Automotive electrical terms
Understanding automotive electrical terms will help you better understand how electricity is used in modern-day automobiles. Also understanding each individual term and its definition will aid in auto repair diagnosis of complex electrical systems. The first term to discuss is electrical current. This is the movement or the flow of electricity. The greater the number of electrons flowing past a given point in a given amount of time, the more current the circuit has. The unit of measuring electrical current is amps. This term is credited to Andre Ampere who studied this relationship between electricity and magnetism. The instrument used to measure electrical current flow in a circuit is called an ammeter. Automotive meters include this testing function.
In the flow of electricity, millions of electrons are moving past a given point at the speed of light. The electrical charge of any one electron is extremely small. It takes millions of electrons to make a charge that can be measured. For these reasons one amp of current means that 6.28 billion electrons are flowing past this point in one second. There are two types of current. Direct current or DC, and also alternating current or AC. With direct current the electrons flow in one direction only. In alternating current, the electrons change direction at a fixed rate forming a wave pattern. Typically an automobile uses AC from the alternator converted to direct current for charging the battery. And direct current to supply power to the important automobile systems. Most automotive meters will measure both types. Automotive electrical terms
Voltage is electrical pressure. Voltage does not flow like current. It is actually the pressure that causes the current to flow. To have current flow some force is needed to move the electrons down the wiring. This force or pressure within an electrical circuit can also be referred to as electromotive force or EMF. This electrical pressure is measured in units called volts. 1 V is the amount of pressure required to move one amp of current through a resistance of 1 ohm. Again an automotive meter has you covered for measuring voltage found in automobile circuits. An instrument called a voltmeter measures the voltage. The unit of measurement for electrical pressure was named after Allessandro Volta, who in 1800s made the first electrical battery.
When any substance flows it meets resistance. The resistance of electrical flow can be measured. The unit of measured resistance is called ohms. A German mathematics professor named George Ohm is credited with the discovery of resistance principles. A common symbol for an ohm looks like a horseshoe. Resistance is measured by an ohmmeter. This is why the standard automotive electrical tester is called a multi-meter. Yes this one tool can measure voltage, amps, and resistance or ohms. This is one of the most commonly used testers when performing any automobile system diagnosis. The equus automotive meter comes with a great instruction booklet that explains exactly how to use the tool. Definition of automotive electrical termsIn most cases when following a standard auto repair diagram, they will provide instructions to take voltage readings, resistance measurements and in some cases amperage readings. The results from your tests are compared to the factory specifications. Any results that are not within the specified range indicate a failure or malfunction of that system.
Example: if you have set a throttle position sensor code, 1 of the steps in diagnosis is to check for a 5 V reference signal at the sensor. If there is no 5 V reference at the sensor, Chances are, the TPS is okay. But more importantly, this gives you a clear path of diagnosis as a failure on the 5 V reference signal circuit. Following a wiring diagram for this circuit on your specific vehicle will uncover the problem.
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