What is a Voltmeter?
Without a digital voltmeter, you will find it difficult or impossible to repair even the simplest electrical malfunctions on your vehicle. Attempting to repair an electrical fault without a voltmeter is like looking for a needle in a haystack. Analog voltmeters, test lights, and digital multimeters are inexpensive but essential tools every mechanic should have.
How does a Voltmeter Work?
All voltmeters and multimeters share a few basic functions, giving you the ability to read voltage and resistance on an electrical circuit. Many models also include a conductivity feature that beeps when there’s little resistance between the positive and negative leads.
A simplified version of the voltmeter is called a test light. Although a test light does not give you a voltage or resistance read, it will allow you to determine if a circuit is live or not.
How are Voltmeters Made?
If you’re feeling crafty, there are many tutorials online you may use to build a simple voltmeter at home. A homebuilt voltmeter is unlikely to be as inexpensive (or as rugged) as a store bought one, but you will learn a lot about how voltmeters work internally by constructing one yourself.
Why do Voltmeters Fail?
- Many voltmeters use AA or 9V batteries. If your voltmeter no longer works, try changing the batteries.
- Moisture finds its way inside the voltmeter’s plastic case. This fouls the sensitive electronics found in digital voltmeters.
What are the Symptoms of Failure?
- The voltmeter gives inaccurate readings. For example, you know your headlamp circuit works, but according to the voltmeter there’s no power running through the circuit.
- The voltmeter fails to power on.
What are the Implications of Failure?
- A malfunctioning voltmeter or multimeter complicates diagnostic and electrical repair work.
- You may end up chasing a non-existent electrical problem or fault because of a malfunctioning or broken multimeter.