TSB : Automotive Terminology & Definitions

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ACTUATOR 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. AEMD (AUTOMOTIVE ELECTRIC DRIVE MOTOR) a U.S. Department of Energy program to develop low-cost traction drive motors for automotive applications. AIR BAGS 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. ALTERNATING CURRENT (A C) electrical current that flows in one direction, from positive to negative, and then reverses direction, from negative to positive. ALTERNATOR a belt driven device that provides electrical current for the vehicle's charging system. AMMETER an instrument for measuring the strength of electrical current flow in a circuit in terms of amperes. AMPERAGE the amount of electrical current flowing in a circuit. AMPERE (AMP) a unit for measuring the strength (rate of flow) of an electrical current. AMPLIFIER a device with electron tubes or semiconductors used to increase the voltage or current of a signal. AMPLIFY to enlarge or strengthen original characteristics. Usually used in reference to electronics. ANION negative ion. Alkali, molten carbonate, and solid oxide fuel cells are "anion-mobile" cells - anions migrate through the electrolyte toward the anode. 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. ARCING the ability of electrical energy to jump across an air gap. ARMATURE a laminated, soft iron core wrapped by wire that converts 11ectrical energy to mechanical energy. BATTERY ACID the sulfuric acid solution used as the electrolyte in a battery. BATTERY CELL 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. BATTERY SAVER 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. BATTERY a device that produces electricity through, electrochemical action. BENDIX DRIVE the starter drive gear that is attached to the starter motor armature and engages the gear teeth on the flywheel. BRUSH a bar of conductive material that rides on the commutator of a generator or motor. CAPACITOR a device, made up of two or more conducting plates, separated by an insulator, used to store an electric surge or charge of current. CATHODE 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. CATION positive ion. Phosphoric acid and proton exchange membrane (PEM) fuel cells are "cation-mobile" cells - the cation migrates through the electrolyte toward the cathode. CHARGING SYSTEM the system that supplies electrical power for vehicle operation and recharges the battery. CIRCUIT BREAKER a device used in an electrical circuit to interrupt current flow in the event of an overload or short. CIRCUIT a path through which electricity flows before returning to its source. COLD CRANKING AMPS the amount of cranking amperes that a battery can deliver in 30 seconds at O°F ( - 18°C). COMMUTATOR 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. CONDUCTIVITY transmission of electricity by metallic substances. Metals have high electrical conductivity, and with few exceptions, their conductivity decreases with increasing temperature. CONDUCTOR a material that provides a path for the flow of electrical current or heat. CONTINUITY the condition that exists in a working electrical circuit. A circuit that is unbroken, not open. CORRODE gradual loss from a metal surface from chemical action. CORROSION deteriorative loss of a metal as a result of environmental reactions. CORROSIVITY the characteristic of a material that enables it to dissolve metals and other materials or burn the skin. DELAYED ACCESSORY POWER 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. DIGITAL SIGNAL PROCESSING AUDIO SYSTEM 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. DIGITAL VOLT/OHMMETER (DVOM) an instrument that measures volts, ohms and amps and displays the results numerically. DIGITAL a voltage signal that uses on and off pulses. DISCHARGE the flow of current from a battery; to remove the refrigerant from an air conditioning system. DIVERSITY ANTENNA 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. DUTY CYCLE 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. ELECTRICITY 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. ELECTROCHEMISTRY science that deals with the relation of electricity to chemical changes and with the interconversion of chemical and electrical energy. ELECTRODE electrical terminal that conducts an electric current into or out of a fuel cell. ELECTRODE 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. ELECTROLYSIS 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. ELECTROLYTE chemical compound that conducts electricity from one electrode to the other inside a fuel cell. ELECTROLYTE a material whose atoms become ionized (electrically charged) in solution. In automobiles, the battery electrolyte is a mixture of sulfuric acid and water. ELECTROMAGNET an iron core surrounded by a coil of wire that temporarily becomes a magnet when an electric current flows through the wire. ELECTROMAGNETIC INDUCTION moving a wire through a magnetic field to create current flow in the wire. ELECTROMECHANICAL refers to a device that incorporates both electrical and mechanical principles together in its operation. ELECTRONIC pertaining to the control of systems or devices by the use of small electrical signals and various semiconductor devices and circuits. EMITTER in a transistor, the region or layer of semiconductor material from which electrons are injected into the base region. ENERGY the capacity for doing work and overcoming resistance. FIELD COIL a wire coil on an alternator rotor or starter motor frame; a field coil produces a magnetic field when energized. FLUX DENSITY 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. FLYWHEEL 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. FREQUENCY the number of cycles of a periodic waveform typically measured in one second intervals or hertz (cycles per second). FUSE a metal circuit protection device that melts when there is a circuit overload or short. FUSIBLE LINK 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. GENERATOR 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. GROUND CIRCUIT 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. GROUND a connecting body whose electrical potential is zero to which an electrical circuit can be connected. HALL EFFECT 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. HEAT SINK 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 HEADLAMPS 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. HIGH TENSION 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. HYDROMETER an instrument used to measure the specific gravity of a solution. IMPEDANCE the total resistance of an electrical device measured in ohms. INDUCTION 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. INSULATED CIRCUIT. a circuit that includes all of the high-current cables and connections from the battery to the starter motor. INSULATOR a non-conductive material used to insulate wires in an electrical circuit. INTEGRATED 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. ION CHROMATOGRAPHY a form of liquid chromatography that uses ion-exchange resins to separate atomic or molecular ions based on their interaction with the resin. ION atom that carries a positive or negative charge because of the loss or gain of an electron. KEEP-ALIVE MEMORY 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. LIGHT EMITTING DIODE (LED) a digital electronic display device which can be used as a simple signal light or arranged to show letters and/or numbers. LIQUID CRYSTAL DIODE (LCD) a digital electronic display device made of a special glass and liquid, which requires a separate light source. MAGNET any substance that attracts iron or an iron, steel or any ferrous metal alloy. MAGNETIC FIELD 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. MAGNETIC GAUGES electrical analog gauges that use magnetic forces to move the needle left or right. MAGNETIC PULSE GENERATOR a sensor used to monitor the position of any point on a rotating part such as a crankshaft or input shaft. MEMORY PROFILE SYSTEM 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 MEMORY part of a computer that stores or holds programs and other data. MERCURY SWITCH 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. MICROPROCESSOR the portion of a microcomputer that receives sensor input and handles calculations. MODULE an electronic control unit. MOTOR a machine that converts electrical energy into mechanical energy. MOTOR 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. OHM 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. OHMMETER an instrument that measures electrical resistance in ohms. OHM'S LAW 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. PARALLEL CIRCUIT a circuit with more than one path for the current to follow. PARALLEL CONFIGURATION 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. PERIOD in an electrical signal the period