The Trainer #84: How You Can Measure Voltage When Your Meter Leads Say You Shouldn't

#voltagedrop #automotiveelectricaltroubleshooting #electricaldiagnosis #multimeter #voltmeter
Probably the most confusing meter reading you'll ever see is voltage when your meter is connected to a ground at both ends.
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Due to factors beyond the control of Motor Age, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. Motor Age magazine (UBM Americas - Automotive Group) assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. Motor Age recommends safe practices when working with power tools, automotive lifts, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this video. Due to factors beyond the control of Motor Age, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Any injury, damage or loss that may result from improper use of these tools, equipment, or the information contained in this video is the sole responsibility of the user and not Motor Age magazine or its corporate parent, UBM Americas.

[@joshuapruden6497]

I said it once, and Illl say it again - This should be on cable. I would never leave the house. Fantastic channel!!!!

[@dtnel]

Mmm ya you would. To fix the car and then come back watch more after. Lol...

[@hydrocarbon7045]

Dude, have you been in coma since the 90s, mobil phones have internet now 😂

[@carlosv2474]

​@@dtnel yeah but you could put a tv in garage and you would still be watching it.

[@voltekhybridevrepair9901]

I've been helping some younger techs learn more about electrical troubleshooting, the first thing I told them was watch every single "The Trainer" video. Your videos get right to the point and teach very valuable techniques; thank you for your great videos and keep up the good work!

[@MotorAgeMagazine]

Thank you!

[@papapetad]

I had a kind of epiphany with this video. The negative side of a component in a circuit is the positive side of the next one down and that diagnosing of ground side issues with a "positive" test lead suddenly makes perfect sense. Between your videos and Scannerdanner's ones, I honestly get all the info I could hope for. I just have to get my hands on your books now because books are just the best along with practical experience to reinforce the theory. Thanks so much for taking the time to share all this.

[@MotorAgeMagazine]

Glad it helped you!

[@jimlee5626]

I am a pipeling cathodic protection tech. I am telling anyone I run into that is entering the NACE cathodic protection program, to head here prior to their week long classes. This is a super primer for preping for classes and testing. Thanks again for the clear professional presentation of concepts that are not easy to get ones head around. Well, done.

[@daraprak6498]

Just found these videos this past weekend, and all I got to say is, “WOW”!!! Love your incredible educational contents, I’ve been watching them nonstop since I found it. I’ve always felt intimidated whenever I had to work on anything with electrical gremlins; but now, I feel like your teachings have made me more confident 🙏 thank you

[@macegarage9603]

Same here 🔧

[@stevespeck3586]

Pete, this is the clarity of explanation I needed to help with my understanding of voltage drop on the ground side. Thanks for taking the time to make this.

[@arc3075]

I'm an industrial journeyman and work on HVAC equipment that can range from 100-1500tons. With the popularity of DC power playing a larger part in engineering. I FIND THESE VIDEOS TO BE AN ENORMOUS HELP TO ME. BIG THANKS TO YOU A D YOUR TEAM FOR PROVIDING THESE VIDEOS🍻🍻🍺🍺

[@ACommenterOnYouTube]

I had a 240V dryer line that would NOT run my dryer at all. Got an appliance tech out to check the dryer, he said we had a bad motor, spend $350 for a new motor and it still didn't work, he got a 2nd motor because he thought the replacement was bad, 2nd one also did not run ... WTF ... He got another tech to show up and they could not figure out why the dryer would not run. Eventually they said it was bad electronics in the dryer ... Purchased a new dryer ... Got it installed and it did not work. HUH WTF ... We called the company and they sent out their tech, he could not figure out why it did not work, then he placed an order for ANOTHER DRYER. Week later the 2nd NEW IN BOX dryer shows up, plugged it in and NOTHING ... NOW we are pissed. I checked for power at the outlet and got 240V but the dryer still didn't work. We got our $$ back from the NEW IN BOX dryer and took our "bad" dryer to a used appliance store that does repair. He plugs it up and the SOB works ... Took it back home and NOTHING .... So at this point is was electrical because it did work at their shop but not ours. I checked the outlet and got 120V on one leg and 120V on the other leg and 240V between both legs. Then i said, if we got 120V on each leg and 120V on the other and 240V across the two, WHY THE F is this not working .... Then the light in my head came on .... Voltage was only half the story. Voltage is just pressure but AMPERAGE is the flow ... Just because i got 240V between the 2 does not mean current will flow if there if a restriction. So i went and purchased 150 ft of 240V wire, went to the panel and disconnected the 2 hots from the breakers and wired in my temporary 240V line, ran it across the floor and to the dryer room, wired up the temp cord to the outlet and I WILL BE DAMNED THE DRYER KICKED ON AND WORKED ... After disconnecting the original 240V line that ran to the outlet and measured the 2 hots and the N wire, i had a 500 ohm SHORT between the black and red wire and a 1200 ohm short between the red/black and the N wire ... This 240V line ran from the panel, down and under the trailer and was just laying on the dirt, actually was about 6 inches below the dirt, it was SOAKED and WET and it was NOT direct bury wire .... SO the wire even though was passing the 240V .. when we tried to push current thru, the wet wire was restricting the current flow and enough to not allow the dryer to run ... after we yanked it all out, the 4 copper conductors were soaked and the outer jacket was just barely holding on ... So the water was restricting the current flow. Same as this video, that resistive fault is slowing down the voltage.

[@Hyst3ricalCha0s]

I've been hunting electrical ghosts in my vehicle (fu, Cadillac) for 5 months. This channel has been the absolute best at explaining electrical everything. Thank you. I wish I found this channel months ago

[@charlieogilvie2554]

Thank you electric training is crucial In today's world

[@spyonthesoftparade]

These videos are absolutely incredible, thank you so much for sharing your knowledge with us all.

[@fvrrljr]

photovoltaic/solar thermal technician: i use to restore classic cars and my first task was to clean all my connections especially the negatives on block and chassis. wish i knew this back in the day. my Hat Off 👍 Edit: watched video in english then added spanish subtitles. i don't know mechanic and electrical spanish expressions. the subtitles did your video justice. in my 60's so i know my proper grammar in spanish but not tech talk

[@pctuterman1]

Pete you're a true trainer. You really know how to keep my attention. You explain so well. You teach from a beginner's point of view and that's what makes your lessons so clear. You're great at what you teach. I love watching you because each and every time I do, I learn something new. Your experience at teaching really shows in your style and your method. Keep up the good works Pete and you will always have people like me who wants to learn more about vehicle diagnosis and repairs watching you. Thanks for doing what you do for us to learn. Maybe you should title your channel "Motor Age; The See Clearly Method"

[@MotorAgeMagazine]

Thank you!

[@Sparky-ww5re]

I don't do much work on automotive electrical systems, I work on residential and some light commercial, but this video regarding voltage drop is spot on. one way I've checked for voltage drop in a house, was I measured the hot to ground, hot to neutral, and finally neutral to ground voltage in a receptacle with a heavy load plugged in, such as a 1500 watt space heater. the neutral to ground voltage is the difference between the hot to neutral and hot to ground voltage. A receptacle with a neutral to ground voltage more than about 2 volts is a sign of high resistance connections somewhere upstream, or the wiring may be undersized for the load or length of the run. Sometimes it's necessary to step up to 12awg wiring on a 15 amp circuit, which normally uses 14awg, on longer runs from the panel, to keep voltage drop at the far end under control

[@darinstocks1184]

Pete I think you just hit my top 2 list. Almost ALL of that was brand new to me and with how you just explained it I feel as though I've known it for decades. THANK YOU VERY MUCH. I'm happy that I dropped in. :)

[@subietec]

Thanks Pete, you're a gentleman and a scholar

[@fredsalter1915]

Outstanding video, Pete! Very helpful and well explained. Thanks for making it.

[@skibumwannabe5492]

Been off the tools nearly 10 years, just needed to refresh. Good video, well explained

[@joshuapruden6497]

I just found this KZbin channel. This should be on cable. I would watch this all day!

[@MotorAgeMagazine]

Thanks! Call the Motor Trend channel and tell 'em to hire me!

[@mikecont9742]

Great information. Thanks for taking the time.

[@fredyflores3705]

Thank you sr for a excellent video. I'm attending school to an automotive technician and your videos help me a lot.

[@yellowtrain3161]

Great info! Very useful! I’m a locomotive electronics tech and these types of videos are useful as a reminder of different circuit testing techniques.

[@NewLevelAuto]

Beautiful presentation as always Pete. And perfect timing, I was just trying to explain this to a greenhorn I met on the road . I will show him this video ! See you at Vision

[@MotorAgeMagazine]

Awesome! Thanks for commenting.

[@smms1276]

👍 👍

[@DormantIdeasNIQ]

New Level Auto... you're a DONK...! and why you do not see how this presentation half sucks.

[@am.b5688]

People who didnt go to automotive/diesel school or are not real mechanics will never apreciate this guy the way we do, Just amazing!!

[@allenk5649]

This is the best instructional information to date that I have found concerning vtg drop, thank you!

[@MotorAgeMagazine]

Thanks! We truly appreciate that.

[@laurijorgenson6683]

Wow, do I feel grateful that I found your tutorials. I know very little about the topic but have always wanted to. I have an old motorhome that I know has ground issues but I need to find them. I love the way you explained this. Made so much sense to me and I felt like I got it. I need to begin putting this into action and testing it now. Thank you so much!

[@MotorAgeMagazine]

Glad you liked it!

[@m.b.smoshitoa8325]

Hi Pete, this info I saw it today, but does not grow old. Thanks thanks thanks Moshitoa (south Africa)

[@andrameda1]

Hello Pete, I have been regularly watching your videos, self educating and using your skills, here is a summary of your lessons: draw test in series with power pak; voltage drop, wire diagram reading, harness tracing, resistance ohms testing isolating wires between relays and fuses, and more, the splices on legs, I am learning and growing thanks to your group. This is what I have worked on to find the shorted wire, not yet found, the amp draw did not disappear yet. I could not find the harness #18 under the dash. There was a yellow connector with yellow wire under the air duck on center of fire wall in alignment with the shift dead center could not get to it. What I was able to do, was do parasitic draw test, disconnecting neg bat cable, setting up meter to 20 amps connecting meter neg lead to bat neg terminal ; positive lead to bat neg cable; got and amp draw of 0.11amps disconnecting all connectors one by one until the amp draw disappeared to identify the harness and the harness branches, the amp draw stayed on during the connectors, that were disconnected and reconnected; those to the left side of center console pillar; then to the connectors on the right side of console pillar, including the air condition connectors, all in center console. Proceeded to the connectors on the left kick panel; then proceeded to the connectors on passenger side heater blower and cruise control module, the amp draw did not disappear, at all. Proceeded to engine main harness, at the fire wall, with the rubber grommet protector, shaking it by hand, through to the fuse box, to the coils, to the injectors, to neutral safety switch, the brown ground wires by the coils and injectors, all the way to alternator harness and battery cables, the amp draw did not disappear from the volt meter? The engine grounds, where solid to body, not loose nor rusted. I was hoping to isolate the harness connector, by disconnecting it, exposing the male pins and the female receptor terminals making the amp draw of 0.11amps disappear; then using alligator clips to test each connector male pin on one side, then using a nail on the other end of alligator clip, gently touching the female terminals, one by one, until I found the wire, that would make amp draw reappear to identify that particular wire, within the harness, No response at all. I did not disconnect the fuse box to see the spliced wire tracing it back to gauge fuse and branch harness in upper dash. I did not want to remove the upper dash and could see, no connectors, to disconnect, further. I did not do a resistance test from EFI relay to the open/circuit relay to check a splice in wire diagram under fuse 10 (gauge) . I was not certain on how to proceed; thought about probing the isolated color wire identified by wire diagram, with a wire piercing probe but was baffled by how the colors of these wires changes on there way to ground, from one side to the other side, of the wire legs. Thought about a test light to puncture a hole in each wire with a good ground connection. Thought about the amp draw possibly on the power side of the circuit; afraid to connect test light to battery positive on a power side puncturing a hole creating another short power to power. Earlier on, during relay phase, I had tested the ground socket terminals on relays, both control and load side, by connecting test light to positive battery, the ground wire lit up, so they are good, all good, on every relay. The control/ load good too. All relays where tested for resistance on control and load sides and load side for current flow, excellent condition. This was a bully beat down, against what little skills, I've learned. You guys are tough and brave to contend with integrative circuits, I am evolving towards it, after so much pain. Respectfully, Bob Bishop

[@LAnonHubbard]

This clicked for me thanks! I now understand about how some resistance after the load (i.e. on the ground side) can create a voltage drop, thus "stealing" voltage from component earlier in the circuit. Been getting into car maintenance the last few months and electrics is a weak point which I'm having fun learning.

[@bobsmith3569]

Another great job explaining how to pinpoint the resistance, and reason for the load drop. !!!!

[@kylestenger15]

I’m a mechanic and still learn lots from your videos, thanks

[@orville58]

I've been watching you for some time now and most of my basic electrical has come from your "trainer" videos thanks for putting in the time to train newbys to the trade.

[@MotorAgeMagazine]

Glad you've found them helpful!

[@stevebanjo197]

Thanks Pete ! EXCELLENT VIDEO , I am starting to get it!!!

[@danielbrinkman8069]

very helpful thanks for making these tutorials..finally was able to get my mind around some of the stuff ive struggled with in the past

[@marcoescobar5302]

I appreciate the honesty and.. The dedication you take to pretty much Do about a years course in 15 minutes THE TRAINER. my respect. For the old-school wisdom... Learned something new today.....

[@MotorAgeMagazine]

Thank you!

[@skyliner32gtr65]

This is so true... especially STOP/START vehicles triggering STOP/START Malfunction on dash or STOP/START not working.

[@johnbennett2259]

Pete, that's a great explanation. I already understood voltage drop and now understand it a whole lot better, thanks.

[@MotorAgeMagazine]

Thanks for taking the time to comment!

[@nemanjadzombic6101]

Excelent explanation! Maybe the best explanation on the voltage drop on You tube so far. Very easy to comprehence.

[@MotorAgeMagazine]

Thank you! That means a lot..

[@jasonvergara7705]

Pete this one class clarified a lot of things for me after 35 years in the Field awesome like all your other Lessons

[@MotorAgeMagazine]

I'm really glad to hear that! Thank you!

[@davidm3210]

That was great boss - thanks a bunch and good health to you & yours!

[@stevenwilliams7254]

YOURE PERSPECTIVE HAS HELPED ME INCREASE MY CONFIDENCE AND UNDERSTANDING WITH WIRING CONCERNS. MY NIGHTMARES ARE MORE LIKE JUST BAD DREAMS NOW.....LOL THANK YOU SO MUCH!!! KEEP UP THE EXCELLENT WORK!!

[@MotorAgeMagazine]

Thanks Steven! Be sure to go to our channel's home page. We have an entire playlist on electrical troubleshooting there!

[@robealvarez2891]

People like you made a difference thank you

[@MotorAgeMagazine]

Thanks!

[@abderrahmanegouasmi7556]

Very very intelligent lecture. Thank you.

[@lawsonhollenbaugh3626]

WOW, PETE YOU HAVE REALLY OPENED MY MIND TO UNDERSTAND THIS CIRCUIT TESTING , GREAT INSTRUCTOR, MUCH APPRECIATED 👍

[@MotorAgeMagazine]

Glad it helped

[@richardmcwhirter9396]

Thanks again Pete, another great video with clear explanation, brilliant stuff!!

[@MotorAgeMagazine]

Thank you!

[@riccotexture8379]

Ty clear&concise very informative be blessed

[@joefeldoguiles8719]

I just started watching the Trainor.. Very interesting and informative.. Thank you.

[@jonnydcan9482]

Man you are great at passing this knowledge!!! Thank youuu

[@jimellerman5686]

This video still holds up well after 4 years!

[@apegues]

Great video Pete, I love watching these, I’m always learning something new and the rest is a great refresher

[@MotorAgeMagazine]

Great to hear!

[@michaelpigeon3591]

What great Channel Pete. I’ve stumbled across your channel and I’ve been watching it every time i get a chance. You are a great teacher. Thanks for what you do.😊

[@MotorAgeMagazine]

Thanks for saying so, Michael! I'm glad you find them helpful.

[@astritzyberaj6132]

Very nice and simple away to explain it,,even people with not much knowledge understand that..well done bud..thank and God bless..

[@wyattoneable]

Thanks Pete. You do a good job teaching.

[@MotorAgeMagazine]

Thank you!

[@4loyal]

Thanks Pete, great teaching!!!

[@selvamg635]

Well explained as usual. Please continue your educational video

[@123spuzzum]

Yipee! Finally it has been explained to me in a way I can understand. Thanks Pete!

[@MotorAgeMagazine]

Sorry for the late reply. 👍

[@richardmartini9784]

That was just perfect.... Man Am I learning.. You go Brother..great job..

[@randywl8925]

I never thought of actually checking the lead after the load like you did. I always thought you'd be checking resistance from after the load to various points leading to the main ground. In my S10, I cleaned the original grounds then added more grounds to the firewall and the front core support. Great explanations. 👍

[@tdb4297]

And all the hundreds of videos and dozens of friends I've had try to explain this to me it finally clicked with your explanation thank you so much troubleshooting a battery draining issue on my 1969 Ford f250 that I cannot figure out but this is definitely going to help I replaced the alternator the voltage regulator the battery wiring harness I'm just trying to figure out if it's possibly the starter solenoid even though it's new I know the remanufactured ones are often crap so I'm going to use this information and knowledge you just taught me to go home and test it out thank you so much!

[@MotorAgeMagazine]

Check out our main channel page and look for the electrical testing play list. I have a few videos on parasitic draw testing that will help you make short work of your issue.

[@RealWorldGarage]

Excellent job explaining this sir.

[@rjmagoon560]

This was a great explanation! Thank you!!!!

[@wallebo]

Great explanation.

[@glennpond4689]

Love the explanations easy to follow and is absolutely quality information here. Going to be using this info on my 87 mustang that just doesnt seem right. Battery drain over night but even moreso while driving. Thanks, Glenn Pond

[@MotorAgeMagazine]

Glad it was helpful!

[@lalpreetsingh9550]

Very very helpful to diagnose every load circuit.thank you sir

[@darrenflounders2803]

as always excellent in how you explain things

[@GHOOGLEMALE]

Excellent tutorial

[@ptours99]

excellent information thanks

[@paulloomis6734]

As always great information. Keep it up.

[@bernardrooney5266]

Very Concise . Even I understood !!!!! Thank you

[@pantelis241]

Gold Bless Pit, great informations thank you very much.🙏

[@mike-yp1uk]

Thanks for the back to basics. Sometimes it's the little fundamental stuff that takes us down a rabbit hole. I admire your dedication to create better technicians. Today's cars are complex and we are all in this mess together. Lol

[@MotorAgeMagazine]

Thanks Mike!

[@johnlenoir1023]

Thank you so much for sharing your knowledge and teaching these videos are making it a lot easier for me to try to understand how some of these readings can be and I have seen other videos on using and oscilloscope which I have recently purchased and I'm trying to learn thank you

[@DependableAutoTruck]

great video thanks it is truly simple once you get it but before you do its tough i watch these as refreshers over and over

[@griffer695]

Great video sir! Detailed information 👌

[@MukeshSingh-xy7cz]

Excellent sir enjoyed every bit of your lecture.

[@someguyontheinternet-]

Great explanation

[@bryanmitchell5728]

Great video!!!!! Thank you.

[@dennisgarryowen8885]

Excellent video, thanks.

[@mohamedrahib7685]

Great explication thanks

[@balbutie]

very interesting, you are good teacher.

[@gregscheyd4131]

THANKS PETE ; NICE , VERY NICE AND HELPFUL !!!!

[@MotorAgeMagazine]

Glad it was helpful to you. Thanks for taking the time to comment.

[@johneric3886]

Excellent work you have terrific communication skills, have a super day!!

[@MotorAgeMagazine]

Thank you!

[@sollykhan2385]

awesome video's Pete, please keep them coming 🙂👍

[@johnzore]

thanks again for a great video. john

[@NCPDFSB]

great explanation pete. thermal imagery help tremendously too.

[@1atech]

Are you retired 5-0?

[@drewandrews2732]

Big help. Thanks 👍

[@smms1276]

Second Time Watching This, Well Done 👍 👍.. Thank You

[@MarzNet256]

Really excellent!

[@General_Mayhem]

Thank you that was very clear.

[@derekdaniel9128]

I'm a newbie here, much thanks for sharing the knowledge.

[@MotorAgeMagazine]

Welcome to the channel!

[@dpenman1313]

Well done. Thanks.

[@procharger94]

Excellent video and clear explanation.

[@MotorAgeMagazine]

Thank you!

[@b_electric954]

Excellent video! Only additions I'd include are 1) everyone has heard of voltage, but far fewer have heard the term 'electromotive force', so since it was mentioned, I'd include a 10-15 second brief to quickly identify EMF and Voltage as being one in the same, just to bring the terminology full circle there, and 2) roll that into the specific relationship Voltage has with Current/Amperage in that Voltage, when viewed under the EMF perspective, it is the Electro'Motive Force' that pushes or carries the current and is the quasi-catalyst to current, as without the presence of "E"MF (aka: voltage), current (aka as both: amperage and "I"ntensity) cannot exist. (quoted initials reference pie chart variables)

[@samr.m.7709]

Awesome video Pete

[@Sctronic209]

Good refresher.

[@hammerhead6537]

Thanks again for another excellent video.

[@MotorAgeMagazine]

Thanks! Glad you liked it.

[@James-fs4rn]

👍 another great explination. Thanks

[@mikechiodetti6737]

Thanks Pete. When I was at work (retired now) I used to get vehicles with intermittents and unknown electrical problems. Some of the others either didn't understand this testing or gave up. I would show them. Some got it. One vehicle was at a L.A. Dept of Water & Power yard that was near the ocean. Oh ya, it brought back memories of Massachusetts and rusty, crusty vehicles. Body grounds varied in voltage drops. I ran a continuous number 10 gauge wire from a ground point inside the cab on the driver's side to ground points I found under the hood, finally crossing over to the battery on the passenger side and it's body ground there. Had to repair that ground on the body panel then bolt the ground wires solidly to that panel. Eliminated all the intermittent and unknown problems. THAT was a "fun" job! As Ivan would say. "No parts replaced."

[@nickayivor8432]

Good Morning Pete Meier take care and have a great day 👍 Great tutorial thank you 👍 From Nick Ayivor from London England UK 🇬🇧

[@AltonRowell-gb1lb]

Interesting stuff, thanks

[@thetabascomex1]

Gracias muy informativo amigo 🙂🤗