– Hi everybody. I’m Matt Lewis withHagerty and in today’s DIY,I’m gonna talk about thebasics of using a multimeter. When you’re looking at multimeters,there’s a lot of different options. We’ve got very small pocket sized deals,very expensive professional tools,and then you can get in tojust the average multimeter. This one here is great because it’s gotall of the options you’re gonna needfor checking the electricalsystem on your automobile. A little multimeter like this isavailable in a lot of different places. You can find them at hardware stores,you can find them at auto part stores,you can even find them athome improvement storesor anywhere online. An item like this which isgreat for the DIY home use,$20-$25 it’s gonna doalmost everything youneed from a day to day usage. Now that we have our multimeter open,you can see there’s lots ofoptions as to what you can testand actually, moreconnections on the frontthan there are leads that come with it. We’re gonna be focusing on DC voltage,ohms or resistance, and amperage. Depending on what we’re testing,we’re gonna be plugging the leansinto these different terminals. We’ve only got one black terminal on hereso that’s obviously goingto be our ground lead. First thing we’re gonnabe working with is voltageso I’m gonna go ahead and plug it intothis one labeled voltage. For the sake of testing voltage,I’ve got a little batteryhere hooked up to these leads. Since there’s actually electricityat the end of these leads,I’ve put down some cardboard soour metal table doesn’t start conducting. With this multimeter,there are multiple options for voltage. What it does is it basically movesthe decimal point around here. We know that cars are 12 to 15 voltsdepending on the situation so our 20 voltmax setting is gonna be plenty forwhat we’re working withon the automobile here. You can move it up to 200 which yousee just jumps this decimal point,and even to 500 whicheliminates the decimal point. While you gain head room for voltage,you lose accuracy because you can’tsee portions of a voltat the 500 volt setting. At 20, we’re great. We know we’re not gonna exceed 20 voltsand we get plenty of accuracy withto the hundredths of a volt. I am gonna warn you that electric carsrun super high voltage,enough to be lethal. If you have an electric or a hybrid,I would advise just taking it to a shop. Don’t mess around with the electricalsystem on it because it is dangerous. When you’re testing voltage on a car,you’re gonna remember that thisblack lead is going to beyour negative terminal. That’s gonna be the ground. We’re gonna go ahead and hook itup to our pigtail here with the black. This red one is gonna bethe positive terminal. That, we’re gonna wannahook up to our positive. Here we see, this little battery Ihave is reading 13. 81 volts. That’s pretty normal for a 12 volt systemto actually read higher than 12 volts. A regular car battery’s gonna bebetween 12 and 13 if it’s functioningproperly with the car off. When the car’s running, yourcharging system kicks in,you might see anywhere from 14 to 15 voltsdepending on what your alternator orgenerator is currently doing. When we’re talking about voltage,what we’re actually looking at isthe electrical charge differencebetween the negative terminal of a batteryand the positive terminalof a battery or a circuit. A good analogy for thatis like water pressure. When you’re looking atthe water in your home,how much pressure does it have?Next thing we’re gonnatalk about is amperage. You can consider amperagelike the flow rate,so how much water is actuallycoming through the system. For amperage, I am gonna haveto move this terminal overfrom our voltage settingto our amperage settingjust like this and I’m gonna have toswing our dial over tothe DC 10 amps setting. This is gonna allow us to measureamperage instead ofvoltage on this circuit. When you go to measureamperage on a circuit,you do actually have todisconnect the circuitand put the multimeter in betweenthe power and the loador light in this case. I hooked up the red lead to the positiveand I’m gonna hook up the black leadto our red lead here which willcomplete our circuitand turn the light on. Pulling just over half of an amp. We’ve tested the voltage of our battery,we’ve tested the amperage of the circuitwith the light bulb on. The final setting we’re gonna talk aboutis this ohm or resistance setting. What that is is it measures how difficultit is for electricity topass through way circuit. When we’re looking at a littlepiece of wire like this,this is just copper wire,this should be almost zeroohms or zero resistance meaningit’s very easy for electricityto flow through it. If we go ahead and hookour terminals up here,once this settles we’re at . 3 ohms. This may just be a variance ofwhat the multimeter can read becausethis is a fairly inexpensive multimeter. It may be this does have a tinybit of resistance in it but,basically we’re looking for a verysmall number when you’re readingsomething like just a piece of wire. Right here I’ve got whatis an ignition coil,I believe it’s off of a little motorcycle,and measuring across these two points,we’re gonna see how easy it is forthe electricity to flow from side to side. We hook this up and we seeabout five and a half ohms. That’s more difficult for electricityto flow than just this pieceof wire but, still fairly easy. That’s not a lot of ohms. For the sake of testing all threethings we’ve talked about today,I’ve gone ahead and madeour light bulb broken. This light doesn’t function anymore. We hook power up to it. There’s no light. First thing we’ll test is voltage. We’ve got our voltage set back up,we’ll hook up to the negative terminaland positive terminal. Electricity is getting tothis point in the light bulb. Next thing we’ll test is amperage tosee if that electricity is actuallyflowing through the light bulb. Go ahead and switch that over to amperage,move our terminal overto the amperage terminal,and we remember we put the amperagein line with our circuit. Go ahead and hook this up. It’s reading nothing. I know that this circuitis not completing,meaning there’s somethingwrong inside the bulb. The final test we can do is our ohm test. We’ll go ahead and move this back to ohms. We’ll put our meter back on ohms. We’ll go ahead and hook thisup and it appears to be open. The meter didn’t even react. What that means is there is nothingconnecting this wire and this wireand that’s why the bulb’s not lighting up. Now we know we’re gonnaneed a new bulb in herebecause the electricity can no longerflow through it causing it to light. We can replace this bulb andjust see if we can fix it. For the sake of troubleshooting,what we’re gonna do is we’re gonnaactually measure theohms of this light bulb. The way you do this is thesebulbs, this is an 1157 bulb. It’s super common for cars. This outside ring hereis the negative terminaland then what you have istwo positive terminals. It’s called a dual filament bulb. If you look really close you can seethere’s actually two filament sections. Those are what produce the light. We’re still on our ohm setting sowe’re gonna go ahead andconnect to the negativeand then probe this positive. It didn’t even react when I hooked it up. There could be a couple of issues. These connectors here thathook the socket to the bulbmight be corroded or broken,this outside may no longer be groundingproperly to our negative terminal,or really where these wires go inmay be broken or kind of anywherewithin this circuit it may be broken. We grab a new bulb, we put it in. Now we can use the same ohmtest, hook up to our terminals. We’re seeing the numbers respondingwhich means electricity canflow through this circuit now. What that means is we have a good bulband a good housing with good wiring. Now that we’ve fixed it,if we hook our batteryup, we have light again. If you find yourself with a brand newmultimeter that you want to play with,you can do it with something assimple as a double A battery. Here we’ve got a positiveterminal labeled,it says it’s gonna be 1. 5 volts. You can hook that up and play with that. I hope this multimeter DIY was helpful. If you have any comments or questions,go ahead and post them below. Make sure to subscribe to our channelso you know wheneverwe put out a new videoand we’ll see you next time.
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