Automotive Terminology & Definitions

a control device that delivers mechanical action in response to a vacuum or electrical signal; anything that the engine control computer uses to do something, such as trigger fuel injection or fire a spark plug. Most actuators on a computercontrolled engine system are activated by grounding their circuits rather than by actively powering them, since that protects the computer from short circuits.

a U.S. Department of Energy program to develop low-cost traction drive motors for automotive applications.

air bags are fabric bags that are filled quickly with a gas to provide supplemental protection for vehicle passengers during some collisions. Side-impact air bags are becoming increasingly available. Air bags are most effective in protecting vehicle occupants who are properly belted.

electrical current that flows in one direction, from positive to negative, and then reverses direction, from negative to positive.

a belt driven device that provides electrical current for the vehicle's charging system.

an instrument for measuring the strength of electrical current flow in a circuit in terms of amperes.

the amount of electrical current flowing in a circuit.

a unit for measuring the strength (rate of flow) of an electrical current.

a device with electron tubes or semiconductors used to increase the voltage or current of a signal.

to enlarge or strengthen original characteristics. Usually used in reference to electronics.

negative ion. Alkali, molten carbonate, and solid oxide fuel cells are "anion-mobile" cells - anions migrate through the electrolyte toward the anode.

one of two electrodes in a fuel cell or battery. The anode, the negative post of the fuel cell, conducts the electrons that are freed from the hydrogen molecules so that they can be used in an external circuit. It has channels etched into it that disperse the hydrogen gas equally over the surface of the catalyst.

the ability of electrical energy to jump across an air gap.

a laminated, soft iron core wrapped by wire that converts 11ectrical energy to mechanical energy.

the sulfuric acid solution used as the electrolyte in a battery.

the part of a battery made from two dissimilar metals and an acid solution. A cell stores chemical energy to be used later as electrical energy.

the battery saver system is an effective way to prevent complete battery discharge when the engine is shut down. Based on the preset time-limit, the system automatically disconnects the battery load when the battery is not being charged. Depressing the reset push button will enable the battery to be reconnected for additional periods of time. Critical systems can be set up to have battery power maintained.

a device that produces electricity through, electrochemical action.

the starter drive gear that is attached to the starter motor armature and engages the gear teeth on the flywheel.

a bar of conductive material that rides on the commutator of a generator or motor.

a device, made up of two or more conducting plates, separated by an insulator, used to store an electric surge or charge of current.

one of two electrodes in a fuel cell or battery. The cathode, the positive post of the fuel cell, has channels etched into it that distribute the oxygen to the surface of the catalyst. It also conducts the electrons back from the external circuit to the catalyst, where they can recombine with the hydrogen ions and oxygen to form water.

positive ion. Phosphoric acid and proton exchange membrane (PEM) fuel cells are "cation-mobile" cells - the cation migrates through the electrolyte toward the cathode.

the system that supplies electrical power for vehicle operation and recharges the battery.

a device used in an electrical circuit to interrupt current flow in the event of an overload or short.

a path through which electricity flows before returning to its source.

the amount of cranking amperes that a battery can deliver in 30 seconds at O°F ( - 18°C).

a slotted ring located at the end of the armature of a generator or motor. The commutator provides the electrical connection between the armature and brushes.

transmission of electricity by metallic substances. Metals have high electrical conductivity, and with few exceptions, their conductivity decreases with increasing temperature.

a material that provides a path for the flow of electrical current or heat.

the condition that exists in a working electrical circuit. A circuit that is unbroken, not open.

gradual loss from a metal surface from chemical action.

deteriorative loss of a metal as a result of environmental reactions.

the characteristic of a material that enables it to dissolve metals and other materials or burn the skin.

delayed accessory power continues electric power temporarily to certain convenience features after vehicle power has been turned off. For example, the feature allows the customer to close a window without reinserting the key. Delayed accessories include radio and power windows, power moon roof and message center.

a Digital Signal Processing (DSP) system modifies audio signals digitally to achieve better control of sound quality. DSP can be used for standard functions such as volume, balance, fade and tone control, as well as AM and FM stereo decoding. It also allows advanced audio processing such as concert hall emulation, sound shaping and adaptive noise reduction filtering.

an instrument that measures volts, ohms and amps and displays the results numerically.

a voltage signal that uses on and off pulses.

the flow of current from a battery; to remove the refrigerant from an air conditioning system.

a diversity antenna system uses two antennas mounted at different locations on the vehicle and automatically chooses one that provides the better FM radio signal.

a signal that varies the ratio of on time to off time, resulting in a square wave that can range between zero and 100 percent or may be high or low, and off may be high or low; in a process, the ratio of on time to total cycle time; in fuel injectors, the percentage of on-time to total cycle time; in solenoids, the percentage of on-time to total cycle time.

electric current used as a power source. Electricity can be generated from a variety of feedstocks, including oil, coal, nuclear, hydro, natural gas, wind, and solar. In electric vehicles, onboard rechargeable batteries power electric motors.

science that deals with the relation of electricity to chemical changes and with the interconversion of chemical and electrical energy.

electrical terminal that conducts an electric current into or out of a fuel cell.

a terminal that conducts an electric current into or away from the conducting part of a circuit, such as the terminal of a battery; firing terminals found in a spark plug.

chemical and electrical decomposition process that can damage metals such as brass, copper and aluminum in the cooling system; the decomposition of an electrolyte by the action of an electric current passing through it.

chemical compound that conducts electricity from one electrode to the other inside a fuel cell.

a material whose atoms become ionized (electrically charged) in solution. In automobiles, the battery electrolyte is a mixture of sulfuric acid and water.

an iron core surrounded by a coil of wire that temporarily becomes a magnet when an electric current flows through the wire.

moving a wire through a magnetic field to create current flow in the wire.

refers to a device that incorporates both electrical and mechanical principles together in its operation.

pertaining to the control of systems or devices by the use of small electrical signals and various semiconductor devices and circuits.

in a transistor, the region or layer of semiconductor material from which electrons are injected into the base region.

the capacity for doing work and overcoming resistance.

a wire coil on an alternator rotor or starter motor frame; a field coil produces a magnetic field when energized.

the degree of concentration of the magnetic lines of force that emanate from a magnetic sensor; when the tooth of a reluctor aligns with the sensor tip, the magnetic lines of force are squeezed together, which increases flux density.

a mechanical battery that stores kinetic energy. A flywheel is essentially a spinning wheel with a motor. Flywheels can be more responsive than chemical batteries, and they are less susceptible to the effects of weather.

the number of cycles of a periodic waveform typically measured in one second intervals or hertz (cycles per second).

a metal circuit protection device that melts when there is a circuit overload or short.

a smaller gauge wire that is included in an electrical circuit to provide circuit protection. The smaller gauge wire will melt when the circuit is overloaded.

a device that converts mechanical energy into electrical energy; SAE J1930 nomenclature for an alternator; a generating device that uses diode rectifiers to convert ac to dc.

that part of the circuit that is connected electrically to the negative terminal of the battery. Every electric circuit has a power and ground side. Most computer actuations consist of completing the ground side of an actuator's circuit; this protects the computer from short circuits. Resistance in a ground circuit will reduce the current through it and cause deterioration in the function of the circuit.

a connecting body whose electrical potential is zero to which an electrical circuit can be connected.

when current flows through a thin wafer of semiconductor material, and a magnetic field crosses it at a right angle, a voltage known as a Hall effect voltage will be generated at the edge of the material. Interrupting the magnetic field turns off the voltage. This is the principle used by Hall effect sensors.

part of a system designed to be at a lower temperature than its surroundings, used to dissipate heat from that system; device to dissipate heat and protect parts.

high intensity discharge (HID) headlamps provide a brighter, whiter light for increased forward visibility. They produce about 2 times as much light as conventional halogen bulbs and have a distinct appearance. Also, they are more durable than filament bulbs and require 37 percent less power to operate.

that part of a system that operates under or carries high voltage; in an ignition system, voltages in the secondary circuit of the system as opposed to the low, primary circuit voltage.

an instrument used to measure the specific gravity of a solution.

the total resistance of an electrical device measured in ohms.

the process by which an electric or magnetic effect is produced in an electrical conductor or magnetic body, when it is exposed to variation of a field of force. Induction is the principle used in an ignition coil to increase voltage.

a circuit that includes all of the high-current cables and connections from the battery to the starter motor.

a non-conductive material used to insulate wires in an electrical circuit.

an electrical circuit containing many interconnected amplifying devices and circuit elements formed on a single body or chip of semiconductor material; diodes, transistors and other electronic components mounted on semiconductor material and able to perform numerous functions.

a form of liquid chromatography that uses ion-exchange resins to separate atomic or molecular ions based on their interaction with the resin.

atom that carries a positive or negative charge because of the loss or gain of an electron.

a series of vehicle battery-powered memory locations in the microcomputer that store information on input failure, identified in normal operations for use in diagnostic routines; adapts some calibration parameters to compensate for changes in the vehicle system.

a digital electronic display device which can be used as a simple signal light or arranged to show letters and/or numbers.

a digital electronic display device made of a special glass and liquid, which requires a separate light source.

any substance that attracts iron or an iron, steel or any ferrous metal alloy.

the areas surrounding the poles of a magnet which are affected by its forces of attraction or repulsion; the region of space in which there is a measurable magnetic force.

electrical analog gauges that use magnetic forces to move the needle left or right.

a sensor used to monitor the position of any point on a rotating part such as a crankshaft or input shaft.

the Memory Profile System offers different drivers the ability to set into memory their preferred positions for several comfort and convenience features. A driver is identified by a unique key fob or entry code, and the vehicle systems automatically adjust to his or her settings. Depending on the vehicle, some of the following features can be included in the memory profile: Seat position Steering wheel position (tilt/telescope) Mirror positions Safety belt "D" ring height Pedal positions Radio stations Power steering assist level Ride firmness

part of a computer that stores or holds programs and other data.

a type of switch that uses the flow of liquid metal, Mercury, to complete the electrical circuit. Mercury switches are frequently used to control trunk and underhood lights.

the portion of a microcomputer that receives sensor input and handles calculations.

an electronic control unit.

a machine that converts electrical energy into mechanical energy.

in an HEV, an electric traction motor converts electrical energy from the energy storage unit to mechanical energy that drives the wheels of the vehicle. Unlike a traditional vehicle, where the engine must "ramp up" before full torque can be provided, an electric motor provides full torque at low speeds. This characteristic gives the vehicle excellent "off the line" acceleration.

a unit of electrical resistance of a circuit in which an electromotive force of one volt maintains a current of one ampere, named after German physicist Georg Ohm.

an instrument that measures electrical resistance in ohms.

a basic law of electricity expressing the relationship between current, resistance and voltage in any electrical circuit. Ohm's law states that the voltage in a circuit is equal to the current multiplied by the resistance.

a circuit with more than one path for the current to follow.

a hybrid electric vehicle (HEV) with a parallel configuration has a direct mechanical connection between the power unit and the wheels, as in a conventional vehicle, but also has an electric motor that drives the wheels. For example, a parallel vehicle could use the power created from an internal combustion engine for highway driving and the power from the electric motor for accelerating.

in an electrical signal the period is the amount of time it takes for one cycle of an electrical signal to repeat itself; the number of periods that occur in one second is the frequency of the signal.

any point or points of parallel movements or oscillations, in or out of synchronization; the rotational positions of the U-joints and yokes in a driveline.

photovoltaic panels contain cells that convert sunlight into electricity. While solar-powered vehicles are not currently feasible for production, solar panels could be used to power vehicle components, such as a fan to exhaust hot interior air when the vehicle is parked in the sun or to recharge the vehicle battery. Photovoltaic panels can be integrated into the hood, roof, sunroof, deck lid or spoiler.

a weak, permanent magnet-and-wire assembly which forms a position sensor.

a sensor that generates voltage from physical shock or motion, a knock sensor.

the condition of being positive or negative relative to a reference point or object; the particular state (positive or negative) with reference to the two magnetic poles.

a device that changes voltage by varying its internal resistance.

a set of instructions or procedures that a computer must follow when controlling a system.

eIectronic control of a solenoid that rapidly cycles it on and off many times per second in order to achieve a specific output.

the length of time during which a circuit is energized.

a type of memory used in a computer to store information temporarily.

a type of memory used in a computer to store information permanently, as opposed to the temporary storage provided by random-access memory (RAM).

a device that changes alternating current (AC) into direct current (DC).

to change one type of voltage to another.

a voltage signal generated by the crankshaft position sensor (or distributor, or camshaft position sensor - all equivalent components for this purpose). The voltage signal is sent to the computer as a fixed number of degrees BTDC for each cylinder, with the signal for cylinder No.1 distinguishable from the signal for the others.

the voltage supplied by the system computer to certain sensors. The sensors reduce the voltage by a specific amount, according to their function, and send the signal back to the computer. The computer then uses the reduced voltage signal to interpret the information sent.

an electromagnetic switch that uses low amperage current to control a circuit with high amperage.

in an electronic ignition, the trigger wheel mounted on the distributor shaft that triggers the pickup coil, which in turn signals the control module to fire the coil.

the Remote Lighting System removes the sources of light from the lamp fixture. Instead, light for all fixtures is generated from a single "light battery". Light is transmitted to the various fixtures and accessories via fiber optics or light pipes. The advantages of remote lighting include reduced power consumption, greater durability and more flexibility in packaging and styling lamp fixtures.

the opposition offered by a substance or body to the passage of electric current through it.

an electrical device installed in a circuit to lower voltage and current flow.

a variable resistor used to control current flow in a circuit.

point at which current flowing through a coil or wire has built up the maximum magnetic field.

a material that is neither a good conductor of electricity nor a good insulator.

any mechanism by which the engine control computer can measure some variable on the engine, such as coolant temperature or engine speed. Each sensor works by sending the computer a signal of some sort, a coded electronic message that corresponds to some point on the range of the variable measured by that sensor.

a circuit that has only one path for current to follow.

some hybrid electric vehicles (HEVs) use a series configuration, in which the heat engine or fuel cell together with a generator produce electricity for the battery pack and electric motor. Series HEVs have no mechanical connection between the hybrid power unit and the wheels; this means that all motive power is transferred from chemical energy to mechanical energy, to electrical energy, and back to mechanical energy to drive the wheels.

a circuit that combines series and parallel circuits.

a condition that occurs in an electrical circuit when the current bypasses the intended load and takes a path with little or no resistance, such as another circuit or ground.

an alternate path through which electrical current or fluids may flow.

a coil of wire that becomes an electromagnet when current flows through it. It then loses its magnetism when the current flow is turned off. The solenoid contains an iron plunger inside the wire coil that is spring loaded to one position. When the solenoid is energized, the plunger moves to the other position.

an electrical device with no moving parts.

the ratio of the weight or mass of the given volume of a substance to that of an equal volume of another substance, e.g. - water for liquids and solids; air or hydrogen for gases, are used as standards.

to join or unite by weaving, binding, soldering, cementing, etc., usually at the ends of two objects.

voltage fluctuations of different shapes in an electric circuit. The square wave goes immediately from one voltage to the other; the sine wave gradually changes, going through the intervening values. An electromagnetic pulse generator like a wheel speed sensor or a reluctor-type distributor pickup produces a sine wave. Hall Effect sensors, photoelectric switches, and other on-off signal generators produce square waves. For many purposes, square waves are easier for computers to work with, so on many vehicles there are electronic devices to modify sine waves into square waves.

the electric motor that is used to start an engine.

a device located between the impeller and turbine in a torque converter. It contains specifically angled blades around both sides of its circumference to redirect the flow of fluid coming off the turbine, which increases the force of the fluid driving the turbine, resulting in torque multiplication.

an electric motor that can move to a specific position on its range of travel.

a device used to open, close or direct the current in an electrical circuit.

a temperature sensitive variable resistor in which the resistance decreases as its ternperature increases.

a device that changes a force into an electrical signal.

device that converts variations in one energy form into corresponding variations in another, usually electrical.

an electronic device produced by joining three sections of semiconductor materials. Used as a switching or amplifying device.

ultracapacitors are higher specific energy and power versions of electrolytic capacitors-devices that store energy as an electrostatic charge. They are electrochemical systems that store energy in a polarized liquid layer at the interface between an ionically conducting electrolyte and a conducting electrode. Energy storage capacity increases by increasing the surface area of the interface. Ultracapacitors are being developed as primary energy devices for power assist during acceleration and hill climbing, as well as recovery of braking energy.

a magnetic sensor that generates its own alternating current voltage based on the interference of a moving object across its tip.

a resistor that can be adjusted so the amount of resistance produced in the circuit changes.

unit of electromotive force. One volt of electromotive force applied steadily to a conductor of one-ohm resistance produces a current of one ampere.

voltage lost by the passage of electrical current through resistance.

a device used to control the output of an alternator or generator.

an instrument used to measure voltage in a circuit.

a unit of measurement of electrical power. One volt multiplied by one amp equals one watt.

a silicone diode that allows current to flow in the opposite direction, once an applied voltage reaches a certain level.