How to Test an Alternator
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- čas přidán 13. 05. 2014
- Diagnosing Alternator Problems. Learn how to test an alternator with a Multimeter. Does your car not start, do you have dim headlights or interior lights, does the starter sound weak when start the engine, or does your car die sitting overnight? This video will show you a few ways to test your alternator to see if it is bad, is going bad or is good. A good alternator will show a charge at around 14.2-14.7v while the car is running and under an electrical load it wont drop below 13v.
Here is a great multimeter for under $20: amzn.to/3sy10xH
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Disclaimer:
Due to factors beyond the control of ChrisFix, I cannot guarantee against improper use or unauthorized modifications of this information. ChrisFix assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. Use this information at your own risk. ChrisFix recommends safe practices when working on vehicles and or with tools seen or implied in this video. Due to factors beyond the control of ChrisFix, no information contained in this video shall create any expressed 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 from the information contained in this video is the sole responsibility of the user and not ChrisFix. - Auta a dopravní prostředky
Hey Chris, I'm a retired auto mechanic, with 4 years experience at General Motors Assy Division, (Back from 1978--1981), then 15 years as ASE cert master at a Chevrolet Dealer, then 4 years at an automotive mechanical claims facility (Call center for under 800.00 repairs). I have to thank and congratulate you for the outstanding job you're doing. You are helping people and asking nothing in return but for people to subscribe to your channel. You are helping thousands of people from being fleeced by the people that take advantage of people that don't know anything about the automobile or the industry that's giving them a bad name due to greed and corruption. My guess is the thumbs down people are the ones losing money thanks to your CZcams help. I just want to thank you and salute your help to people that are tired of being screwed by the shops and mechanics that are more concerned with making money than keeping customers happy.
Jumpercable wireless sir you are so right...love you comment
I simply don't understand how you get any thumbs down on your videos. Unbelievable; the nature of man. Thanks Chris for your exceptional videos.
Frank Ramirez i need those 😭
If u have an ase and all this experience why are u hear
@@georgedavis2634 hear
Outstanding video. Shady mechanic told me I had a bad alternator. Ran these test and it was within the mentioned volt range. All that was needed was to clean connector to alternator. You saved me $350. THANK YOU!!!!
Glad the video was helpful!
@@chrisfix My car has parasitic current draw of .02 amps under 12.6 volt 45ah battery. What would be the voltage of the car after sitting straight unused for 48 hour????
@@tnamen1307 There are acceptable current draws in newer vehicles. New car manufacturers say that 30-50mA (can be upwards of 80mA for trucks with a lot of accessories)is acceptable. Anything higher than I'd worry about it. Clocks and computers to some degree stay on even when in sleep mode so you'll always have draw.
Realistically .5V and below is acceptable loss throughout a vehicles entire circuit. Anything more than 1/2 a volt and I'd then worry about finding where the voltage is going.
@@Apocolis64 the voltage drops to 12.40 from 12.60 in just 2 days. Is this ok??
You are my hero. Since I lost my husband I've had to figure out how to do a lot of things on my own. The information you provide is detailed and specific and clear and anytime I watch one of your videos I come away with confidence that I have learned what I need to know from you. I appreciate so much everything you post because even if it doesn't apply to me today at some point I'm sure I'll need the information and the information you provide is so good thank you so very much for everything you do.
Renee, your post made me tear up. I am sad to hear that you lost your husband. I commend and admire you for having the strength to help yourself. I sense that you are a kind lady. I am on my own too and it is tough when we have to do everything ourselves. It IS kind of fun though when someone at work will talk about a car issue and we can pipe it, "have you checked ______?" and share the wisdom we learned from Chris (only we don't cite him). Even the men at work look at me and ask, "how do you know that?!" I fib and say, "I know some mechanics. I watched. I learned. I fixed some cars." 😆
@@thenightporter !0
100% - This channel has saved me thousands.....
RIP, to your husbands ladies, but you have to move on and get married again......
@@solarsolari6705tf are you even talking about
I really enjoy your tips and this one saved me a ton! Our 6 year old Lexus had trouble starting so I took it to Lexus. They said I needed a new battery ($400) and a new alternator ($600). They charged me $120 to diagnose! I guess I should have just gone to an auto store! Looking at the battery I noticed it was the original and there was a label indicating an 84 month warranty. I asked the service advisor and then he told me that I was eligible for a 25% proration off a new battery so it would be “only” $300 but he highly recommend terminal cleaning and protection for an additional $25. I was pissed so I paid the $120 diagnostic fee and drove it home.
I went to Costco and bought a larger AGM battery (27F vs 24F) and it fits perfect. I then followed your steps and discovered that the alternator is fine.
I could kick myself for taking it to the dealer for diagnostics but I didn’t know how to check the alternator until later.
Thanks and keep up the great work!
Dealers and auto mechanics in general are liars and thieves.. Find an honest one, they are out their ,few and far between but you can find one... , then stick with them. The rest let them Rot,, this industry is about the worse their is..Having bought and sold and repaired dozens if not 100s of cars over my lifetime,,this is what I've found to be true...
Dealership techs will do anything to get those extra hours.
Finally, someone that do an instructional video that's to the point and no rambling about irrelevant matters unrelated to what the viewers are seeking. Chris you are the textbook example of how videos for DIY's should be done. Thank you much.
EXACTLY!!!
Agreed!
Agreed 100,000%!
I definitely agree.🎉🎉🎉❤
Man, Life would have been easier 50 years ago if we had the internet. Life is getting better in a lot of ways. Not all though. Thanks, and you deserve your subscription and view numbers.
Thanks! The goal it to help people!!!
@@hoobered1232 No denying everything takes longer that way
@@hoobered1232 Right on ! And you didnt h have to worry about misinformation or lies .
@David McKee Yes I have to admit I have learned more about more things since the web just because of the speed of acquiring info . I wish we had CZcams back when I was learning the guitar . I used to taperecord song off of the radio and slow them down by wedging something into the tapedeck and play them over and over 100s of times to learn a song or find a tablature in guitar mag . Now you can find a lesson on just that song maybe even by the original artist . Learn the song in 30 - 45 min
@David McKee oh wow.
You must be lazy,reading books is a bad thing for you?
Chris, you are a ROCKSTAR! Thank you for helping me fix pretty much every issue I have had with my vehicles. You’ve helped me save $1000’s of dollars doing it myself! Thanks man!
Your video came up in a Google search for “how to test alternator”. You concisely provided exactly the information I needed to answer my question. Without all the crap. Sincerely, thank you!
I'm glad the video was helpful!
Just saved me $150! Cleaned connection to alternator and now it is working like new!
Lol!
One of the best auto DIY videos I’ve watched. Easy to follow, explained well without over doing it. Extremely helpful- thanks.
Thanks a lot!
Yes....your videos are so well explained and factual. No issues with being the look at me guy while you're shooting. Very appreciated!
New years day my Alternator went out on my Civic I needed a refresher course on testing it. Thanks for making this video.
10th gen civic?
It's been a while since I've had to test an alternator so I needed a "refresher course". I'm glad to have found this simple, too the point video that told me everything I needed to know. It helped me figure out that my brothers car didn't need an alternator but just a new battery. We had several days of sub-zero temps last week and his battery gave up. Now, if I can only get him to reimburse me for the price of the new battery lol!
Chris, you're doing a great service for people far and wide! Thank you
I am glad the videos are helpful!!!
Chris, u said that the voltage should not drop below 13.0v with loads on, but then u go on and say it should not drop to 12.7v. So which one? thanks for all ur help, you're awesome.
Jamie Delour
Shouldn't drop at all. Long as you have anough alternator to created the DC voltage and current. Also proper wire size and terminations. If your system drops below idle no load voltage, you have an issue. The entire vehicle and audio slash lighting systems are being under fed/performance.
James Leonard 2012 Volkswagen Jetta s
This video was awesome! Did the negative voltage drop test on the alternator. Found I had 0.8Vs of drop between the alternator housing and the battery! Pulled alternator and cleaned/sanded brackets and bolts and boom! Alternator putting out 14.4V instead of 13.8.. under load it was below 12.75V before cleaning. After cleaning it held over 14V with everything turned on. Great tips! Thanks Chris!
Awesome! Thanks a lot Luke!
what does removing and then cleaning the brackets do? provide for a better ground?
Thanks for an elegant, good, informative, clear, uncluttered video. I didn't have to sift through bad comedy or bad music or other gimmicks but just got what I needed. Well done and thanks again.
Love your videos Chrisfix! I used this video to diagnose an alternator issue with my 2008 Civic. It's almost at 300000 kms and your detailed and thorough videos are a big part of helping it make it to that milestone!
I was always told to disconnect the positive cable from the battery and if the car shut off, it was the alternator. I just checked everything like you described, and it turns out that it is the alternator not producing enough current. I'm still going to use your tips, especially after I install the new one. Thanks for your tips on properly diagnosing an alternator, I'm sure you've saved a lot of people a small fortune.
Can’t thank you enough. You helped me determine that my alternator was, in fact, bad but more importantly when it came time for me to replace it I paid extra close attention to the wires and bolts only to find that my negative terminal on the battery was rusty, the chassis ground was loose, AND the chassis ground wire was frayed. As soon as I replaced the alternator and negative terminal wiring my car started right up and it sounds better than ever. Thank you so much.
1989 Jeep YJ owner here. Thanks Chris for this very well explained video and giving me clear instructions on how to check all this and the reasons and logic in strange readings. Brilliant video. Thanks for reaching me how to figure these gremlins out and what to clean and replace. 100/100
Thanks a lot!
Well explained, and I love it when you say, "I'm good." Then move right along... very informative and efficient. I test wires in the field for a living, and I learned a few tricks to apply to cars. Great job, and you have a subscriber. You know your stuff.
Thank you, young man. You really packed in a whole lot of information. Great job. A video cleaning the connections would be helpful. Not for me, but for those new DIY'S out there. A lot of money is wasted on buying alternators and batteries that are not needed. Happy New Year and have a blessed 2020.
Terrific video. To the point with no useless commentary. Thank you so much for the great detail in what to do. 👍🏻
My wife's car battery was going flat after a week and knowing it wasn't that old I suspected the alternator. I was ready to buy a new one and just tried to find out how to test it first. So glad I came across your channel as the problem was a bad earth between the alternator and it's bracket. A little cleaning and the voltage drop went from .16 to .05 The car is charging fine so $$$ saved thanks to you. Cheers mate.
Finally, someone who speak plain simple language and doesn't ramble on or try to sell something!! Thank you!!
Fantastic video! Well filmed, diagnosed, instructed, & explained! Easy learning video, thank you Chris.
As always, you do a very thorough job with explaining and disclaimers. I always go to your videos when I get stuck because I know you do the job correctly with proper facts and backed up information to support the tasks at hand. I recommend your channel to any and all.
Thank you Chris!
Man, great vid! Going to test my alternator today, had no idea what to do. Your video made it very easy to understand, and love that you went through the whole series of checks for bad ground. Thank you sir!
Chris keep up the great videos. You teach me more about auto maintenance than anyone else on CZcams.
This vid is excellent - I especially appreciated the voltage drop test reminder.
Clear, concise, well done!
I'm a subscriber 👍
Hi your video is really GREAT! The way you do this voltage drop tests make a lot of sense! I am a retired electric engineer, with more than 50 Years of experience and I never saw this very logic tests IN A CAR! Keep on going my friend!!!!
Excellent video quality, I really like that you don't ramble about nonsense, you presented a set of diagnostic steps that I could convert easily into notes. I haven't done this kind of work in 30 years. Economic circumstances brought me back to the car repair world for my own cars and this is going to save me a lot of heartache with modern expensive mechanics.
This is a great video showing how to test your own vehicle battery at home if you own a multimeter. The only part you may want to change is where you said that you can add bottled water to the serviceable batteries. I wouldn't recommend that. Use only distilled water for lead acid batteries. I am a former Service Manager for a tire & lube shop and a former Technician at a water bottling facility. Thank you for making it easier for the D.I.Y.'r!
👍👍
Thank you so much Chris, I have a problem with either my alternator or battery and tonight I'm going to find out which one it is using your excellent tutorial.
+shane Blandford-scherr, I cannot reply to your comment for some reason but I hope you see this. If it only shows 11v then it can be a bad alternator, connection, or voltage regulator. Did you do the voltage-drop test I showed at the end of this video? That will let you know if the connection is bad. I think you just need a new alternator. The car is old and 170k miles is a lot of miles.
Thank you, I will do the voltage drop test, and if it fails that I'm pretty sure I'll end up scrapping it, clutch is completely shot anyways thanks again, great videos btw will subscribe
hey Chris finally ran that wire have had it for a while now just procrastinating but still no dice there is no fluctuation in voltage when reving the engine .My un trained mind instantly thinks bad alternator could autozone have lied to me two times on separate occasions in different cities tuff one to believe what I did discover is that there is some resistance at the terminals from alternator to battery to fuse box but but it seemed like the outer surface there is continuity so if you have anything that comes to mind really would appreciate it
ChrisFix
ChrisFix Nice video
Hey Chris I’m having issues with my 04 Silverado my battery not charging message popped up and I check voltage and it will decline into 11.5 as I drive once I turn car on though battery goes back up to 12.4. I don’t know what my problem could be truck turns on every time
Thanks for the straight to the point, no nonsense instructions and information. It came in handy! 👍🏽✌🏽
Great Video and Thanks!!! As a side note... You could also disconnect each wire, and use the Ohm (resistance) function on the meter to check for excessive resistance. This would cause the same voltage drop issue if there was excessive resistance.
Thank you for all your helping vids man! I'm planning to fix an old audi a4 and am really struglling with the battery stuff. Your information and advice are a great helper, keep it up.
Thanks for the lesson bro ur a good visual teacher clear and speaker and decent camera guy. We need more youtuber with ur teaching abilities!
Much Love, Dakota Burlein
Finally someone with the full check list , easy to understand for even my grandma
Even with all my years of experience working on cars. chris your videos are the best on the internet to teach people. Great work keep it up thanks.
Thank you so much brother! The end of of your vid with the voltage drop test was what allowed me to find that I had a bad alternator from Rock Auto and nothing else!
Yesterday I replaced the alternator on my 1G DSM (a 1991 Mitsubishi Eclipse). This was a very big deal for me, because I don't know much about cars. Replacing an alternator was the most complicated auto repair task that I'd ever attempted, so I watched several CZcams videos to help me understand what I was getting into. This video was one of the best, so thank you for posting it. The new alternator seems to be working great so far. I plan to check on it during the next few days, using sources such as this video as my guide. Thanks again.
+William Dye Awesome! That is great you were able to change the alternator! It isnt too bad and now you are ready to do more stuff! Glad the video was helpful!
I know this is 3 years old. But I also have a 1g dsm, it's a 90 talon Tsi, but you're lucky that was your first car repair. Some alternators I've done, you need to remove the tire and get under the car because its towards the firewall. 1g dsm alternator is a piece of cake, I hope everything worked out and that old beast is still running. Cheers.
40 yrs as an industrial electrician, learn the best advice from you, thank you.
Just swapped out a battery that went dead for a new one and wasn’t sure how to know if my alternator was the issue to begin with. This helped a lot and straight to the point you’ve gained a new subscriber. Thanks.
Glad the video was helpful!
This is the perfect pace and amount of detail for me to learn. Its very satisfying when you find a tuber tuned to your learning pace and style. Thanks for your work Chris
Yes....great pace...explained in plain speak. Well done to you!
I agree
Yes! Very important that tutorials aren't rushed or bogged down with too much info. This, as you said, was perfect...
I just changed an alternator that was faulty. Thanks for your amazing video!!!
Buying a multimeter as you suggested and testing my battery and alternator following your videos has given me peace of mind knowing I don’t need to spent (waste) $$$ having to replace either. Thank you
Chris you are very skilled. Your ability to teach even a person with no real experience. Thanks bud.
This video can't be any clearer. Awesome and so glad he did not add any music in the background. Keep it up! I am going to create a spread sheet on the instruction, print it and have it handky to fill in my own results, to compare with.
Thanks a lot! Glad the video was helpful!
Thanks Chris! I watched a few of your videos and there outstanding so i finally subscribed. keep up the great work!
Very well done my friend. Used the same HF multimeter and indeed, well stated and your advice...spot on. Saved me a trip to AutoZone and right to the junkyard where I grabbed a $27 buck Delco Remy rebuilt and installed it in the '98 Chevy Truck...BAMM, 14.2 volts instead of multimeter being all over the place with the old one. No idea if it was the voltage regulator that was going, but since it's internal, makes no difference. One again, increased my knowledge of cars just a bit more. Thanks buddy!
Thank you. I am single and desire to learn and maintain my 07’ Ford Explorer. I appreciate you for taking the time to show the steps & thought process (how and why) you perform the checks and the performance expectations. Am liking and subscribing. You made this very easy to understand & do. THANK YOU!
Thank you. This is something that I needed my dad's car has a bad alternator and this is something that helps.
Chris,
Your videos have made me a better mechanic, I've learned a lot from the many videos you've made. Thank you very much!!!
Paul
There is the old school to check if alternator is bad or not,,, donbt need multimer or wahtever..KKE'
Thanks for this. Had a battery and alternator checker and it was showing a high status for the alternator, so I ran your more detailed test. Nothing was wrong and everything checked out fine. Thanks for putting this together.
Explained great like in all of your videos! I would also suggest checking the connection of the actual battery terminal to the clamp itself and the battery cable where it connects to the clamp. That's where probably 90+% of the problems lie. Be careful with probing the alternator output with the probe! Touching the alternator output and the alternator case ground or any other ground will make a big spark! It could also damage the alternator!
One of the best videos Ive seen, you’ve helped a lot of people including me, Top Man, Thank You.
Thank you so much! This video saved me so much time and money on my wife's car.
Best channel on CZcams. You've helped me so much fixing my own car and family members cars. Thank you so much. No more having to take my car to a crooked mechanic. Can't trust anyone these days.
This is real good. I've known how to isolate alternator vs battery problems for years, and correctly, but these are some fine details and useful methods.
Great video, hands down, explained very clearly. I just learned something new. A huge "THANK YOU" to you!
One of the best step by step how too's that I have found ... Thank you...
Wow. 9-year-old video, but still so relevant and very timely for me. Also saved me over $400 on a new alternator. I just had a bad battery. Thank you so much!
Thank you Chris. Helped to confirm that my battery was low on juice and that my wife driving the car at night with full blast heating on short trips and our cold weather had resulted in a discharged battery. Alternator working fine. And battery charged again by running on idle for 10-15 minutes in daylight.
A 6 year old tutorial definitely helped me today! Thanks a lot Chris!
years later and im still using this video for car problems. great video :)
You've saved me thousands of dollars and improved my confidence with every project. Thank you
used this video to diagnose a failed alternator in my wife's car and then replaced it. over the years you've saved me thousands. thanks chris
Can't say "Thank you" enough for your videos! I replaced my battery, but have 12v when the car, no accessories turned on. Will follow the alternator testing tomorrow.
I'm glad the videos are helpful!
Ok thank you for that info!!! I went ahead and put in a new alternator and now it's reading 14.6 volts on a machine they used at the Toyota dealership!!!! Thanks again✌✌
So glad to find your video. It was posted 9 years ago but is still one of the best videos about how to test an alternator I’ve come across, and I have watched a few. Well done! Thumbs up from a new subscriber to your channel.
Just did this test today on my 07 Jeep and image passed the test!! Thanks Chris! You are freaking awesome!!
I went for an oil change and was told I NEEED to replace the alternator within a few days!! I decided to take matters into my own hands!
So what was the problem u fixed
Thanks for the info! I appreciate you taking time to explain this.
Damn this is a perfect, straight to the point video. Love it👍🏻
The best video I've seen on fault isolation between battery and alternator. Clear, concise and demonstrated with perfection. Thank you!
Chris, you are great with your videos. You are Always spot on when it comes to a fix. Thanks
Thanks Chris ! Thanks to you i have repaired a lot in my car and friends car also even started to make some extra money :) Trying to get better via your videos and who knows maybe soon will start running my own car repair shop ! Thx dude and you deserve each follower ! Cheers !
That's what I love to hear! Thanks a lot!
Thanks man! my battery was discharging and I ran all of these tests, turns out to be a bad chassis ground. Cleaned it, and now it works again
How did you fknd out that it was a bad chassis ground?
@@BIG_DRU It was just the last thing I checked, it looked corroded so I sanded and cleaned it and then it worked again
@@Jaspervandeno how do you find your chassis ground b
@@juliorubalcava95 its mounted on the firewall
Great info. I watched it 3 times. I love learning car stuff on CZcams. Some many people to thank for helping throughout the years. You made a sub out of this guy! Thank you for the video. Cant wait to binge watch your older videos. Welp, here I go!
I noticed one day when starting my car up that it was suddenly very weak, and had developed an odd, high-pitched whirring noise. I thought it might have been because I forgot to turn off the air conditioner before shutting the car off, but then I also noticed the windows opened and closed much more slowly than they had before. Thanks to this video, I was able to diagnose the alternator as the issue, seeing the battery was no longer getting charged with a constant 12.6. Thank you for the video.
Chriss, you're ok for me. I give you two thumbs up for this. You reminded me what I forgot long ago how to check my 1991 Mustang. Keep up the good work.
wow, this video is exceptionally well made. That's a milli for making it
Thanks Chris. This was a refresher for me as it is many years since i had an alternator failure. Great video.
Hey Chris I found this video very helpful especially on an old 2013 that keeps cutting off ,thanks for sharing
Thank you for sharing this. This was a huge help. 👊🏼
Chris your the best. I love how you explain things clear and make it dummy proof!
Thanks for presenting in a clear, concise and straightforward method. It is very much appreciated. Thanks
The best explanation I've seen so far about to check an alternator. Thanks!
Best video on this subject I've seen all day in trying to diagnose my car's electrical troubles. Thanks for the solid content.
I'm glad you find the video helpful!
Another simple, very helpful tutorial. Thank-you, Chris.
Thanks for the great lesson on diagnosing your batteries voltage and troubleshooting the whole process! Very helpful
I'm a macanic and this Guy knows what he is taking about!! good onya
Question is as a mechanic do you take the time to really check or do you simply try to get the customer to purchase something they don’t need..........
Easily done!! good job! Thanks
I know this is a pretty old video, but WOW - great . So very well presented, and easy to follow.
One of the best tutorial videos I have watched, thank you.
Thank you CF for another excellent, helpful how-to tutorial. Great to see your experience, knowledge, and sincere efforts to teach are all on the rise. You are on your way to a successful career. All the best to you young man.
Querencias7 Thanks a lot! I appreciate it! Im doing my best!
Thanks Chris your doing a great job man appreciate your videos
Great Job - Know nothing about volts and amps but your teaching me quickly - thanks a bunch
This guys knows all the tricks for real, I really appreciate your videos bro
I want you to show the output voltage of the alternator, i.e measured across its B terminal and its ground. However what you have displayed here is sufficient to give rough but adequate measurement of alternator performance. Measuring at battery terminals are usually sufficient for that purpose, unless we want further details.
As for my car, when the engine is off, my battery voltage is about 13V; when the engine is on and no usage of other electric related parts, the battery voltage is about 14.5V. The battery is new, so that is expected. :)