If you wanna be able to troubleshoot, diagnose, and fix anything that breaks in your RV, the No. 1 tool that you're gonna need is a multimeter. But these things can feel kind of intimidating, so today I'm gonna walk you through every test on this fancy meter and show you the ones that you can still do on this cheap harbor freight meter. I'm gonna show you what the test is, how to do it, and for each one, give you an activity that you can do in your RV to test out your multimeter skills. Today, my name is Emily. I'm a certified mobile RV repair tech based in Las Vegas. This is RV Repair Woman. You got this.

Voltage

If you wanna see an example of this technique, check out my "How to Troubleshoot Your Water Heater" video, where this is the exact technique I follow. But to complicate things just a little bit, there are two types of electricity and therefore two types of voltage test: AC and DC. So, when we're searching for Dora, we need to know whether we're looking for AC Dora or DC Dora. In all troubleshooting videos that RV Repair Woman makes, I'll talk you through each time whether you're looking for AC electricity or DC electricity. But just as a general rule of thumb, your 12-volt DC power comes from your batteries and that's gonna power your lights, your leveling jacks, your slides, and most of the circuit boards in your appliances. Whereas your 120-volt AC power is gonna come from either your shore power when you plug in or your generator or your inverter if you're boondocking. And that more powerful 120 volts is going to power your more power-intensive appliances. This is gonna include your air conditioner, your fridge if it's on electric, and your water heater if it's on electric and then of course, your outlets.

Then, to actually test for voltage, we need to plug our probes into our meter. On the simple meter, we're gonna plug our black probe into the black section, and we're gonna plug our red probe into the spot that has a V next to it. Pretty self-explanatory. On my simple meter, I just need to match up the colors. I don't need to worry about any extra places to put my red probe. Now, we're ready to test voltage around our RV. One thing we need to keep in mind when we're testing for voltage with a multimeter like this: we're actually testing for the difference in voltage across our probes. This sounds a little in the weeds, but stick with me. As a metaphor, think about if you were to measure my height standing on the floor, I'm about 5 foot 3. But if I were to stand on a bench, I would be roughly 6 foot 3 if we measured me from the floor. If we measure me from my knees, I might be closer to 4 foot 3. So, when it comes to measuring people's heights, we have all decided on a common place, the ground, that we're gonna measure their height from. When it comes to voltage, we need something similar, and in electricity, we call this place either the common or the ground.

A lot of the times, when we're measuring voltage, we're actually gonna put our black probe on the part of the RV's frame so that can be our ground that we're gonna measure the difference in voltage off of. This can look like a couple of different things: either finding a metal part of the RV frame to put your meter directly to, or a lot of times in appliances, there'll be a bunch of wires that all go to a metal screw that's drilled into the frame. We can put our black probe onto that to guarantee that we're on the ground. And then, we usually use our red probe to poke around in different parts of the circuit to find Dora.

Here's some activities you can do to try this out in your rig. Let's start with DC volts. Set your meter to DC voltage, and then unplug your RV from shore power. If you're staying at a park, go find your house batteries and place your black probe on the negative terminal of the battery and your red probe on the positive terminal of the battery. If you have lead acid batteries and they're fully charged, you should be seeing a reading in the realm of 12 and a half volts.

Now, keeping your red probe on the positive terminal of the battery, take your black probe and touch it to a metal part of the frame. You should still see 12 and a half volts. This is because if you were to follow the cable coming off of the negative terminal of the battery, it would eventually lead to a screw that is either bolted or screwed into the metal frame of the RV. That way, no matter what, the frame can act as our ground for all of our appliances. Then, go ahead and plug your RV back into shore power and test your batteries again. With your RV plugged in, you should be seeing a reading in the realm of 13 and a half volts if you have lead acid batteries. This is because your converter should be kicking in to charge your batteries. You're doing great.

While you're at the batteries, go ahead and put both of your probes on the positive terminal of the battery. Now, you're gonna see 0 volts, even though the batteries are charged. We just tested that. And that's because we're measuring the difference in voltage from one probe to the other. So, now that they're at the same point, there is no voltage difference. That's why the concept of finding your ground is so important.

If you want an activity to test AC volts, go ahead and set your meter to AC voltage, plug your RV into shore power, and head over to one of your outlets. If you put your probes here and here, you should see a number in the realm of 120 volts.

Amperage

Let's move on to our next test: Amperage. I use Amperage tests much less than I use voltage tests, so we're gonna go through this one much quicker. So, filming Emily did a pretty terrible job of explaining amperage at this point, so editing Emily is gonna come in to save the day.

How is the amperage test different than the voltage test? Well, with the voltage test, for the most part, we're looking to see: Did electricity make it to a certain component in the circuit? With the amperage test, on the other hand, we're looking to see how hard that individual component is working. So, if you remember back to the voltage test, there's going to be a value that we expect to see. It's either gonna be 12 and a half if we're on the DC side of things or 120 if we're on the AC side of things. When it comes to amperage, we're gonna get our expected value from a tech sheet that the appliance comes with. So, I can pull up the spec sheet for your appliance and see what amperage different components in it should be pulling. And I can compare that to the amperage reading of what I actually see. If the amperage reading is significantly higher or lower than the value that is expected according to the spec sheet, then we know that something is wrong and we can act accordingly from there. So, to review, for voltage, our expected readings are either 12 and a half or 120. For amperage, our expected reading is going to come from a spec sheet. And again, in future RV Repair Woman troubleshooting videos, I'm always gonna tell you which test you're looking for, just like with voltage, where we had AC volts and DC volts, we can also have AC amps and DC amps. So, how do we test for amperage using our multimeter? Well, this simple meter actually doesn't allow you to test DC amps. It only has a DC Amperage setting. But if we are gonna test for DC amps, we're gonna be looking at this section here labeled DC A for DC amps. And again, we have to tell this meter, because it's not very sophisticated, roughly what range of amperage we think we're going to see. For the most part, if you're ever running this test in your RV, the 10 amp setting is probably gonna be the way to go. On the simple meter, I need to move the red probe up to this point that's labeled for DC amps. On my fancier meter, I just move this dial again to A for amperage, and then use this orange button to select between AC amps and DC amps.

So, how do we actually test for amps? I'm back. So, running an amperage test with your probes on your multimeter is actually something that I don't think I have ever done in my professional life, either as an RV tech or as an illusion fabricator (that was my previous job). It's just not something you do very often for two reasons. One, unlike with the voltage test where we could just leave the circuit as it was and then just poke and prod in with our probes to run an amperage test, because we're trying to read the current going through the wire, we actually have to have our meter in line with a component in the circuit. So, the way I usually think about it is the... Was it Pepsi or Coke? The brand that had the "We Are the World," everyone holding hands? I'm sure some old person older than me can tell me in the comments which brand it was. My wonderful boyfriend has since informed me that it was neither Pepsi nor Coke, it was a separate charity thing. "We Are the World." I had combined the "I Just Wanna Buy the World a Coke" and the "We Are the World" campaigns in my head. Two separate things, mean takeaway. Imagine a long line of people all holding hands. That's the metaphor. But if we think of your circuit like a bunch of people holding hands, if we were to test the voltage across one person, we could put one probe on each side of a human and read the voltage going through that human. This is a metaphor, stick with. In order to read the amperage, we would need two people to let go and stop holding hands, and then put our meter in between those two people, and then have one person on each side hold the probes, and then we could read the amperage going through. What this looks like in real life is if you wanted to read the amperage with your probes, you would need to disconnect a component from the circuit, and then put one probe onto the terminal that you just disconnected from, and your other probe into the thing that you just disconnected. You can see we are recreating the connection that we just disconnected with the meter in between. But as I hope that you're able to sort of see with this, in order to get the probes where they need to be can be really difficult without shocking yourself, especially if we're on the 120 AC side of things. It's just physically difficult sometimes to get your meter in there, and then you have instances where several connections all come into one clip, like on this 9-pin connector in an air conditioner. There'd be no way that I could just disconnect, or you could, but it'd be really difficult, one of these wires from that 9-pin connection, and then get my meter in there, or I would have to take off the whole 9-pin connector and then only have power going to one of the pins. It's just not ideal. This is why I have never run an amperage test with my probes. It's just a pain in the butt, it can be difficult to do safely, and overall, just not something I recommend. One, I don't have to run an amperage test that often, and secondly, when I do, I prefer to use the amp clamp on my meter. Back to filming Emily, she'll explain why.

Instead, what I use is the amp clamp on my fancy meter. To use that, all I need to do is set my dial to amps, and then again, using the selector, decide whether I am testing for AC amps or DC amps. And then, all I need to do is put this adorable little mouth-looking part around a wire, and the internal computer in the multimeter is going to use a really cool property about electricity, and the fact that it makes an electromagnetic field when it goes through a wire, and it's gonna read that electromagnetic field and do some math to tell us the amperage going through the wire. This is so much more useful because I don't need to disrupt the circuit at all and unplug things. I can keep everything just the way it is, and then just wrap around whatever wire I need to test. If you wanted to go test AC amps in your RV right now, plug into shore power and set your fridge to electric. Then, open up this access panel, and you should see some wires coming out of a heating element that's going into a tube on your right. Set your meter for AC amps, put your amp clamp around one of those wires, and you should be seeing a reading in the realm of 2.7 amps. This tells us that your heating element is A-OK. Again, there's maybe three scenarios in an RV total that I can think of where I actually use the amperage test, but it's there, we talked about it, we're moving on.

Resistance

Onto resistance and continuity. What are these? Well, amperage and voltage were telling us about the electricity itself. Resistance is telling us about the material that the electricity is moving through, namely how hard it is for electricity to move through that material, and we measure resistance in ohms. So, we would expect a wire to have a reading pretty close to zero ohms because it's purposely very easy for electricity to move through a wire, whereas we would expect a hunk of wood, for instance, to have a close to infinity resistance reading because electricity doesn't like to move through dry wood. That's why we don't use it in circuits. Continuity breaks down this concept into a binary. So, the manufacturer of the meter chooses one resistance reading, and I believe for the Klein CL800, it's 50 ohms. So, they decide any reading under 50 ohms means that electricity can move through this material just fine, whereas any reading over 50 ohms means that electricity can't move through this very well. So, any reading under 50 ohms has continuity, and any reading over 50 ohms does not have continuity. But these are two separate tests. Sometimes, we wanna measure the actual resistance of a component in a circuit to see how well it's functioning, and other times, we just need the binary, "Can electricity move through this or not?" So, how do we test for resistance or continuity? Well, on the simple meter, they're separated. So, to test for resistance, I would need to move my meter somewhere into this section, which is labeled with the ohm symbol. And for the most part, most things you're gonna test in your RV, the 200-ohm section is probably gonna be your best bet. And then, if you wanna test for continuity, remember, that's the binary one, you're gonna move it over to this symbol, which has an auditory symbol. When you go to plug in your probes, you need to make sure that the red probe is plugged into the spot that has the ohm symbol next to it as well. And on my fancy meter, these settings are built into one. So, I just move my dial over to the one that has the auditory and the ohm symbol right next to each other. And then, I can use my orange button to cycle through whether I'm testing continuity, resistance, or a diode. We're just gonna ignore the diode setting for now. If you would like an advanced multimeter video, let me know in the comments, and we can talk about that one. I never use it. The reason why continuity is represented by the audio symbol is because when you touch your probes together, you get that really annoying beeping noise. That beep tells us when we have continuity. So, when I'm testing a component, if it has continuity, I'm gonna hear the beep. And if it doesn't have continuity, then I'm not going to hear the beep. This is super useful because sometimes, it can be really hard when you're testing a circuit and you need to use both hands to have your probe somewhere, and then also have the meter over here somewhere where you can see. It's just really nice that the meter tells you, "You got continuity." If you wanted to go play around with your continuity test, a great way to go do that is to go test all of the fuses in your fuse panel. I have a whole video here where I walk you through how to do that.

Hertz

At this point, we have reached pretty much all of the capability of this cheap Harbor Freight meter, but there's still several settings left on my fancier meter. So, I thought I would go through those now, rapid-fire style. The next setting on my meter is Hertz. This isn't a setting that I really ever use in RVs. People that specialize more in generators use it a little bit more often. Just for a brief explanation about what it is, if you remember from early in the video where I talked about how there are two different types of electricity, AC and DC, in DC electricity, the electrons are just moving in a straight line from one place to another. And that's how we get the electricity that's powering everything. In AC electricity, though, the electrons are actually wiggling in place very fast. The wiggle is the frequency. It's measured in Hertz. Hertz is the unit, similar to if you're measuring distance, the unit is inches. Here, we're measuring frequency. The unit is Hertz. Here in America, with our 120 volts AC, we're usually looking for a Hertz reading of around 60 Hertz. You can go test this by setting your meter to Hertz and then, whilst plugged into shore power, going to one of your outlets, putting one probe here and one probe here, and you should see a reading around 60 Hertz. Occasionally, with generators, this number can get a little out of whack. If your Hertz reading is drastically over or under 60, it means that we're creating a dirty type of electricity that can really muck up some appliances. Most of the time, you don't need to worry about this if you're someone that just plugs into shore power. But every now and again, generators specifically can get a little out of whack and start creating voltages that are not at that 60 Hertz.

The next test on my meter is capacitance, which is used to measure capacitors. Capacitors are used to store a bunch of energy so it can later be let out all at once. This can be really helpful in the start-up of some of our more power-intensive appliances. If we think of trying to push a car from a dead stop, it can take a lot of energy to get that car moving. But then once it is, one person can usually push a car on their own. The same is true for starting up some of our power-intensive appliances, namely the air conditioner and the fan inside of your air conditioner. So inside of your air conditioner is a capacitor that may or may not look something vaguely like this, and it is there to store up a bunch of power and then let it all out at once on startup to help get your air conditioner started. Capacitance is basically just a measure of how much oomph your capacitor has left. If you look on the side, it's gonna tell you what the capacitance reading for the capacitor should be, and then we can measure the capacitor to see how close it is to that reading to see if it's still good. I'm gonna make a whole separate video on how to do specifically because it is a pretty step-by-step process, and if you muck it up and get shocked, capacitors really pack a punch. They're probably not gonna actually do damage to you unless you have a heart condition, but wow is it gonna hurt. And I just wanna give that whole process its due and its own video just to give it the respect it deserves. Just know that's what that setting primarily is for and what is used most by RV repair techs.

Temperature

The next setting on here is pretty self-explanatory; it's for temperature. My meter came with a separate doohickey to plug in so I could test temperature with it. I honestly just have a separate thermometer that I use; I never use this setting.

LoZ

And then finally, we have this impedent setting, or what we just called in school the lozy setting, and this is basically a fancier version of the voltage setting that we talked about all the way at the beginning of this video. This low Z setting is just a voltage reading where it is scrubbing out any extra background noise that there might be to this voltage reading. Do not come for me, electricians, I am trying to simplify this for lay people. The main place that I use this low Z setting is when I'm testing the AC side of domestic air conditioners. The way they are wired, you can get wild readings if you just use the voltage setting, that can lead you down the wrong path when it comes to troubleshooting. So the only time that I use this setting is when I am testing the AC side of a domestic air conditioner.

I hope that this was helpful to somebody else out there. I'm gonna be referencing this video a ton in future "how to troubleshoot your RV" videos so that every video doesn't have to start with a multimeter tutorial. If you would like an advanced multimeter for your RV video, please let me know in the comments because I would love to talk about the range setting, the min-max setting, this cool little clip that you use on the side, and the fact that there's like a cool secret voltage tester built into this little nubin so that way you don't need to worry about the voltage difference between the two probes, you can just use this little nubin and just see is there 12 volts here, it's very fun. But I wanted to keep this video as short as possible. I know it's already wicked long. If you found this video helpful at all, please check out in the description, I have my ultimate guide to RV maintenance where I have an ebook that walks you through how to maintain everything from your roof to your air conditioner to your fresh water tanks and everything in between. This has been RV Repair Woman. You got this.