How does an ALTERNATOR work ? How to TEST each COMPONENT with a multimeter and how to REPAIR it ?

The battery light stays on on my car.
The alternator is in rotation but the battery doesn't charge.
After checking that the issue doesn't come from the car, I test the alternator on the table.
I test it with a drill and observe that it doesn't work.
Before to open the alternator, I explain briefly the role of the
stator and the rotor.
I show you the schematics of the components of the alternator :
The stator, the rotor, the regulator and the diode bridge.
I test the rotor with a multimeter
I test the regulator, this doesn't work.
I test the stator and the diode bridge together and separatly.
I notice that a diode is in shortr circuit on the diode bridge.
I replace the diode bridge by a new and I refit it on the alternator.
Then I refit the alternator in the car.
0:00 Introduction
1:06 Test of the alternator in the car
5:41 Test of the alternator on the table
6:27 Alternator operation
9:02 Presentation of each component of the alternator
9:47 Tests just on the rotor
11:08 Tests just on the regulator
13:44 Tests on the stator and the diode bridge
15:36 Diode bridge removal
16:31 Tests just on the stator
17:52 Inductance measures on the rotor and the stator
19:05 Tests just on the diode bridge
23:02 New diode bridge refitting
25:56 Alternator reassembly and reffiting in the car
If you like this video, you can add a comment, share it, add a thumb up or consider subcribe to the channel.
This video isn't sponsored.
This video has been created for practical, educational, and sharing purposes. It neither constitutes nor replaces a genuine specialized technical manual. EnjoyWheels provides no warranties of any kind and disclaims all liability for the information contained in the videos. Under no circumstances can the author be held accountable by viewers for any adverse effects resulting from the use of the information presented in the content. EnjoyWheels recommends wearing personal safety equipment when carrying out tasks similar to those shown in the videos on this channel. If you are uncertain about the potential dangers of an operation, its consequences, or your own ability to perform it, seek assistance from a professional.

[@frankflowz6082]

Am paying a lot of money for my engineering degree and am watching this for free 😂😅

[@CraigWhitmour-qq2eg]

Bloody hilarious

[@dausproduction3945]

Work smart dont work hard

[@keithking1985]

Your better off having that degree though.. and if it's in electric engineering its a good one to have.. 👍🇮🇪🙏

[@user-ib7yq6uh7r]

One of the best explained alternator repair videos ever ! It should be used in high schools. Thank you!

[@EnjoyWheels_En]

Thanks for the message

[@nalo1728]

this is the most detailed alternator repair ive watched. 27mins not wasted . you sir earned a subscriber

[@EnjoyWheels_En]

thanks

[@dporrasxtremeLS3]

I 2nd this comment! Subscribed!

[@pitchforkpeasant6219]

Have never seen a better description and demonstration at the same time. Ever. 👍👍👍

[@EnjoyWheels_En]

Thank you

[@Zac_LDN]

This is THE best car alternator/battery diagnostic video I’ve seen. 10/10!

[@EnjoyWheels_En]

Thanks for the message.

[@jockofthebushveld299]

Undoubtedly the Best diagnosis of non charging condition in a Vehicle,and Theoretical Explanation and repair and testing on a Alternator, I've seen well done.

[@EnjoyWheels_En]

Thank you

[@bobbymathiwathanan1832]

What can I say? The best best super alternator repair video on CZcams. Thank you so much sir

[@EnjoyWheels_En]

Thanks for the comment

[@kjo2807]

God bless you, my Lecturer .That's my field. Also, I didn't know how to test the regulator ... but now I am thank you so much more blessings and may continue securing your life.

[@av8089]

exelent explanation, in detail

[@EnjoyWheels_En]

Thanks for your message !

[@cliffcampbell8827]

The details he provided was very accurate and in depth showing physical examples of the parts involved and how to check those components (while matching them to a wiring diagram via highlights) and the replacement of one diode.

[@thefirstcalled]

Thank you very kindly for your demonstration. Finally, a guy who knows how to explain things in a straight forward and logical way. Bravo!!!

[@EnjoyWheels_En]

Thank you for the message.

[@jeffmccrea9347]

A good quick go, no go, first test:
1) Turn the key to on. DO NOT START THE ENGINE!
2) Take a screwdriver, plier or anything steel and touch it to the shaft in the middle of the alternator pully. If it sticks hard like to a strong magnet, the voltage regulator and the field coil wrapped around the shaft are probably good.
3) Go to the other tests shown here.
When you go to test the diodes with a multimeter, you MUST know the polarity of the test leads. Depending on the meter brand, the internal battery voltage supplying the probes are not necessarily the same as the probe color codes. Example: Radio Shack and Archer meters made in the 80's and 90's had the red probe outputting a negative voltage as tested with another volt meter.
A diode is a "semiconductor". This means when functioning properly, it will pass power in only one direction like a one way valve will only pass a liquid or gas in only one direction.
If your continuity or ohm meter has a negative going red probe and you connect it to the anode, (flat bottom end of the diode in the diagram), and the black probe to the cathode, (the pointed end), you will get an indication that the diode is open, (burned out), when it may be perfectly good.
When testing diodes in an alternator, they MUST FIRST be disconnected from the stator coils or you may read a shorted condition by inadvertently reading the continuity of a stator coil rather than the diode itself.
Whenever checking any semiconductor whether it be in an alternator, amplifier, radio or crystal set, first, set your meter on the X1 or lowest ohms setting then connect the positive going probe to the anode and the negative going probe to the cathode. It is normal to read a few ohms at this point as semiconductors are not a perfect wire. Now, reverse your probes and test again. There should be a 0.0 or infinity reading or, on meters with a needle instead of a digital readout, zero needle movement. If you get any reading at this point, the diode, (bridge in an alternator), needs to be replaced.
Another indicator of shorted diode(s) in an alternator is a lower than normal, but present, charging voltage at the battery with the engine running. Normal charging voltages vary by car brand. Ford is between 13.2 and 13.5 volts. General Motors, (GMC, Chevy, Buick. Oldsmobile, Cadillac, Pontiac and Saturn) is around 13.8 and Chrysler, (Chrysler, Dodge and Plymouth) is 14.2. Chrysler police vehicles can be from 14.5 to 14.8 because of extra equipment.
Older 12 volt vehicles with generators, at idle, readings can be below 12 volts and still be normal. Increase engine speed to 1,000 RPM and test at battery for 12.8 volt or above reading not to exceed 13.8 volts max.
Foreign brands, check with dealer service department for acceptable voltage range.
Two ways to test for shorted diode(s).:
1) Set your radio to a dead channel in the AM band.
2) Start the engine.
3) Rev the engine slightly. If you hear a soft hum that changes tone like a siren that changes pitch with engine speed. This can also be noise from the ignition system. If this hum is present, with the engine running, take your meter, set it to "AC" at or near a 12 volt setting and place the probes on the battery terminals. (This will NOT harm the meter.) There should be NO reading at all. If the meter reads any voltage of any kind, one or more diodes are shorted supplying AC voltage to the vehicle's electrical system. This leads to a lower than normal effective charging voltage, could damage the internal filter capacitor in the alternator, irritating noise in some car radios and, if the ECM, (engine control module), has poor filtering or is "well aged", this alternating current, (AC), can confuse it leading to less than optimal engine performance, higher pollutant output and / or lower gas mileage.

[@EnjoyWheels_En]

Thanks for the explanation

[@MrHBSoftware]

you just put the multimeter on diode test. it should read a voltage drop of around 0,5 to 0,6 on one direction and nothing when you reverse it.....the rectifier assembly should be disconnected from the stator prior to testing...also check shorts between stator and housing and visual inspect for bunrt varnish or burnt smell from stator

[@1crazypj]

That was a really good explanation for anyone learning electrical repairs on cars.
I'm surprised you actually mentioned the diode direction of 'flow', that's very rare outside of an automotive school environment.
Well done.

[@EnjoyWheels_En]

Thanks for your message. Regarding the "flow" word, it's an french to english translation issue

[@stocks4bt]

I am a beginner in coming to a knowledge of the truth about electrical theory and electronics. What does electrical diode direction of 'flow' mean and why is it so important? thanks

[@EnjoyWheels_En]

The flow means the current direction.

[@m.fuadfauzi3256]

Perfect work troubleshooting video. Complete step by step explanation and of course the theoretical. I will wait the next and more video from you. Thank you.

[@EnjoyWheels_En]

You're welcome

[@charlescamen5225]

your video format with the real life and then the graphic representation is excellent and helps understanding.
thank you.

[@EnjoyWheels_En]

Thanks for the comment

[@wenze001]

Awesome presentation. Outstanding work. Thank you for sharing this.

[@EnjoyWheels_En]

Thanks for your message

[@spelunkerd]

This was fun to watch. Your work flow is very different than pro mechanics, yet still very engaging. Pro mechanics would simply swap the alternator, and a few with extra time on their hands would do a voltage drop test of the B+ wire and a ripple test to look for diode bridge problems. The ripple test could be as simple as switching your multimeter to AC to detect big swings in voltage as the device spins. In this case I like the way you pulled the three components apart and tested each in turn. At one time those three components were sold separately, but today it is hard to find individual parts that are all compatible. In the end it comes down to how much time you want to spend testing and then searching for parts.

[@EnjoyWheels_En]

thanks for your message

[@pitchforkpeasant6219]

How is a ripple test done

[@chadmason8526]

You are the first to explain that the stator wires are in pairs. Even the shop manual wire diagrams don't show this but now it makes sense. I hate when they dumb down info because I know something is off and then understand that they don't want you to know that much. Just buy another and replace it!

[@johnmichaelquizon4015]

Thank you for a very detailed & well explained video. Switching between the actual part & the wiring diagram made it very easy to understand!

[@EnjoyWheels_En]

Thanks for the comment

[@jemmoh2529]

A very clear and elaborate video. I have learnt more about the alternator.

[@EnjoyWheels_En]

Thanks for this comment

[@arthurfricchione8119]

New subscriber and this was an excellent description of how an alternator works and how to test one. Thanks for sharing. Artie. 👍

[@apackwestbound5946]

Thank you for your valuable and very clear explanation of how an alternator works and how to test the various components of an alternator. I was impressed by your repair as well. Thank you again!
-Respectfully

[@EnjoyWheels_En]

Thank for the comment

[@CrisDosGiulio]

You're the best! Really appreciate the soldering tips, that's gold for multiple other situations.

[@EnjoyWheels_En]

Thanks for the message

[@marcusmohorco380]

Congrats mate to your first uploaded video. It received a place in my personal "video hall of fame". Loads of work must've gone into this perfect explanation and presentation of this subject. I'm certain the video will hit 100s of thousands of views (if not a million!) within the next 4 years...
All the best, and keep up the good work for the rest of us enthusiasts who want to learn how to diagnose these things! Thanks!

[@EnjoyWheels_En]

Thanks a lot for your message

[@anthonyheak3479]

Very detailed step by step explanation, learned a lot from the video. Thanks!

[@EnjoyWheels_En]

Thanks for the message

[@WeekendMuse]

One if the not the best video on car alternators and troubleshooting I’ve come across on CZcams. Post-processing must have been time consuming but the end result is fantastic. A good mix between the practical and theory made your video highly engaging to watch. Also learned a few tips about soldering! Well done.

[@EnjoyWheels_En]

Thanks for the message.

[@bladder1010]

Excellent video. Very informative and concise.

[@EnjoyWheels_En]

Thank you

[@Don-ym8cm]

You have taken the time to properly explain how the alternator works . Thanks so much. Being looking for along time.

[@EnjoyWheels_En]

Thank you

[@carl-gunnarhillefors7612]

ELEGANT EXPLANATION AND RECONFIGURATION!
EXCEPTIONALLY WELL DONE!

[@EnjoyWheels_En]

Thank you.

[@Nyck461]

Great video with all the details. Consider this video as a class about Alternators.

[@EnjoyWheels_En]

Thank you

[@nattan3226]

excellent. give this man an award. videos like this deserve a thumbs up

[@EnjoyWheels_En]

thank you

[@anthonyheak3479]

Great step by step explanations! Thank you

[@EnjoyWheels_En]

You're welcome.

[@haf-oq3vt]

Complete teaching . You got 1000 likes from me ❤❤❤❤❤...

[@EnjoyWheels_En]

Thanks for your comment.

[@jjmhilu]

Good, perfect, clear, audible narration of fluent and perfect lingua franca! ,👌

[@EnjoyWheels_En]

Thank you

[@owariboko7539]

This is the best tutorial I have ever had as an electrician 👏👏👏👏. Good job man.

[@EnjoyWheels_En]

Thank you

[@Soldado_18]

i just found this vid and love the way you explained it with diagram next to actual component. thank you sir

[@EnjoyWheels_En]

You're welcome

[@brianxavier8873]

I've been looking for such an indepth explanation for a long time. Thanks a lot

[@EnjoyWheels_En]

You're welcome

[@marioskyrou9997]

I understand everything you said !!!! Thank you very much for the explanation!!!!!!!!!! I feel I'm ready to check my alternator!!!!!

[@EnjoyWheels_En]

Thank you

[@DooDeeDew]

This was an enjoyable 27 minute video, and very educational, great job.

[@EnjoyWheels_En]

Thank you

[@oranghingel3980]

what a wonderful video ,very clear with each and every component explained in real and in the diagram. Thank you very much for your time and effort in putting this video.

[@EnjoyWheels_En]

Thank you.

[@Reloadown]

Great job !! First time seeing something so in detail ... repair for an alternator. 👍👍👍👍

[@EnjoyWheels_En]

Thank you.

[@n4xyy]

Great diagonosis. Most of us would just replace the alternator... as I have done on multiple ocasions on several BMWs, including the water cooled version on my 1999 540 sport wagon. Thanks for the break down of the repair!

[@EnjoyWheels_En]

thanks for the message

[@HS-vz6jd]

I enjoyed watching the video, the style of explanation and clarification of the smallest details, with explanatory marks in different colors on the. important points, and I also liked the sense of humor sometimes in the video, wonderful. Thank you for the clarification.

[@EnjoyWheels_En]

Thanks for the message

[@ahmedidris4616]

This is first time to across a lecture like this. Thank you for educating.

[@EnjoyWheels_En]

Thanks for the message

[@maryfowler9997]

We did the Volkswagen alternator is just like that. Good to see somebody else doing the same have a nice day may you be blessed by all the different things in life. You already work the magic lesson share what you learn and be humble

[@EnjoyWheels_En]

thanks

[@VitaliyHTC]

Very informative and clean explanation of everything for Alternator :)
Interesting that there is a lot of variants how car alternator can be built.
Stator windings can be connected as Star Y or Delta Δ, in the case it's just 3 windings output will of them will have 120 degrees phase shift and some ripple.
Some alternators use 2 winding groups shifted by 60 degrees between them and 12 diodes rectifier (2x 6 per group). By shifting 2 groups with 60 degrees ripple is much lower which is mean less ripple/noise produced by alternator when charging/providing current for other loads.
As for my Mazda CX-9 2022 I found Alternator circuit schematic from MESI Mazda Electronic Service Information, alternator stator have 2 winding groups connected in Delta Δ and shifted by 60 degrees.
I think for BMW there should be something similar like electronic service manual/documentation.
Thanks for the video and one more subscription from me :)

[@EnjoyWheels_En]

Thanks for the message and the explanations

[@atishshirodkar921]

ONE OF THE BEST EXPLANATION ON ALTERNATOR. AMAZING JOB KEEP IT ON GOING.

[@EnjoyWheels_En]

Thank you.

[@christophermarshall5765]

Nice fix. Your description of what happened is correct.

[@EnjoyWheels_En]

Thanks

[@thatcheapguy525]

incredible explanation and video. you reason every step in the diagnostics and repair in the easiest way possible to understand.

[@EnjoyWheels_En]

Thanks for the message

[@hellassailing]

Incredible good instruction video, good verbally explained. You are a perfect instructor.!!

[@EnjoyWheels_En]

Thank you

[@herbertstolz2591]

Wonderfully demonstrated. THANKS TO YOU

[@EnjoyWheels_En]

You're welcome

[@celanindzabandzaba4056]

This has been one of the best education videos of my life, the way you elaborated every step and detailed reasons justifying whys. Please keep up the good work, It really inspire people like me. I am a self learning auto electrician.

[@EnjoyWheels_En]

Thanks for the message

[@manjulaupuli2624]

Very nice video regarding alternator service, its parts,function and testing with the recommended values.good for everyone who like to automotive engineering and industrial engineering as well.

[@EnjoyWheels_En]

Thanks for this comment.

[@antonio94]

Thanks for the video! Excellent explanation!

[@EnjoyWheels_En]

Thanks for the compliment

[@speedydanny4624]

thank you for this very detailed explanation.
learning about alternator of how it works...i might be able to fix my own when needed in the future..
very useful to know
thanks

[@EnjoyWheels_En]

you're welcome

[@user-wx3px8rt1l]

you explain very well

[@EnjoyWheels_En]

Thank you

[@shashi045]

One of the few wonderfully illustrated videos 👍

[@EnjoyWheels_En]

Thank you.

[@dennisebora]

Well explained! Thank you for sharing sir!

[@EnjoyWheels_En]

Thanks for the message

[@shekoo1609]

Very very informative and scientifically explained. Thank you very much.

[@EnjoyWheels_En]

Thanks for your message

[@Tactiquesmarketingsd-portfolio]

very well done vidéo ! Explanations are clear and easy to understand. Thanks !

[@EnjoyWheels_En]

You're welcome

[@stevenyee8967]

Excellent video and very helpful instructions and diagram.

[@EnjoyWheels_En]

Thanks a lot

[@vinotec4136]

this video make me feel like i was in class u explain everthing in detail nice work

[@EnjoyWheels_En]

Thank you

[@diepieche]

Thank you for making me fully understand video 🎉about alternator.

[@EnjoyWheels_En]

You're welcome

[@craigburns6447]

brilliant video, very informative and helpful

[@EnjoyWheels_En]

Thank you

[@tahupotikihaddon2967]

Thankyou for your knowledge I had bought a new alternator replacement as old one stopped charging and fitted it witch worked later came across this video and repaired my old alternator now I have a spare.

[@EnjoyWheels_En]

Thanks for the message

[@memocola8634]

This is gem.

[@justuslimumba1677]

Wonderful explanation 👍

[@EnjoyWheels_En]

Thanks a lot

[@Disharmonikash]

You are a really really good teacher. Please make one about the starter as well!

[@EnjoyWheels_En]

I have no starter that doesn't work. Thanks for the message.

[@karthikm4045]

Excellent Explanation

[@EnjoyWheels_En]

Thank you

[@frostieone]

Good clear complete explanation! Well done very enjoyable to watch!

[@EnjoyWheels_En]

Thanks for the comment.

[@erangnimbethou1481]

The lesson was very good, explanation and teaching technique was excellent.

[@EnjoyWheels_En]

Thank you

[@pelbak8110]

Well explained..Now I have a fair idea of fixing my Alternator..Thanks alot mate

[@EnjoyWheels_En]

You're welcome

[@balloney2175]

My alternator was born in 1997 (I bought my Honda Civic that year) had no problem ever since. Many thanks for this awesome video.

[@EnjoyWheels_En]

thanks for the message

[@jermainehuell7745]

This is the only video I'll ever need to watch about alternators. Im keeping it forever. ❤️

[@EnjoyWheels_En]

Thank you.

[@mansourtabaie2573]

Excellent presentation and explanation. Well done

[@EnjoyWheels_En]

Thanks

[@jayharks7710]

Excellent tutorial! This is good for students learning automotive electrical!

[@EnjoyWheels_En]

thank you

[@KASAD0]

Best alt repair and explanation video ! 👍👍👍👍 easy to understand

[@EnjoyWheels_En]

Thanks

[@brianimpellizzeri325]

Best alternator video ever. Thank you very much.

[@EnjoyWheels_En]

Thank you for the comment.

[@cezartrasfiero6443]

Thank you Sir for sharing your knowledge.

[@EnjoyWheels_En]

You're welcome

[@michaelhawkins5949]

Absolutely great learning,,looking forward to more videos like this.

[@EnjoyWheels_En]

Thanks for the comment

[@shironpathirana]

Amazing presentation! clear voice clear sentence! Good Luck!

[@EnjoyWheels_En]

Thanks

[@tokughasumisumi4052]

Thank You ! Top clear Explain in total in simple digestive manner.

[@EnjoyWheels_En]

You're welcome

[@AdePutra-lf9sn]

I like it! Its informative n helpful. I wish a lot more videos like this produced to serve other components of car.

[@EnjoyWheels_En]

Thanks for your comment

[@lalindaseneviratne8093]

good job
every thing clear perfectly

[@EnjoyWheels_En]

Thanks for your message

[@parisiadrian]

The BEST explanation ever!

[@EnjoyWheels_En]

Thanks for the compliment

[@maxwang2537]

Video nicely made. Very useful and well explained. The process is very logical. Thanks!

[@EnjoyWheels_En]

Thanks for this message.

[@jlinkels]

Excellent explanation. Problem is, for most modern alternators a replacement diode bridge or regulator is not available. Or the old one cannot even be removed. Diodes being press-fit into some integral part of the housing, wires not soldered but spot welded. Modern alternators are designed to be replaced, not repaired, and hence there are no replacement parts. That is right, you have to trash a $500 alternator because a 50 cents diode fail.

[@EnjoyWheels_En]

You're right. Thanks for the message

[@sunnymaria4927]

Excellent explanation! explains so clear

[@EnjoyWheels_En]

Thanks

[@tommderr209]

Excellent and detailed explanation. I hope your repair lasts and provides many more 1000's of KM of faithful travel! :D

[@EnjoyWheels_En]

Thanks for your comment

[@mechaniclifefrommyanmar]

BEST EXPLAINED ABOUT ALTERNATOR HOW DOES IT WORK AND HOW TO FIX.❤

[@EnjoyWheels_En]

Thank you

[@andrewjerome6644]

This was well explained love this channel!! Please keep post more videos

[@EnjoyWheels_En]

Thanks, some video 'll be posted next

[@BinhNguyen-ex4zn]

Amazing work, graphics and explanation!

[@EnjoyWheels_En]

Thank you

[@greatgerald]

Even without a show of face, The explanation is detailed that laymen with a little bit of idea in electronics could understand. Your video is a valuable reference. keep it up and thank you...👋👋👍👍👍

[@EnjoyWheels_En]

Thanks for the message

[@khanmuhammad9889]

Brilliant video explanation thanks you.

[@EnjoyWheels_En]

You're welcome

[@sonukumar-ic8hc]

Excellent explained by you sir

[@EnjoyWheels_En]

Thanks for the comment

[@karunathilakaabeysekara8642]

Really good explanation

[@EnjoyWheels_En]

thank you

[@MonkeyPunchZPoker]

Earlier today I watch a video on the electronicsNmore channel and thought it was by far the best video on alternators I've ever seen. The algorithm recommended this video, and now this is by far the best video on alternators I've ever seen.

[@EnjoyWheels_En]

Thank you

[@bradchew7937]

That was really well done, and very informative , and I got a lot out of it

[@EnjoyWheels_En]

Thanks for the message.

[@AdWat-lo5qx]

Excellent videos and practical implications .....Brilliant

[@EnjoyWheels_En]

Thank you

[@user-fj7vk2rf2y]

Best Explanation.. Thank you!

[@EnjoyWheels_En]

You're welcome

[@HariKumar-om6ek]

Very good to learn therotically and practically 🙏👍

[@EnjoyWheels_En]

Thanks