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The Digital Voltmeter is the primary feature of the Power Probe 3 family, which consists of the Power Probe 3, Power Probe 3S, and the latest model, the Power Probe 3EZ. All of these circuit testers come with a built-in Digital Voltmeter, and the ability to supply Battery Voltage, and Ground. The Power Probe 3 family has a few other very useful features, but today, we’re talking about the Voltmeter. To truly use the Power Probe 3 series to their fullest potential, it may help to fully understand what the tools are trying to tell you.
In VDC mode, you have a digital voltmeter but is also a quick and easy polarity identifier. Since the tool is connected directly to the vehicle’s battery, it has the perfect reference for battery Positive (+) and battery Ground (-). If the probe tip detects voltage, within 0.5 volts of Battery Voltage, the tool considers that to be a GOOD voltage level and will notify the user with a RED LED, and a high-pitched tone. If the probe tip detects ground, with less than 0.5 volts present, the tool considers this to be a GOOD ground and will notify the user with a GREEN LED, and a lower-pitched tone.
In a perfect world, everything has good voltage and is properly grounded. However, in real life, there are Voltage-drops, Bad Grounds, damaged wires, corroded connectors, etc., etc. All these features in VDC mode work together to make finding these issues quick and easy.
When the Probe tip detects a voltage that is at least 0.5 volts below Battery Voltage, then the RED LED will not illuminate, and the high-pitched tone will not sound. What will show, is the voltage reading, in which case, a Voltage-drop has been identified. Similarly, on the Ground side, if the Probe-tip detects over 0.5 volts, then the GREEN LED will not illuminate, and the lower-pitched tone will not sound, in which case, a bad Ground has been identified. What will show, is a voltage reading that should not be present on a Ground connection.
To diagnose the above issues, the tool can apply the Battery-Supplied Voltage when a voltage drop is found. This will properly complete the circuit, as well as test the component. There is no need to condemn a component if a simple connection issue was to blame for poor performance. Similarly, on the Ground side, Battery Ground can be applied to a bad ground connection, in the same way, thus properly completing the circuit, and diagnosing the component. In most cases, the poor performance of an electrical component can be traced back to a connection issue.
With the Auxiliary Ground cable, Power Probes can supply Battery Voltage, and Battery Ground, simultaneously, thus completely activating a component, on or off the vehicle. You can test: lights, fans, relays, motors, actuators, etc., even before installing to a vehicle. There is nothing worse than installing a replacement window motor, only to learn that it is faulty after everything is installed. Now, replacement components, even used, can be installed with confidence.
These situations would be difficult to solve with a standard test light or just a Digital Multimeter. The VDC mode in the Power Probe 3 series will make diagnosing most electrical issues a breeze. The VDC is just one feature of the Power Probe tools. The Power Probe 3, 3S, and 3EZ have a few other very useful features that will be covered and broken down soon.