The multimeter is an Automotive Shop Equipment Los Angeles used to check almost any circuit on the car, but caution must be used when selecting one for purchase. It should be an automotive meter of high impedance and preferably digital. A high-impedance meter is used to protect electronic circuits during testing. It will have two regular leads: a black and a red. Automotive multimeters have additional leads for temperature, engine speed, and other measurements exclusive to the automobile. The controls on most multimeters include selections for the three basic electrical measurements: voltage, current, and resistance. Some meters require the operator to select the range of measurements. The better and more expensive ones have automatic ranging. Ranging is the scale of measurement. For instance, if voltage is being read, the operator may have to select a 0-20-volt scale or a 20-100-volt scale. Automatic ranging meters do this automatically.
Automotive multimeters have selections for revolutions per minute, temperature, frequency, and others depending on the make and model of the meter. Additional leads are required to make the most of these measurements. There are meters that measure only resistance (ohmmeter), voltage (voltmeter), or current (ampere). Meters of this type are not common in the automotive field. There is one meter, however, that is common to almost every tire, parts, and repair facility. It is a volt/ampere tester. The VAT 40 is dated technology because it is an analog type of meter, butmany still exist and work as good as new. An analog meter is similar to the speedometer on a car where a moving needle points to a number for the measurement. Its replacement, the VAT 60 performs the same tests, but the display data is in a digital format. Both are used to test batteries and charging systems. This is one automotive meter that is capable of reading high current. On a starting system, the current may be as high as 400 to 500 amperes.
Most multimeters Automotive Shop Equipment Los Angeles can read no more than 10 amperes. None of the VAT testers will test a dead battery. There is a test with the VAT 40 that allows the battery to be charged for 3 minutes and then tested. This particular test does not mean the battery is good, but it can tell the technician if the battery will accept a charge. A battery should have at least 12 volts before testing to achieve a correct test result with a vat-40 or vat-60.