Vehicle Is Not Charging: How Do We KNOW It Is The Alternator?

viewers welcome back to the south main auto channel got us a 2006 Hyundai Sonata it's got the big 3 3 in it and it's not a charging anymore or at least it appears that way it got towed in on a flatbed lady said she's driving down the road you're driving down the road things and funny stuff started to happen and radio quit working heater quit working and check engine light came on car sort of running kind of crappy losing power and well she co-signed the road and triple-a did the rest to me those are pretty common symptoms you hear customers explain with you know an all-nighter that's failed even though the battery light itself didn't come on until after the car stalled and then wonder he started korsky on you know the light side I did order an elevator I assume that's what we're gonna need however we're not just gonna wing you know and almost $200 old air on it until we check it out so we're gonna run through some of those tests real quick pretty basic sips system got the generator you've got the battery you got the big battery cable that hooks to it and then you only have two extra wires on this one just the field circuit which is ECM controlled ECM is gonna control how much output this all Nader puts out and then the light circuit which turns light on the dash so pretty simple now a couple viewers have commented that they wish I explained stuff a little bit more in depth so with that being said I did stay after work today it's quarter after 5:00 and this was the only time that I usually have to kind of explain things a little more in depth so I'm going to show you the testing that we're gonna carry out now some of you might not care about this some of you might only care about Scotty up here in the corner with the chainsaw yes that is the man himself the big SK so I'll show you the tests that we're gonna do first I'm gonna do some drawing and usually this turns out kind of kind of funky but we're gonna draw our battery that is not a negative symbol that is and then we have our wire going over to ground and then we'll draw the engine this is not an exact representation of the 3.3 liter because this one has a front-mounted fan so that's the engine here is the alternator okay everybody follow along and then we have the battery cable that hooks - it will droplet pulley on it and a belt look at that run a crankshaft even very detailed and then up here we have the brain box the ECM and then of course we have the charge indicator light which that's our symbol for that so we have our big battery cable going to the alternator - battery - plus and then we have from the ECM going to the all inator we have our field circuit so that's what's going to turn on or all Nigar so to speak let me get you a little closer here so you can enjoy the artwork and then we have the L circuit it doesn't go directly to the bulb in this car but that's a close enough representation we really don't care about in that circuit in this case so the tests we're going to make is we're going to start the car we're going to stick our meter at the battery to see if it's charging I think we found it or we'll find in this case that it does as long as there's no load on it so we're gonna first check voltage here at the battery and then we have to do our voltage drop test and this is where some people get confused so remember voltage drop testing is just checking the difference between this point and this point between any two given points and what we hope to achieve by that is to say is this cable any good because theoretically if we have corrosion here the alternator or corrosion of the battery terminal we could add voltage drop so for example our alternator could be putting out let's say 14 volts from the battery it's only 12 well why is that well that's like say corrosion bad cable anything like that and by doing a voltage drop test we want to eliminate that so we're going to take our volt meter which is this little guy right here that's our volt meter and we're going to hook one of the terminals or one of the cables not battery positive and then we're going to hook the other one on the back of the alternator now theoretically we should have you know in a perfect world it'd be zero volts but we're gonna say maybe you know a tenth of a volt something like that we're gonna want to see very low voltage and then we're going to do the same thing on the battery negative we're gonna hook our voltmeter from battery negative and then we're going to take the other lead and go over to the alternator case ground because if we have a bad ground at the elevator we're gonna have the same symptom and then all we're looking for is the difference between negative and negative which should be very low again you know maybe a tenth of a volt something like that if those two checks test out good then we take our we're gonna use our ru scope so here's our drawing of our u scope and then we're gonna go from battery negative and we're gonna check to make sure this field wire is working so we'll just probe right into this field wire and what we expect to see there is a duty cycle control so key on engine off I'm expecting it to be let's say 12 volts and then the ECM is going to pull that signal to ground to you know turn on the alternator so we're gonna see you know the square wave 0 to 12 volts the compressor every time and to go full field like you know the alternator is saying you know give it full beans we would expect that line to just be it and zero volts pulled all the way to ground and that's all we want to make sure is that vzm has controlled the alternator we don't have any voltage drop on the positive side we don't have any voltage drop on a negative side and if that's the case well Robert dad's brother well Bob's your uncle and we can make the call in the elevator it looks extravagant it's not these tests would take you five minutes at the most so now that you know what we're doing it's done so I'll try to show you the best that can I totally forget I'm not gonna be able to get the camera down here cuz I'm gonna have to give it the old the old classic reach around to get down there but we can see our battery is nearly fully charged twelve point six to twelve point six six is going to be fully charged that a guy flat out on one video I did cuz I was doing something with a battery at twelve point one eight volts losses mind in the comment box in either case we're at twelve point six five we're gonna start it up then voltage drop negative it's all inator case negative positive it's all major positive I'm going to check taken right now we're going to change our scale we're going to just go down to one volt so we can see it in a little better detail this meter is nothing special other than the fact it's overpriced you can do this when the regular $15 meter from Sears & Roebuck I guess if they're still in business so before I even start it we'll just go a battery positive battery positive the matter which lead to use so make sure you go on the threaded stud of the alternator and then up here technically we should be on the actual battery post we'll double-check that so right now we're positive positive and we're going to see the potential difference between these two points take it fired up everything's out of the way but at all so you can see hopefully you can see we've got about a quarter of the bowl the two-tenths of a bowl roughly a voltage drop so either let me just go to battery center folks here just make sure that's the same our voltage drop has changed yeah so now you can see we're about 20 millivolts perhaps it's not putting out as much as it was because we can see what actual charcoal it is yeah see we're only at 12-point 12.3 volts so it has done giving up the ghost eyes I'm gonna check the negative side how roaring elevator pings I get my plan to stay on all right take it all back okay we're on all day turkeys might drop back to more detailed view here and we're about you know 20 millivolts they're not a huge deal and it just popped up next so we know with the circuit loaded as best as it can be currently that our voltage drop is well within reason now that quarter volt a voltage drop we had in the very beginning somewhat concerning but it's not the reason we're not charging scoot right over here I'm gonna grab a little usko I've already plugged into that field wire so I didn't have to fiddle around with that you guys now that it was overly difficult to get to but I'll take a plug in here and this is where we should see or alternator being commanded on let me know that's going on here let's see when I move our position up cuz I've got high plant put to the wrong wire that's why hey there we go now we're now we're cookin when you look at the battery negative everything works better so we'll get this down where we can see it we'll put this up on a five volt per division scale and then we can change our time basis here get a little more time on the screen and we can see clearly that the ECM is commanding this on and commanding all the way to ground why it's not full fielding it right now I really don't know perhaps it doesn't have that ability they can only go to you know higher duty cycle let's see if we can pull that up on the screen oops no okay there we go so our duty cycle is displayed up here in this corner kind of bouncing around there what about sixty percent duty cycle it could be a default strategy ECM I'm not sure perhaps it could have started charging out its and just check that real quick to be sure but I could have used a two-channel scope on this but no it's not it's clearly not charging you know 12.25 however it is being commanded on so with that being said we know our old inators bad at this point batteries good voltage drop is as good as we can chuck it without you know high low gaan well I feel confident calling the old neighbor guest fella not surgeon slapping alternator eyes well we would except for the fact that I've seen in wait too many cases you know credit connection causing a no charge and like I mentioned these tests are very simple if the elevator is relatively accessible it doesn't take too long to make 100% circuit now one thing we could do because let's say you know I know and you know that this elevator is really not putting out that much current we could check just to see I mentioned that you have to check these circuits loaded with current flow otherwise the results are your audience what we could do is unhook the battery cable from the alternator and we could put our carbon pile test round and actually put a load on it you know can that wire carry you know the hundred amps that this hauled maker can put out that's another way to do it you can do that with starter circuits - I did a video on my Jeep where we did that it was a no crank situation well how do we know that cables good without being able to put a load on well the only way is is well substitute load we substitute loads with test lights and in this case it's a high amperage draw so we need to substitute something high amperage I use my Carbon pile tester hook it on there crank it up you know will it pull 60 amps if it does good okay got changed apart and through the miracle of modern television the new alternator is installed a little bit of a son of a mother to put one of those in there not gonna lie glad I didn't record the process I just wanted to get it done it is kind of late and I want to go home so we're gonna redo all the tests that we did we're gonna look at the ECM command do our voltage drop test course make sure it's charging put it under a load make sure it's turning under load I'm just gonna hook back up hopefully it all as well back to there it will pop down to our digital meter again nothing fancy just a voltmeter with big screens we can all see it all right here we go let's fire this little guy up [Music] [Applause] no loads fourteen point one eight Holtz [Music] Scopus it back up here [Music] we can see that the alternator is being commanded on and it's going to be commanded on a different charging rates so every time the let's say the line is high here let's say 12 volts that's when the alternator is turned off and then the ECM is duty cycling it on and those little little packets there well I guess not really packets but we'll change our time basis here and you'll be able to see that a little bit better but if we look at it kind of in the big picture you can see how the alternator is turning it on every time these every time the graph goes low that's when it's commanding the Oh later on so theoretically as we increase loads that should change we can do that real quick let me throw out rear defogger and win the wipers and all that all right so we've got a under full load right now high beams literally fire blower motor on high we're charged in just a smidge over 14 volts we're on to make sure that stays steady and doesn't start to drop down you know back to battery voltage and then we can see our command for the alternator has changed also all right look at that you can see we're gonna be it looks like we're going to be holding steady just about that 14 volt mark and then now we'll do our voltage drop test when it's called the positive the positive first now that we know it's under full load right there's a single pan up of the fan you can see we're about 300 millivolts and I know our connection is good it can clean get this in a little butter buta force here so about a little over a quarter of a volt I'm not very concerned with that that is because of the you know carrying capacity of the wire I'm gonna assume so I'm gonna hook that had just the old inator wire here so this is gonna eliminate any connections that we can see we're at you know two hundred eighty millivolts and I'm hooked directly onto the wire for the all Nader so that eliminates you know this connection and this connection and that is just the limited capability of the cable that's hooked to it so not concerned with that and now we'll just go from battery negative cables from battery negative to the alternator case ground I went out and get that that's a hell of a Turk ace that it's on the negative post and we're about 68 milliamps so that's perfect that's under full load also see now it is that 100 percent duty cycle our field wire is pulled straight to ground I'll zoom you in on that and I'll go kick some loads off let's see here enhance all right that's good things switch around so we can see everything that's going on all at once cooling fans are on voltage is starting to drop it is being commanded a full duty cycle I want to see where this is going to go so after several minutes we're kind of going down like 13 to 13 4 and this was full loads of spent ahow of the coin fan at cycling so I'm happy with that particularly at an idle you can see where it's still at full duty cycle hundred percent commanded time but might take a shot off some loads we should see some activity that's with everything turned to back off and you can see that came back to life course maturity volts is going to go up a little bit let's bump the idle up about 1,500 rpms full load headlights on rear window defogger blower motor on full blast alright I'm pretty happy with that all right folks I'm gonna leave it at that now I know this wasn't the how to change y'all need around here Hyundai Sonata however if you're doing it it's a little bit of a chore I took a shortcut i drained the AC which shaves you about an hour off the book time on one of these so you can unhook AC compressor you know and hook the suction line to it then pitch it out of there twice as easy regardless I'll end this video to be more on being positive in your testing even when a car comes in it's not charging and of course you know we always say well it needs an alternator but in this case you know you got you know a couple our job to change it you've got a almost $200 part to put on and if you just go wing that on there you're wrong you know who's gonna eat that in this case it would have been me so I take legit five minutes it takes actually say yes the alternator is no good it's receiving a command to turn on you don't voltage drop on a positive side is good voltage drop on a grown side it's good it's a bottom line there's no questions asked then I think if you don't do that you're kind of foolish and just guessing but that's just my opinion so even something as simple as you know a car that's not charging I still go through do a couple quick checks and that way I'm confident because even in the case let's say you put a reman one in like we did in this case we got a tree man one from Napper you put it in now that one doesn't work oh now what do you do if you know you're testing is good couple them up telling me all nighters junk they send you another one you know it's as simple as that but you got to have some proof you got to have some data and you got to stick with the facts you know facts say this then you know it is what it is other tests we could have gone we could have you know Lok test the battery and everything else but I just want to kind of keep it as basic as possible hopefully you guys can learn a little bit from it not all alternators work like this they're all very similar when you're testing yours make sure you know it's steering operates you know perhaps that's your word smart charge and all you got to do is you know unplug it a couple volts drop tests and you know there you go several several different types systems know your system know what to expect when you test it and then do it I'll leave it at that I'm gonna get going get going home eat some dinner go down click subscribe ring the bell and all that business and while you're down there ring that Bell the Scotty always says and just murmur yours I can do it you can do it thanks for watching you

Channel: South Main Auto Repair LLC

Views: 187,806

Rating: 4.9617968 out of 5

Keywords: how to test an alternator, how to replace an alternator, 2004 hyundai elantra: not charging under load - test and repair, duramax alternator not charging issue solved, wiring problems alternator, alternator wiring issues, mercury alternator wiring, mobilemechanicservices, signs of alternator problems, how to test your alternator, how to test car alternator, how to test alternator on car

Id: X7DlOJ2oXhU

Length: 22min 17sec (1337 seconds)

Published: Thu Dec 06 2018