Multimeter or Volt/Ohm Meter

Multimeter
A multimeter or Volt-Ohm Meter (VOM) is used to measure Voltage, Resistance (Ohms) or Current (amps or milliamps). Two types of meters are in common use. The analog or swing-needle Volt-Ohm meter displays test values according to the position of a needle on the meter face. A digital multimeter displays test values as numbers. The meters shown here and recommended are digital multimeters.

Accuracy is an important consideration when choosing a meter. Analog or swing-needle Voltmeters are generally rated for accuracy as a percentage of full-scale on the meter face. A typical analog meter may be rated as accurate to ±3% of full scale. Some analog meters offer 10-Volt and 50-Volt scales, with no range in between. For 12-Volt automotive electrical systems, this means testing on the 50-Volt scale, with a corresponding decrease in accuracy. On a 50-Volt scale, ±3% accuracy is equal to ±1.5 Volts. While still useful for testing circuits such as lights and horns, analog meters may not be accurate enough for use where precise measurements are required.

Digital multimeters or Digital Volt-Ohm Meter (DVOM) are preferred for precise measurement and for electronics work because most digital multimeters are more accurate then most analog meters. Another advantage of digital multimeters is that they are less likely to be misread, since there is no needle position to be misinterpreted or distorted by reading at an angle.

Perhaps the most important consideration is input impedance how much of a load the meter places on the circuit being tested. Meters with low input impedance place a greater load on the circuit because they allow more current flow through the meter. This can exceed design limits and be damaging to sensitive electronic components.

Most digital multimeters have very high input impedance 10 megohms (10,000,000 ohm) or higher-and make their measurements while allowing very little current flow through the meter. The meter itself is not a load in the circuit, and does not induce damaging current flow.

Digital Multimeter Kit, (US 1119, VAG 1526)

Digital Multimeter Kit:

Order Number: TU1 119 000 00 KTM
Used for monitoring electronic engine controls (Example: setting/checking the idle speed control system) and for general electrical troubleshooting.

NOTE: This tool has been superseded by the Fluke 83(R) Digital Multimeter. (US 1119 or VAG 1526 are still considered acceptable equivalents).

Fluke 83(R) Digital Multimeter

Digital Multimeter:

Order Number: TFL UKE 830 00 RSE
Used for monitoring electronic engine controls (Example: setting/checking the idle speed control system) and for general electrical troubleshooting.
- 10 Megohm input impedance
- ±0.3% DC Voltage accuracy
- Fully overload-protected

NOTE: This tool supersedes Special Tool US 1119 digital multimeter kit.