Voltage Drop Essentials - TST & Motor Age

G Truglia (TST) and Peter Meier (Motor Age) cover all the essentials of using the meter, especially voltage drop testing. This training class has been made free thanks tot he efforts of Motor Age and TST (an automotive training not-for-profit).

[@DayClanTribe]

After many years of messing with electronics I've only recently discovered the absolute importance of voltage drop tests throughout a circuit and how useful it is in diagnosing various issues. Excellent topic! Next tool on the wishlist is a good power-probe!

[@TSTseminars]

It one of the toughest test to get...practice practice...Thanks for watching....If you want to learn more about electricity and testing there is an online Electric Class going on this Monday and Wednesday June 29 and July 1...the other 4 parts are up for viewing/purchase at www.attstraining.com. If you have not already subscribed to our tstseminars KZbin channel please do so. Interested in more training? Go to www.tstseminars.org and view full length videos for members on TechFlix for $9.99 unlimited viewing and www.attstraining.com for hands on training and webcast.

[@TSTseminars]

@enix2k6 I would agree but Pete was testing neg to pos of the battery and then neg of the battery post to the load so he can show the techs that you would have to subract the reading to get the voltage drop. The best way to do it is neg of the battery to the load neg or pos of the battery to pos of the load. Thanks for your comment and for viewing

[@TSTseminars]

As long as the voltage does not drop under 9.6 volts while you have your pos and neg of the meter connected to the battery post. Now if you are doing a Voltage Drop from the Pos battery terminal to the pos of the starter...you have a big problem...HIGH RESISTANCE...broken wires strands, corrosion or poor connection. Hope this helps...Thanks for watching

[@MrGarcon98]

i will say from experience and schools ,,,a lot of people wanna go to fast and get to the high pay job without taking proper training of what is needed to succeed ,,,,take the time to learn it right i recommend don't rush , specially with electrical .

[@NobodyAskedForThis]

Voltage drop is used 99.99% of the time to perform electrical diagnostics in my bay. I honestly cannot tell you the last time I used the ohm setting on my meter and my test light hasn't seen the light of day for years.

[@TSTseminars]

to good to hear...after all VD is the problem most of the time with something electrical not worging correctly. Thanks for watching

[@MrVhandi]

The voltage in a series circuit is dropped over each and every load in the circuit. A load is just something with resistance. The filament in a light bulb is a resistor that gets so hot that it lights up. That bulb is a load. The resistance in the wires and all is also considered a load. Electricity doesn't differentiate between wanted(motor, light bulb..) and unwanted resistance(corrosion, wiring..) When the circuit is closed(connected) voltage drops across ALL resistances. so

[@MrVhandi]

Nice video though. I've watched this a couple times now. I'm just finishing my first year, and leaning more towards electrical diagnosis and systems. Electrical diagnosis is easy, and if you know what you're doing, you'll be in demand in the automotive field.

[@nickayivor8432]

Thanks 👍 From Nick Ayivor from London England UK 🇬🇧

[@TSTseminars]

Thanks for providing a review of what we said in the video cast...this could be helpful.

[@NyNj911]

these guys are great!!

[@TSTseminars]

Thank you for your comment and for watching...If you have not already subscribed to our tstseminars KZbin channel please do so. Thanks

[@TSTseminars]

No problem...thanks for watching and comment it help all of us.

[@DayClanTribe]

Great tutorial! There is a quality set of back probe pins that are much thinner than T-pins, very thin to get in tight wire connector fittings. I have a hard time getting T-pins into a various locations which result in no contact giving false readings.

[@TSTseminars]

Thanks for the info....If you have not already subscribed to our tstseminars KZbin channel please do so. Interested in more training? Go to www.tstseminars.org and view full length videos for members on TechFlix for $9.99 unlimited viewing and www.attstraining.com for hands on training and webcast.

[@TSTseminars]

MrVhandi it is impossible to have a 0 voltage drop since there has to be some resistance in every circuit besides if you look a little further in the webcast you will notice that we had the wire disconnected and OPEN. Thanks for your comment hope this explanation helps

[@MrVhandi]

At 49:47, G says it's impossible to have 0 volts. He says that means you have an open circuit. I think that's incorrect. If you have 0, you know your line is connected, and you have 0 resistance in the line. They were testing a very small portion of the negative circuit. It is possible that that had a very good connection, and was not dropping any voltage. The left over mV in the circuit are normal resistances in the wires/switches/connectors/anything that's not a load.

[@MrVhandi]

I watched the whole webcast. I know you guys disconnected the ground wire at the fender. I think I got mixed up with Ohms and Volts. If you were to have put an ohmmeter on it, it would show OL, which means open, and 0 resistance would mean it's not open... so on.. my bad. I have watched the video a few times now. Learned a few things :)

[@briangsandoval]

this is a great video. keep up the good work guys. love watching your videos. Thank you

[@stevefiorito5379]

Thanks for the presentation! I think that your demo on voltage drop would have worked much better if displayed on a vertical display board. It was difficult to see the circuit on the horizontal table top.

[@gtruglia2720]

+Steve Fiorito Steve I agree but as long as we got the point across it help technicians...thank you for watching

[@gtruglia2720]

+Steve Fiorito Steve thanks for the comment ... your feed back is important to us...Thanks for watching

[@vin605]

Awesome demo guys

[@MrVhandi]

the 26.3mV at the negative side of the load shows that there is still resistance in the circuit after the load, and voltage is dropping at it. If you have 12.0263 V at the battery, and .0263V at the neg side there, that means you have 12 volts still dropping somewhere in the circuit. Hopefully that's mostly on your load. The positive side may have about the same voltage drop before the load. (this 12.0263 example would be a dead battery, needs to be charged:P )

[@anthonysova7117]

The name of the product you mentioned instead of dielectric grease can’t understand what you said cheers

[@boybravo689]

Sir may I know if non computer circuit is same voltage drop bet. Voltage side and ground side of a voltage drop of 200mV tnx Sir

[@fivefortyeye540i]

If the load used all the voltage .. On the simple light bulb light circuit. Then wher dose the 26. 3 millivoltage come in at on the negative side of the load?? How is that calculated?

[@Marek_k123]

Hi. very good video. I have some questions. 1) Why voltage drop on source of electricity (12V battery)? ( and sometimes doesnt drop) For example : doesnt drop when connected small reciver (small bulb) and drop when connected medium/ high current motors ? And how this calculated? For example when 120 A starter motor is working constantly voltage drop 1V to 11V. And why drop 0.5 V when connected only 8 A fuel pomp motor straight to battery terminals ? Many thanks for any answer. Marek

[@TSTseminars]

Marek always start with a voltage drop at the source ...example if you are looking for a PRESSURE (Voltage) drop…place your meter Red Voltage lead at the most positive...the battery positive post and then take you black lead and go to the connection or load you want to check the voltage drop at. You do the same on the negative side of the circuit since electricity is a 360 degree circle. If there is electrical resistance ---wire, connections, bulbs, motors, there will be voltage drop. The maximum voltage drop on an electrical circuit that is non computerized should not be more than 200 mV with the loads on for each side. On a computer circuit should not have more than a 100 mV drop on either side. If you have not already subscribed to our tstseminars KZbin channel please do so. Also for more information checkout our tstseminar.org website. Thanks for watching...hope this helped

[@Marek_k123]

Many thanks for help. I'm all ready subscribe your channel since 2014. Watched all. And I'm very like the old long one over 1 or 2 hour videos. One of the best my host and teacher is Rich Peterson. Many Thanks thanks for everyone. Marek from Poland/UK

[@TSTseminars]

that's great...thank you for watching...have a great day :)

[@fivefortyeye540i]

Dose that left over millivoltage half to do with the resitance of load??

[@Reallopasz]

when i try to start engine my voltage on batery terminals drops to smth like 10volts, is this smth to worry, and also sometimes it doesnt start(clicking sound) so if it clicks it means open circuit?

[@walnuts1973]

What Amp probe are you using?

[@megomiftah]

great need some live work

[@picoboo5048]

I've been doing voltage drop testing and am not sure about how to voltage drop test a blower motor resistor or if it's even worthwhile ....

[@TSTseminars]

Pico Boo you do the voltage drop test just as you would on an other circuit. Positive on the meter to the most positive in the circuit and the negative lead to the feed B+ side of the resistor. The same would be turn on the negative side. Not sure if this info helps or if it answers your question. Any resistor will add resistance to the circuit and will drop the voltage. Thanks for watching and your question...If you have not already subscribed to our tstseminars KZbin channel please do so. If you interested in more training go to www.tstseminars.org...thanks

[@jawojnicki]

Hey G - I can't find "vulcanizing tape" anywhere. Is there a chance it is sometimes called "self-amalgamating tape"? If those 2 are NOT the same thing, where could I find "vulcanizing tape"? thanks

[@TSTseminars]

HomeDepot or online 3M or online.Mfr #: 2234 Adhesion Strength: 160 oz./in. Series: 2234 Temperature Range: -22 Degrees to 220 Degrees F Max. Voltage: 400 Item: Mastic Tape Length: 6 ft. Material: Flame Retardant Rubber Tensile Strength: 2400 lb./in. Shape: Continuous Roll Thickness: 60 mil Color: Black Standards: UL Listed, UL 510, RoHS 2002/95/EC, ASTM D257, D149, D2000-Type CE, D4325, D1249, D570, D69 UV Resistance: Yes Performance Temp.: Up to 194 Degrees F Width: 2" Country of Origin (subject to change): United States

[@jawojnicki]

DAMN! That's some expensive tape! 27 bucks for 6 feet!? I'll stick with the nail polish or liquid electrical tape for now, thanks. Nonetheless, I greatly appreciate your quick and helpful answer. Thanks again TST.

[@TSTseminars]

did you check the price at HomeDepot?

[@mr.technician4144]

Sir good day, would you mind if you make a video on how the ecm knows the misfire on EXACT cylinder....thank you for your informative videos

[@TSTseminars]

Mr. X right now I don't have time to do that since I am getting ready for the TST Big Event on March 21st that is taking up all my spare time. But I can tell you that the computer know what cylinder is misfiring but the crankshaft sensor. If the vehicle is under 8501 lbs and OBD II certified along with the correct cam crank sync the correct cylinder will be displayed as misfiring. Hope this helps. If you have not already subscribed to our tstseminars KZbin channel please do so. Interested in more training? Go to www.tstseminars.org and www.attstraining.com.

[@mr.technician4144]

@@TSTseminars thank you so much sir for the reply.....I'm also a technician of GM dealership and I under go also GM training in Philippines....By the way I am a filipino.....I watch everynight before I go to sleep on youtube for your informative videos and helps me make better... thats question of mine I'm thinking how the ecm knows the exact cylinder bother me because if cam or crank all cylinders involved because only on reluctor or teeth from camshft or reluctor wheel of crank. Cut off the magnetic field to induce voltage that ecm interprets or injectors miss on one or two cylinders or miss on spark....etc....thank sir I will keep continue watching godbless....

[@TSTseminars]

@@mr.technician4144 good to hear that our videos are helpful. I apricate you watching and taking the time to email me. Thank you. For even more info go to www.tstseminars.org and check out TechFlex...full length video that you can view for $9.99 a month with a membership of $75.00 for the year. have a great day :)

[@Reallopasz]

thanks for fast answer :)

[@MrGarcon98]

one thing is knowing how to interpret what you read on your meter! by this i mean reading it correctly as to how many decimals before or after the dot. this confuses a lot of people ,,,i seen it in class including me at times .just saying

[@jawojnicki]

I think Pete snickers a bit when G says, "We need to know VD...." Did anyone else think "Venereal Disease"? Ha!

[@gtruglia2720]

+jawojnicki Really :)....thanks for watching

[@built2last31]

grounds grounds grounds!!!!

[@troysmith9453]

VD only you Jerry 😂

[@rpmtechnician]

Buy a microphone guys RHODE!