Technical HeadquartersAmerican Autowire’s Tech Tips, Terms, and FAQs

Technical Terms A-O

Ammeter -

An instrument-panel gauge used to measure flow rate of current into or out of the battery: It is calibrated in amperes for both charge (+) and discharge (-) rates, in ranges of 20, 30 or more amperes.

Ampere -

A measure of current flow.

Battery -

A cell or collection of cells that convert chemical energy into electrical energy. A reversible battery can be recharged by converting electrical energy into chemical energy. A battery has two poles- positive and negative. The amount of positive and negative charges is called potential.

Bulkhead Connector -

An OEM device used to connect wiring inside the car body with wiring outside the body. Usually located at bulkhead or firewall.

Circuit -

An electrical path from source (battery or generator), through load(s), and back to source. A typical circuit consists of a battery, wire, load (lamp or motor) and switch. See also Simple Circuit and Single-Wire Circuit.

Circuit Breaker -

A circuit-protection device, containing movable points that open if preset ampere load is exceeded. Some circuit breakers are self-resetting; others require manual resetting.

Coil -

1. Any electrical device or component consisting of wire loops wrapped around a central core. Coils depend on one of two electrical properties for operation, depending on application, either electromagnetism or induction. 2. Ignition coil.

Current -

This is the movement of electrons in the wire, also known as Amps. The greater the movement through the wire, the greater the number of amps.

Electron -

The basic unit of electricity. Think of electrons as “bullets”, moving through the wire. It is the movement of electrons which runs the devices.

Flasher -

The device that causes a turn signal or hazard warning system to turn on and off at regular intervals. Although turn and hazard flashers look alike, they are mechanically different and should not be interchanged. Hazard flashers are sometimes called heavy duty flashers.

Fuse -

A circuit-protection device, calibrated to melt at a predetermined amp level. It acts as the “weakest link” in the circuit, shutting off current before it can damage wires or components.

Fuse Panel (Fuse Block) -

A plastic or fiberboard assembly that permits mounting several fuses in one centralized location. Some fuse panels are part of, or contain, a terminal block.

Fusible Link -

A circuit-protection device, consisting of a conductor surrounded by heat-resistant insulation. The conductor is two gages smaller than the wire it protects, so it acts as the “weakest link in the circuit.” Unlike a blown fuse, a failed fusible link must be cut from the wire for replacement.

Gage -

A standard SAE designation of wire sizes, expressed in AWG (American Wire Gage). The larger the gage number, the smaller the wire. Metric wire sizes are expressed in cross-sectional area, expressed in square millimeters. Also spelled gauge: In this glossary, the spelling gage is used for wire size to help avoid confusion between this and instruction-panel displays, spelled gauge (below).

Gauge -

An instrument-panel display used to monitor engine conditions. Also spelled gage (above). A gauge with a moveable pointer on a dial or fixed scale is called an analog gauge. Those using only numerical readouts are called digital gauges. The driver must interpret the gauge reading to determine what action to take, if any.

Ground -

In a single-wire system, any metal part of the car’s structure that is directly or indirectly attached to the battery negative post. Used to conduct current from a load back to the battery. Self-grounded components are attached directly to a grounded metal part through their mounting screws. Components mounted to no grounded parts of a car require a separate wire running to a known good ground.

Halogen Lamp -

A specialty lamp that gives off a brilliant white light. Because of its high intensity, a halogen lamp is often used for fog lamps and driving lamps.

Harness -

A bundle of electrical wires. For convenience in handling and for neatness, all wires going to an area of a car are bundled into a harness.

Harness Clamp -

Plastic or rubber-coated metal fasteners used to attach harnesses to car underbody, frame or panels. Attached by screws or rivets.

Harness Clip -

Metal fastener that can be pushed onto edge of chassis rail to retain harness. Also called a frame clip.

Harness Ties -

Self-tightening nylon straps used to bundle wires into harness. Available in stock lengths that can be cut to size after installation. Once tightened, they cannot be removed unless cut from the harness.

Harness Wrap -

One of several materials used to bundle wires into manageable harnesses. See loom, split loom, loom tape and harness ties.

Indicator Lamp -

An instrument-panel display used to convey information or condition of the monitored circuit or system. Unlike warning lamps, indicator lamps are not used in critical situations. A headlamp high-beam indicator lamp is an example. See Warning Lamp.

Insulator -

Materials that do not conduct electrical current. Examples are cloth, glass, plastic and rubber. Wires for modern cars have plastic insulation.

Junction -

Any point from which three or more wires branch out in a circuit.

Lamp -

An electrical load designed to emit light when current flows through it. It consists of a glass bulb enclosing a filament, and a base containing the electrical contacts. Some lamps, such as sealed-beam headlamps, also contain a built-in reflector.

Load, electrical -

Any device that uses electrical current to perform beneficial work in a car’s electrical system. Lamps and motors are the two common types of loads found in a car.

Loom -

Harness covering, usually of woven material. Older cars used woven-cloth loom, most modern cars use a corrugated-plastic loom, or split loom.

Loom Tape -

A non-adhesive tape used as a harness wraps. Adhesive-type tapes, including electrical tape, are not recommended for wrapping harnesses. Often, a piece of shrink wrap is used at tape ends to keep tape from unraveling.

(OEM) Original Equipment Manufacturer -

A designation used to describe the equipment and parts installed in a car by the manufacturer, or those available from the car manufacturer as replacement parts.

Ohm -

The unit of electrical resistance is called an ohm. A solid copper core of #10 gauge wire 1000 feet long has a resistance of one ohm.

Ohmmeter -

A test instrument used to determine resistance in an electrical circuit. In auto electrical work, it is often used to determine the resistance various loads contribute to a circuit or system.

Ohm’s Law -

The electrical formula that describes how voltage, current and resistance are related. The basic formula is: E (electrical pressure in volts) = I (current flow in amperes) x R (resistance in ohms).