Recreational Vehicle (RV) Technician Practice Test

If the needle of a voltmeter deflects off the scale to the left, what should you do?

1. Reverse the test leads

2. Replace the voltmeter

3. Calibrate the voltmeter

4. Check the power source

The correct answer is: Reverse the test leads

When the needle of a voltmeter deflects off the scale to the left, it indicates that there is a reverse polarity connection occurring with the test leads. In this situation, the most appropriate action is to reverse the test leads. By doing so, you will realign the connections in such a way that current will flow in the correct direction, allowing the voltmeter to accurately measure voltage without going off scale. Replacing the voltmeter would not address the underlying issue, as it’s functioning correctly but is being used with incorrect lead orientation. Similarly, calibrating the voltmeter would be unnecessary when the problem is related to lead connection rather than the calibration of the device itself. Lastly, checking the power source may be useful in other contexts, but in this scenario, it does not resolve the immediate issue of reversed polarity indicated by the voltmeter’s behavior. Reversing the test leads directly rectifies the problem at hand, allowing for accurate voltage measurement.