How to test an alternator (Chrysler Dodge Jeep)

This is a computer controlled alternator. The PCM controls the ground side of the alternator rotor field circuit. I will be walking you through the steps involved in making sure the wiring is correct.
For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available at www.scannerdanner.com as an eBook or paper book.
Want even more diagnostic training? Whether you are a DIY trying to fix your own car, someone looking to become an auto technician, or a current auto technician that wants to get more into diagnostics, subscribe to ScannerDanner Premium www.scannerdanner.com/join-sc... There is a 14 day free trial.
On ScannerDanner Premium I will bring you right into my classroom at Rosedale Technical College. You will find page for page lectures taken right from my book as well as exclusive classroom type case studies. What is so special about these classroom case studies? I pull live problem vehicles directly into my classroom and we troubleshoot them in real time, using and applying the theory and testing procedures we learn during the classroom lectures. There is no better on-line training of how to troubleshoot automotive electrical and electronics systems anywhere!
Disclaimer:
Due to factors beyond the control of ScannerDanner LLC, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. ScannerDanner LLC assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. ScannerDanner LLC 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 ScannerDanner LLC, 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 ScannerDanner LLC.

[@LifeSavingDefense]

How are there any thumbs down. This is real world old style troubleshooting with child included Great work.

[@lakisbouz]

ahhhhhhh what a breath of fresh air on the youtubes... someone who ACTUALLY knows what he is doing.. thank you so much, an absolute pleasure to see your thought process in action.

[@scrappylady]

You are the most amazing dad! The way you treat and interact with your daughter, I wish I had for my daughter. I love your videos too btw, I’m learning so much. Thank you for showing your processes and explaining everything.

[@ScannerDanner]

Thank you, I am not but I try to be. There is nothing more important than our families.

[@nineridesshotgun]

that was cool you brought her along. Normally that whole experience would probably be boring for a kid but I love the way you interact and keep them occupied

[@MediumHalf]

I love "in-the-field" troubleshooting like this, very educational and shows the twists and turns you end up with in real life.

[@nathanwright850]

Once again you're prove that understanding circuit design is worth it's weight in gold no fancy scan tools or even a wiring diagram,just a good head with some basic knowledge.

[@mike-yp1uk]

I can't believe how much fun watching or just listening to these videos are. There is so much useful info. It's all live training.

[@ScannerDanner]

Glad you like them! Thank you! Filming live has ALWAYS been the format on this channel and I am a teacher so I'm always teaching and talking my way through the issues

[@AllPraiseToYah]

Yet, again you came through Dan. I have that exact issue on my 2001 Jeep grand Cherokee limited. I first got the battery check at Advance Auto Part. The battery check out ok. I then had the alternator checked. Again, the alternator is good. Now after viewing to video, I'm going back to check the electrical connections and wires. I have to admit, this is not my cup of tea. However, I feel confident I can tackle the problem. Thanks for the experiences...😎🤜🏾🤛🏾

[@aodhmacraynall8932]

Fascinating! Love the aesthetic of hunting the issue down. I also appreciate you saying from time to time, "Why?" It makes us tinkerers feel we are not total newbz.

[@gixxercorona]

Mr danner, great video👍🏼 this is even better than a training lecture I've seen, and your doing it live, not staged, much appreciated from scotland (uk) please keep this up, as more cars are becoming more complex these days and more sophisticated , it's great to see Why your testing in depth and not just changing battery's , alternator for the sake of it, 👍🏼👍🏼

[@loseweightgetpaid5052]

After a bit of testing, I concluded that I have a short in one of the field wires since I did rebuild this engine it seems very plausible that I could've pinched a wire/wires. I've had a P1391 code since I put the engine back in. I've replaced both cam and crank sensors 2+ and retimed it 4 times since then because of this code. My alternator was bad through out this whole process and I was gonna wait to get another one til I got the truck running. Since I found your channel, I've learned how to better diagnose the electrical aspect side of things. I think the short will have a role to play in the code I'm getting. Going ahead and putting a new alt on may have helped me find out where my problem is. Thank you for your videos

[@keaaul808]

Awesome analysis, troubleshooting, and explanation!! Thanks for such an informative and enjoyable video, including your daughter!

[@alexmurdoch3828]

Thanks so much... been scratching my head on my intermittent alternator, this video was the cure! Was getting field voltage but it was a loose connection or bad brushes. works when I tap on the alternator. Thanks!!!

[@MikeJones-wf9mo]

Excellent video, I could not test the plug at the alternator because of the type of plug, no place to insert a wire/probe, but I followed the wires through the harness and found the harness was touching the exhaust pipe, It appears someone who owned the truck before did something and put the harness on the wrong side of the exhaust, thus burning the wires. All the other tests worked as expected, so I am sure when I rewire this, it will work. Thank you, best video I saw out of all the ones I looked at.Your daughter is awesome !

[@TheTexasCoder]

May, as a father of two kiddos about your age, your video was very very funny! Thank you for sharing it with us! Paul, thank you for the information, and sharing your family time! Rodents are never fun, I have seen entire harnesses changed out due to rodent damage...very frustrating! Great video, as always, keep them coming!

[@pitchforkpeasant6219]

Clogging up air intake entries with their nests too. On a few vehicles now

[@DjDubStak]

Good stuff. May is why u was able to figure this out lol. Love seeing a dad being a dad. Keep up the good work

[@shanebrandt7867]

I've been watching your videos for little while now I see how you incorporate your personal life is refreshing this video really touched my heart especially the part about Legos my son Joshua passed away 2 years ago that's all he ever wanted thank you for being a good man

[@ScannerDanner]

I am so sorry Shane. Jesus said "let the little children come to me". Your son is with our Creator my friend and you WILL see him again.

[@Geekdiymechanic]

Great video. Thanks for doing it. I have learned so much from you. I have solved numerous issues for friends using your techniques. Your little girl is great. I like that she is very polite. That is a reflection of you and your wife as parents. We already know you are a great technician. In regards to many of the previous comments, it is easy to be an armchair technician. It is many times easier to make an alternative call while not being in the actual situation. Lastly, you make so many videos for people to watch for free. Like you said time is money. So I really thank you for slowing down to tape these, add educational commentary, edit them, and post them.

[@ScannerDanner]

Thank you my friend

[@bartscave]

Well Danner, after I praised you for bringing your son on a job, I randomly watched this video. May is going to learn a lot as well! Good parenting.

[@gvvq-pi5ml]

This has to be one of my all time favorite videos on here, computer controlled alternator, how to test it...great stuff Paul from Fred in England.

[@icggeneric7836]

I can't live a day without you. Love you my friend.

[@FinalStopMobileAutoTech]

I have been repairing and diagnosing cars/trucks for over 15 years and since i have been following Mr danner i have been faster then i have EVER been at locating causes. I hate to sound like a broken record but i cannot ever thank you enough. regardless of opinions and comments witch might seam a little negative in response to your videos, I really pray you never doubt or second guess yourself, your methods or anything you display in any of your videos. Everything you have said and shown has lit a fire in me i cannot describe, and i can learn from home while i work during the day. KEEP IT UP BROTHER!!!!!

[@ScannerDannerPremium]

Just now read this comment. Thank you so much!

[@rbbbjl1]

May, i thought you were the greatest, i liked how you started to organize your dads tools. Organization is a key factor in our lifes, keep up the good work!

[@waiting4aliens]

Thank you. The importance of having a schematic on hand. Verifying a problem before pulling out the credit card.

[@wendydee3088]

Nailed it! Thank you for the step by step info. I'm going to check mine today after I install new battery.

[@trainer2018]

Nice job Paul, I would have attacked this problem the same way with a dvom, a test light or Load pro and some jumper wires. Then verify your results with your dvom, and if you understand circuit operation which is half the battle, like you do, this problem is found and fixed in a timely and efficient manner.

[@Paint0nBrush]

having a similar issue.. thanks for the help. didn't think about ground side switching.

[@jamesbaker7287]

Watched many of your videos and they are super informative and teach me alot. I think its awesome that you teach everyone this type of stuff.However, the best part of this video is the back and forth between you and your daughter. You're an awesome dad and shes gonna remember doing this type of stuff with your forever

[@ScannerDanner]

Thank you James

[@jamesbaker7287]

@@ScannerDanner no problem. Hey, I have a question for your, somewhat in the realm of this video. I installed a "4,000" watt amp, which is actually around 1175 rms and have 4 12 in subs in my dodge quad cab. I've been have issues with dimming lights. I've done the big 3 upgrade, and installed a high output alternator in but the lights still dim when the bass hits, even at low volume. The headlights are aftermarket halogen projectors(I'm currently, meaning right this second, upgrading the wiring harness from the stock connector to the bulbs with 10 gauge wire, hoping that'll help with less voltage drop. I've read that the issue could be my VR, which is in the PCM. So my question is, would bypassing the computer and installing an external VR help me out with this, or am I thinking of it wrong? Do you have any other suggestions I could do? I tried installing leds bulbs but my fog lights were brighter. I'm sorry if it comes off as more of a car audio question but it's really I guess about voltage drop. I know I have enough amperage from the alternator. Oh, the lights look like I'm flashing people and it doesnt just happen at idle, it happens all the time, including driving down the highway. Thanks for any help you can offer and sorry this turned into that. I just didnt know where else to ask and I seen your replied lol

[@ScannerDanner]

@@jamesbaker7287 are you using a big capacitor in your main feed wire? you should be!

[@jamesbaker7287]

@@ScannerDanner I can't find your reply about the capacitor but I was using a 2 farad one(was told 1 farad for every 1000 watts rms) right next to my amp but that didnt really work. Like I said, I'm hoping upgrading these wires and harness will improve it. Who knows, maybe my thinking is all messed up lol. I used 1/0 wire for my big 3 upgrade, I didnt put that in my original post

[@bigstuff52]

Man, between you a bunchesnd your brother,working on cars has gotten a lot easier-Thanks

[@95turbostang21]

Wow she is so young there these are the days to remember they grow up soooooo fast. Video's like this I know put a smile on your face Paul.

[@ScannerDanner]

Shes 13 now!

[@angeldelcourt6882]

You're a good man Paul. Love your videos and thank you for them.

[@joe00camaross]

Awesome video!! I’m working on my friend’s Jeep right now that’s having the same exact issue and you made my day!!

[@James-fs4rn]

I sure miss those days! They grow up way too fast! Thanks for another great lesson. There's a good alternator somewhere that came off it.

[@davidsawyer1599]

Hey Paul The YT algorithm suggested this video. I had viewed it back then. Just recently you had Miss May filling in for Caleb. It was nice to see. Stay well brother.

[@makingbakersfieldgreatagai9203]

GREAT VID .. I LOVE WHEN U R DOING FREE STYLE DIAGNOSTICS .. BCZ U LET US KNOW HOW U thought process is .. amazing Paul.. SALUDOS from Bakersfield

[@angelramirez3482]

Got to love these parts changers... Good thing is that they keep you busy... Keep up the good work,

[@EminHVAC]

Another excellent video, appreciate you sharing your knowledge.

[@karmanow666]

Really informative video you saved me several hundred dollars. Thank uou

[@tonyb8137]

I enjoy watching Scanner Danner videos and provides a great resource to learn from. If you guys want to learn this stuff though get his book and study it or take some classes to learn the basics first. You need to learn to crawl before you walk. This video is a prime example. My daughter has a Jeep of this same generation that she said didn’t charge sometimes and she would shut it off and start it up again and it would start charging. This uses the pcm to provide a duty cycle ground path to control the alternator output. That’s easy enough to see from the prints. What is not shown or might not be known is somewhere wrote to the pcm logic is that the pcm will shut down this circuit if it shows it is outside of a certain range. The pcm monitors this circuit from key on. You still get power, but no ground signal for the duty cycle signal. Back probing the ECM would have you think the EVR circuit is at fault, which is a common problem with these. Not wanting to leave anything to chance I measured the resistance on the field right at the alternator. I was reading over 350 ohms of resistance. Knowing something about electrical I knew this should only be closer to 5 ohms. While I don’t have exact specs I know this is pretty much just slip rings, brushes and wire to provide a field current. Rotating the alternator had this reading going really high to really low. Replaced the alternator based on that and everything is good. Moral of this store is get a good foundation of how things work. Also, just because something doesn’t show the results you expect it to. Verify everything else in the circuit is correct before you go replacing something like an ECM. Unfortunately we don’t know the logic the engineers have programmed into these things and the protections that are put into place to save a computer from destroying itself if something is out of range. Great videos though Paul. Keep up the great work.

[@ScannerDanner]

Thanks so much!

[@herbertlofton3588]

Scanner danner is the #1 dad....lol..love it

[@xaviergalarza5187]

You got the best help and I thought was the only one with my daughter fixing my car great job

[@velocity550]

Good catch on the rodent damage. I thought for sure as you did that the problem would have been in the tape wrapped area. Good call on the wrong field wiring. I have done initial testing to find results that don't match the scenario and take too long to second guess my results. Great little assistant too.

[@labradormcgraw2409]

There are only two people on KZbin with this kind of automotive knowledge, and the ability to port this across in a video. May is so sweet. I hope she got her Minecraft Lego set after all that assisting.

[@johnkenneth4443]

Dan only

[@RAFICKMOYO]

I'm really gaining the Auto Electrical repair Experience here, thanks bro

[@PURPLHEZ1]

We had a rodent do a number on a car once, ironically we knew the cause without much troubleshooting, because his getaway was shortened by a rolling GOODYEAR! Nicely, documented journey and quite good with the test method examples Danner! Today is change an alternator day for a Sebring 1999 , most likely. .5-2.8amps draw on Battery with all fuses pulled.

[@ScannerDanner]

Thanks Patrick!

[@sl5311]

Bet you are a great dad...great vid thx, I love how you keep in your mistakes...keeps it real

[@keatonaustin2280]

Probably just help solve my jeep issue. Not too sure at the moment. But gonna confirm in the morning! Thanks brother. Great vid.

[@edgardorodriguezflores]

I have the same issue with rats right now. Very helpful explanation, and going thru the real scenario. Super Professional. Super Mechanoc. Thank you.

[@ScannerDanner]

Awesome, thank you!

[@williamdebose8356]

Awesome video. Been struggling with a very similar issue on Dodge Best video so far Thank you!!

[@israelzunigamascorro9300]

excellent vidio, thank you for sharing your knowledge with us. God bless you and your family too

[@ozzstars_cars]

Terrific diagnoses Paul and May added good comic relief! Thanks for sharing

[@jhuntosgarage]

What a great Dad. Great job and a great job on the car too. ;)

[@rberth9016]

Thank you Dan! This video helped me verify a bad PCM with 00 Stratus. Same non charging issue, but ground wire to computer was not broken, verifying PCM. Thanks again!

[@ScannerDanner]

Awesome! Thank you. Oh, and my name is Paul :-) Danner is my last name.

[@entrecamioneros]

This video is very well explained! with sufficient information. thank you very much it was a great help!!!

[@nextlayersecurity]

wow. this vid is really great and nice to have successful troubleshooting "win" with explanation. thanks.

[@donniejohnson7499]

Another great video Paul thank you.

[@genemartin4540]

Details details details with adjustments for the discovery issues. I fixed my problem after watching the Chrysler alternator vs PCM.

[@Happy-Me.]

A quality video as usual. Thanks.

[@GuyCohenCoach]

PRO troubleshooter and a Great Father!

[@mikeochoa100]

You have the cutest baby ! Enjoy her every minute. They grow up fast!

[@rrmech11]

Thanks Paul Your daughter is adorable Tell your bro to put a vid Can't wait to see you do a pcm reflash

[@o4730]

Thanks. This was very helpful

[@Thilakprince]

* God bless you you two. . Thank you.

[@Inkd_watkins]

Great video Paul keep em' coming!!!

[@qnzboy223]

Video may be 3 years old but def learned a new approach with jumping straight ground the the alternator to see if it’s going to charge the battery. Thanks Dan

[@ScannerDanner]

thank you kelvin, keep in mind, not all alternators are controlled this way, you definitely want to do you homework before ever jumping a wire straight to ground. I'm sure you already know that, just making sure. Oh, and my name is Paul :-) Danner is my last name, but it's okay, I get "Dan" all the time

[@wtbm123]

Those mice can be a pain . they care not where they chew. I for one like your videos , and your way of teaching . It makes one understand the whole system and not just a quick patch.

[@Texasknowhow]

Your daughter reminds me of mine so much. She's a cutie for sure. My Abby is 20 now! Goes fast. Thanks for the video, I've got something similar going on with a 01 Lexus ES300 now. I'm going to check the same wires. There are three on the little connector of the alternator tho... One goes to the ECM; assuming that is the control wire. Keep it up man, you are a good teacher. Take care, Clay

[@rvscootin3457]

Great troubleshooting! Man did you get lucky spotting that break.

[@kmerkingdomfilms]

Paul, nice alt demo. May is very cute as well. I have a little girl about same age as May. Thanks for sharing Paul.

[@evanderoos9547]

Thanks buddy, exactly what the problem was 👍

[@Happy-Me.]

Sweet kid. Cherish as they are the future.

[@bradphillips6081]

Did such a good job I'm going to get you a tripod

[@MiamiBomber]

Can’t wait till my little one is old enough help me work on our cars and learn more than most guys do about them!

[@michaellovett2568]

You just gave me an in-depth look on a problem that I'm having with customer as we speak

[@DJDevon3]

Excellent video. Parts changer would throw a battery and alternator at it and that's exactly what happened. Great video.

[@johnmckamy6398]

such a good video , one of your better ones , sounds like your daughter likes to construct things maybe she'll grow up to be a automotive engineer .

[@hughvanzyl549]

Awesome MAY. Well done. South Africa

[@carlos92161]

It just a awesome video thanks for teaching us personally I really appreciate it

[@Waelkhalafabdelrehiem]

realy u are very good man between your life and your work i love the way you life

[@ScannerDanner]

Thank you my friend

[@SS-U23]

sweet kid Thank you for this awesome video. God bless

[@nevert1820]

Great video! It's like I'm watching the detective solve the case of The Missing Voltage! Dun dun dunnnnn!

[@movingupautodiagnostics8645]

You're so blessed! You have such a beautiful family! Watching this video helped me kinda solve or at least have a direction with an 06 Caravan that has the infamous lights-panel flickering problem. Testing the field control circuit I found that it is a power side controlled switch and it was flickering too (pcm power feed control). The ground was ok, it was constant, but when I went to check on the IPM connector that feeds B+ to the PCM it stopped doing it and I couldn't find the source. These intermittent problems are hard to solve... any clues?

[@bentech8887]

Very good video please keep them coming.

[@CinematicTouchProductions]

Thank you for your videos! Question my battery meter or gauge on my dash occasionally swings from just under 14 or over 14 but then settles at 14 but sometimes it stays under or over, today I put the multi meter on it with engine on and it read 15.3 new alternator?

[@EndofUSA]

Great KZbin course of alternator diagnosis!!! Pest (rat) intrusion!!! Let me make a conjecture. That vehicle was left sitting for months!!!

[@eduportillo]

Great, having the same problem, will use your help. What should I do, if those cables have continuity to the ECM and still not charging?

[@Romenite]

Great troubleshooting video

[@jessem8760]

Awesome video bud, keep up the good work. 👍

[@witnesszer0]

ScannerDanner +10 perception nice job love your channel

[@Z14kt12timandjes1]

Awe! You have such a great looking family!

[@salvatormartorelli2605]

Great videos! FYI Mice love wire coatings because one of the ingredients in their make up is peanut oil

[@vanlife4256]

May is patient because she wants her Lego!

[@R.E.HILL_]

I can hear Eric O saying that must be a Doorman generator... ☺ Nice one, thx for sharing.

[@boybravo689]

Thumbs up done what a good trouble shooting technique

[@seniorjuanvaldez]

what a great father! kudos

[@user-uj1xg7hb2u]

Fantastic and informative Video, Gain hands on experience

[@michaeldoc430]

Hi Paul Very NICE How do you luck out? I never seem to find the bad wire till I have a hr or so into it…. May.. Nice to see that you go with Dad, My daughters use to come out to my shop and help out, my youngest is 24 Janna, she thanked me for teaching her as a shop tried to rip her off by telling her that some part was bad when she knew better…. So keep helping your Dad and keep him in line…… Michael N2MX

[@salazam]

Ah so voltage coming from the green wire from the alternator gets the circuit completed by the computer when it needs to tell the alternator to charge (ground side control). By giving it ground directly you full field the alternator. And that's only on alternators controlled by the PCM. Then you have alternators with external voltage regulators like old Fords, which you jump the A and F terminals to full field it. GM's I'm still doing my homework. I'm trying to learn now to full field them all. I loved the video. I was on the edge of my seat! Electrical problems used to intimidate me but now they're exciting like solving a mystery! I remember the time I traced an open in the taillights in a 72 El Camino to the harness under the seat, took the seat out and saw burnt wires I wanted to hi-five myself!

[@ScannerDanner]

Great recap, that is exactly right my friend. And I agree, this type if stuff is fun! Detective work and problem solving is an amazing thing, especially when you fix it! Thanks for the comment

[@salazam]

@@ScannerDanner Dude, I used to be intimidated by this stuff and I would have never thought I'd be so enthralled by the mystery of chasing down faults. Once you understand the basics it gets so much easier! Thank you again for this awesome vid.

[@ScannerDanner]

@@salazam it certainly does! Thanks so much

[@jessgutierrez2552]

Beside being a Badass car electrician, your a Good Dad ,kool video😉

[@micksquirrel7248]

excellent video mate really pushed home DONT TAKE THIINGS FOR GRANTED . TEST AND PROVE well done

[@grassroot011]

Had squirrel damage on the wires in my Trooper, ate up over twenty some wires. Amounted to over $1400 worth of damage. After trying many repellents and such, finally got results using an ultrasonic repeller that is powered by the car's battery. After almost two years no more problems. But had three occurrences of damage before getting this unit. It was squirrels as they had a nest in there and were seen coming in and out of the vehicle.

[@johnbonifas6040]

Hi Paul I can’t believe he said your to deep into your scanner I use mine all the time I use my lab scope al the time that is how I find a drop out I use the verus edge

[@RyanBlace]

I would have enjoyed seeing an ac voltage test at the alternator's terminals after you jumped the damaged wire. I'm wondering about overheated (and failed) diodes.