HAVING BEEN A MECHANIC FOR OVER 49 YEARS AND A.S.E CERTIFIED MASTER AUTOMOTIVE TECHNICIAN FOR OVER 35 YEARS, I FOUND THIS VIDEO TO BE VERY HELPFUL FOR THE AVERAGE DIY PERSON SAVE BIG MONEY ALTHOUGH IT HURTS MY SHOP BUSINESS, BUT I WOULD RATHER SEE PEOPLE GET WELL INFORMED INFORMATION,RATHER THAN SCREW SOMETHING UP AND BRING IT TO ME WITH MORE ISSUES THAN THEY STARTED WITH, I HATE FIXING SOMETHING THAT SOME FOOL TRIED TO FIX BUT DIDN'T KNOW WHAT END OF A SCREWDRIVER TO USE

I'm an old timer, I used to work on cars from the 60s-80's. My easy test for an alternator, is to remove a battery wire. If the car keeps running, the alternator is good. After the car starts, it is running on the alternator. I also check battery voltage, 14v minimum, when the car is running. When an alternator is bad, it's usually the brushes that burn up. Either replace them yourself or take it to a small motor shop to have it done, it will save big money over alternator replacement.

As an older guy ; NAPA....i see on the battery. Experience shows, sometimes, that NAPA = Need Another Part Again. ....Not always, though. Sometimes.....they ' get it right ''.....Good video...young man !

Thanks so much! Clear and very informative. Just what I was looking for but didn’t think I’d find.

This is the most clearly explained, concise, and thorough video I have found on You Tube. Now I'm going to test my alternator armed with the correct info. I appreciate the effort. Thank you

Absolutely fabulous steps to diagnosis and so very clear - bless your heart and all who help us as you do!

My sons (17) car just stopped running the other day while going to school. I have his battery charging right now. I’m just trying to do a process of elimination. As a divorced mom of 4 teenagers (19,18,17 and 15) I’ve learned to do many things on my own or at least narrow it down. So wish me luck that I find out the issue. 🤞😉

Thanks buddy for a great tutorial of checking the alternator and battery....Your time and effort is very much appreciated! It helped me tremendously!!!

You might want to mention cleaning the battery termlnls. This was an issue for me that i figured out on my own. But this was super helpful. Thank you. Saved me lots of money.thanx again.

Very useful and simple to follow. Many thanks

Explained well and kept it simple for the "mechanically challenged ".

Very well presented With some cars the alternator isn't easily accessible from top of engine bay I've used this trick with constant results when suspecting a faulty alternator Simplest way without a volt meter to test where the fault may lay is Take precautions as you are dealing with electrics 1) visual check of cables on battery and back of Alternator, give battery cables a slight tug and state of battery connections If loose wire then reconnect if dodgy battery terminals then clean them 2) visual check belt, use the finger test, should be slight give, but not to much To much play means belt could be slipping, if to tight it can destroy the alternator, adjust or replace as needed 3) with car running turn on head lights, rev the engine slightly lights will brighten a bit If the alternator is at faulty you won't see any different in light intensity 4) with engine running disconnect the + (normally red cable) engine should still run with battery disconnected No electric being produced by Alternator so cars electrical system fails due to no electric Simple test than anyone can do even at the road side with no tools but a small adjustable spanner needed to preform these tests Hope this may help if you break down on route, or even a testing at home before buying a test meter unfortunately some road side Mechanics will blind you with gobbledegook knowing you are stressed and just want the problem to go away These four simple testes will help even if you are not Mechanically minded and could save you hundreds, if not thousands of unnecessary work

Thank you very much for the clear explanation. Showing and explaining the way you did . 👍

I was taught this over 45 YEARS ago but it never gets old 🔧👍🔧

Beautiful video, youg man. Now that's good old-fashioned troubleshooting!!

I shorted my negative battery post to a relay when trying to reattach my negative battery cable. Some dumbass put a non shielded relay too close to the battery. (me!) a few days later my jeep died on me while driving and wouldn't take a charge. Your suggestion of a blown alternator fuse saved me many dollars and a lot of troubleshooting. Thanks!

Nice presentation. Spoken clearly and concisely. Even though I’m not the brightest bulb on the tree , it was rather easy for me to understand and comprehend. Thank you. I learned some stuff from you!

5 years later, I used your tutorial. Thank you!

Nice. I replaced my alternator this morning.I cleaned all connections first and the problem persisted (low charging). It's a 2006 Toyota Matrix 4WD with 208,000k miles.And as you said, always check ALL connections and fuses first.

Thanks for your time to make a great video, very easy and informative.

Simple and direct explanation. TNX

great video , very clear , concise and to the point, sum utube videos ramble on n on with nothing to clear and super annoyance. keep it coming , please , happy new year !!!

Also, to properly check the status of any alternator's ability to perform its desired function in any automotive electrical charging system, you again simply set the digital multimeter to the continuity test/ diode check setting (marked by the electronic symbol that denotes a diode on your multimeter using a black line disecting a black triangle from its widest end, emerging from the triangle's pointed end which is marked with a short straight line that runs inversely to the 1st long straight line as it emerges and continues past the triangle's pointed end). Remove the alternator's positive 12volt power supply conductor from its positive 10mm bonding stud. Place the negative black lead of the digital multimeter on the alternator's positive terminal while touching the red positive lead of the digital multimeter to the alternator's negatively grounded housing/chassis. You should see a reading of .5 indicating the voltage drop across the diodes of the bridge rectifier ".5 is the voltage drop necessary to turn the bridge rectifier's diode array on". Readings between .3 to .7 are considered the absolute minimum and maximum limits you should see with an alternator functioning inside of its allowable operating limits, however a reading of .3 actually indicates an extremely weak and failing bridge rectifier, where a reading of .7 generally indicates a bridge rectifier that is about to also fail. The reading of .5 is really the desired target measurement here. Now reverse the leads of your digital multimeter, now placing the red positive lead on the alternator's positive terminal and touching the black negative lead to the alternator's grounded metal housing/ chassis. The digital multimeter should read "O.L." (indicating "Over Limit), which means that the bridge rectifier is preventing the reverse flow of current from the battery to the alternator as desired preventing the meter from detecting any measurements or reading at all. Any reading other than "O.L" (Over Limit) here indicates a failed bridge rectifier, which in turn means a failed alternator.

Absolutely excellent detailed, informative, great pace, basic ground level fundamentals are critical. I just acquired a 1970 VW Beetle convertible. It’s having some issues with the alternator charging the battery. It is extremely helpful and greatly appreciated. Thank you for your time, dedication, effort, sharing your knowledge with others. I am sharing this with many many people. 👍🏻😉🇺🇸🙏🏻✝️🇺🇸🙏🏻✝️🇺🇸👍🏻😉.

Very excellent explanation and fantastic. Now i can check my marine generator.

Thanks Aaron, the Alternator Discharge Light came on, and I keep my Toyota truck well maintainenced and loved, but you're right of course, I forgot to look for an inline fuse, which I'll do before I test for a bad alternator, Thank You!!!

Top tip if you dont have a multimeter, start engine in dark garage, switch on all the lights and as much other stuff you can blower heated screen etc, with the engine at idle, blip the throttle and watch the headlights, if they get immediately brighter your alternator is okay.

Thanks man, I just used your techniques and found the problem, after checking the battery and the alternator, like you did. The wire connecting the starter to the fuse box was not making a good connection, so I replaced it and it cranks up good again. I had replaced a battery earlier, so I saved a lot. Thanks again. Leo

Super excellent world class video. Thank you so much

This is a real nice video for a weekend warrior like myself who knows less than I believe. Easy to hear and see. Thanks!

gr8 joB Aaron, concise & through, excellent delivery, much appreciated ✌️

Im a 62 year old weekend warrior that commends you for a very well made video! Keep up the good work! Sincerely Steve

Very informative

Daughter got stuck with no batt power on freeway. I suspected Battery or Alternator 95 Avalon. This video allows me to test both before going to shop. Thanks.

Great job explaining

Also check the belt tensioner pully and arm. A weak one will also mess up the alternator if the belt is not tight enough on the pully to the alternator

You’re the man. I just fixed my F350.

Very good video. Thanks!

Thanks man I learned a couple of things very good info

Nice,excellent and easy explanation. Thanks

This really helped me out today - THANK YOU!!!

Awesome video. Thank you for sharing

Thanks. I downloaded this video because of your comment below.

Complete and detailed--thanks!😀

Great vid man thanks for all the helpful info keep up the great content

Nice1..Aaron & thank u

Good video! I use both. Battery load tester and volt meter.

Thank you for your video. I used your advice and found that the positive wire to the alternator was not connected well at the battery.

Thanks Aaron. This helped me big time! Very good video

Thanks so much! You explained it very well..

Very nice presentation keep up the good work, I learn from you appreciate you

Thank you for the upload. I will try some of these out on my wife’s Honda crv. It has a starting problem and we are tired of it. Even the mechanics have more or less given up on it

Nice job! I ran into a case where testing voltage at the Alternator’s stud provide a good reading but was not at the nut of the stud. There were corrosions between the bolt and nut that caused a problem (symptom like an open wire).

Very great breakdown!

AWESOME Video, thank you so much!!!

Thank you so much, Aaron....very informative and helpful!! U da man!!👍👊👊👊

This is the best way to test an alternator. Same for the battery, with an addition of an old style battery load tester.

Used this today. Thank you

Great video. Very educational simple and to the point I can’t stand the videos with all the theatrics. Good job.

this is so useful! thank you so much.

Very well explained! Thank you..

Great video. Helped a lot.

Girl here, and your video 📹 is extremely informative 👏 👌 🎉I'm still trying to figure out what is going on w my van

To explain Voltage Drop, you need to go into some detail. Kirchhoff’s voltage rule for series circuits.

Thank you for this video, I have a 04 Jeep grand cherokee 4.0l that i just replace the alternator and the battery. It gave me a check gauge light on and the battery level was just above 9v. I am now charging the battery it's at 11.3v and I will be check all that you said. Thanks again.

Helpful video. Thanks.

Great video. Thank you. Now to test the alternator on my 1976 Series 3 Land Rover. Best wishes from New Zealand.

Thankyou excellent info

Thank you for this video. Its very helpful. God bless!!!

Thanks bro for the video, it helped my pop and I figuere that our alternator and batterie are working.

very well explained thank you

Thanks, very helpful .

Awesome video thank you for the tutorial 👍

Such great video , thanks

Thanks for the info buddy

Thank so much for your great details video

I'll tell you of an easier way of testing the alternator. With the engine running disconnect either battery terminal (negative or positive) if the engine stays running the alternator is good, if the engine stops the alternator is not putting out a charge. 🤷

Thank you for the video!

Thanks. It was very helpful.

Good info! Thanks.

You just save me 400 bucks! Thanks man 😘

Video was precise and informative. Appreciated that you made a video that was easy to understand!

I normally use a Volt/Ampere Meter tester to check the charging output of a vehicle ( with and without load ).

Very helpful, thank you

This has been very helpful

Thanks I didn't know about voltage drop on positive and negitive to alternator.

Man....This video is awesome! You do an EXCELLENT job explaining and showing what to do....My truck had the battery light come on and go off a couple times one day while driving, and the truck's voltage gauge in the instrument cluster which had been showing that the battery was being charged, and would increase voltage with higher RPMs as usual.... Suddenly the battery light flashes a couple times and the gauge dropped to where it sits with a fully charged battery and no longer moved when raising RPMs....I made it home and parked it and have been contemplating what to do next....I'm curious though whether an alternator would be seeming to work fine then just totally quit....When I check at the battery posts it doesn't show anything, just the battery charge level itself, where it usually would show 14 when the engine was running, it was showing a full battery and the alternator charging but after driving it and the battery light flashing where it had been showing the battery being charged now it just shows the battery's charge level but nothing else....I guess I'll check the charging situation you detailed here and see what I get....could there be a fuse that blew or something somewhere, I don't know, trying to narrow down the cause as with driving it just running off the battery I don't want to be left stranded somewhere....Thanks for the video, this gives me some more ideas to check out. It starts up and runs....But for how long it would drive...It probably wouldn't make it to an auto repair shop....Subscribed to your channel. Hoping I can find the cause of these symptoms and hopefully fix it without a trip to a mechanic (I am mechanically inclined to some degree and grew up watching auto repair shows on TV, even more often than I watched cartoons 🤣😂🤣 This was a weird problem though how it went from charging fine to battery light flashes on and off a couple times and voltage drop....The battery light hasn't stayed on or anything but but not getting a charge....Great video. Super helpful.

Thank you for your help. Love , Debra

Best video. Thanx.

Very good video! Thanks for sharing!

Thanks 👍

Super video, thanks.

great video ... I followed instructions to find voltage drop and seems I am getting read of 0.3mv when Touch + - + and - to wire post on alternator . not sure where to go from there now that it seems there is a small voltage drop in the wiring.

Ty fam helped more than u know

Great info thank you

Killer vid! Much appreciated!

Very good video easy to follow 👍

Great video, Thanks for making it.

Thank you!!!

It would be nice to know if the negative on the voltmeter stays on the battery when taking the alternator reading.