinder head. The flow typically proceeds from the throttle body into a chamber called the plenum, which in turn feeds individual tubes, called runners, leading to each intake port. Engine breathing is enhanced if the intake manifold is configured to optimize the pressure pulses in the intake system.

Fuel Economy

The number of gallons of fuel used per 100 miles of driving.

Master Cylinder

The primary fluid pressurizing device in a hydraulic system. In automotive use, it is found in brake and, hydraulic clutch systems and is pedal activated, either directly or, in a power brake system, through the power booster.

Rustproofing

The process of applying rust-inhibiting chemicals, waxes or sealers to the underside and inside of the vehicle's body as well as any other rust-prone areas.

Octane Number

The rating number that indicates a gasoline's ability to resist knocking.

Tread

The region of a tire designed to contact the ground. It is molded of tough rubber for high traction and low wear.

True Rotors

The resurfacing of rotors (basically a brake job minus the brake pads).

Jump Start

The use of jumper cables to start a disabled car.

Ignition System

The various components that control the igniting of fuel in the engine's cylinders. The ignition system has two parts: the primary side (the distributor and electronic control module), and the secondary side (the ignition coil, distributor cap, rotor, spark plug wires and spark plugs).

Vehicle Identification Number

Unique serial number used to identify automobiles.

VIN

Vehicle Identification Number

Gear

Wheel-shaped parts with teeth cut into the edge. When one gear engages another, the second gear drives the other to transmit power.

Liquid Crystal Display

is a type of electronic display that forms opaque or dull-colored letters or numbers on various backgrounds. They are popular for digital dashboards, but they are not as readable in direct sunlight as other displays.

Light Emitting Diode

is an electronic light bulb of sorts that produces colored light. Used in the center high mounted stop light on many vehicles, and used as indicator lights in some instrumentation. They're also used in some vehicle speed sensors and in some electronic ignitions