Weirdest Subaru in the WORLD? (Part 1 - BARELY Runs with Alternator Connected??)

[@ATSNorthernMI]

Thank you for teaching us. Because of you, I am launching a business doing advanced automotive diagnostics. I also repair and build PC's and at one time was an electrician. I wanted to expand my horizon and being in electronics and electrical my whole life, it seems like it just fits. I've been slowly acquiring all the diagnostic equipment I see on your channel to get me started. The equipment is very expensive but at the same time no one around here does the kind of stuff you do. I've seen people getting their car towed a hundred miles away to a dealer and fork out thousands of dollars in repairs when I could have went to their site to diagnose and potentially fix their problem. I also want to get into lockouts and all keys lost. I had several people over the last couple of years working at walmart come up to me frantic trying to find their car keys. This kind old lady had lost the keys to her newer Lincoln 3 times and had to have her car towed to a dealer costing her several hundred dollars to get new keys made, when I could have provided that service onsite. Because of you and other youtubers in your position, have given me a new lease on life. It's something I really want to do and being encouraged to start my business is something I needed. Thanks again for what you do showing people like me what its like to do advanced automotive diagnostics and repair.

[@Hybriddiag]

Good luck bro ...i am also in my 2nd year of this business because of ivan learning alot from this great guy

[@PineHollowAutoDiagnostics]

That's Fantastic! It's a very challenging and rewarding field 😊

[@mikechiodetti4482]

Good luck to you in your new business. The Automotive Electronic field can be challenging and rewarding! Plus you have great equipment to help you locate the problems. Ivan, by now you probably have located the problem, but did did voltage drops on both the ground side and positive side from the battery to the engine block and the Bat Pos to the fuse box and the coil packs show anything?

[@johnlarkin549]

Good on you for having a crack! I think your teacher will help if you get a vehicle you can’t diag the good old cool Russian 😂 13:24 13:26

[@vadim7590]

Maybe it's God telling her to give it up driving 😅

[@OzFrog48Z]

I worked at a Subaru shop (shame on me). The PCMs would fail in unusual ways sometimes. I would run the car with the battery maintainer set to 14.5 volts and keep the alternator unplugged. If it still acts up the pcm might be at fault. I would also check the battery ground to the body. A bad connection at that body bolt will cause all kinds of problems. One more thing to check are the two small braided ground wires from the valve covers to the body that are almost always rotted off.

[@redtopberries]

Use a set of jump leads and make a temporary ground to the engine. Rule out your bad ground.

[@anthonysova7117]

I agree will eliminate and rule out ground problems By the way best comment by far KISS Cheers

[@stephenjones9153]

@redtopberries It's past 3am here in Liverpool UK and I just replied with the almost same suggestion use the TopDon ground straight to Coils and +Positve direct to Alternator or use a Spare good battery with Jump leads to Engine Ground and Alternator Positve +. 😊👍👍👍. Learnt from many year's of taking nothing for granted. 😊

[@stephenjones9153]

​@anthonysova7117 Definitely KISS take nothing for granted 😊😉👍👍👍

[@russellhltn1396]

The scope suggests there's no ground problem, but I agree with your strategy as connecting the cable is faster than connecting the scope.

[@natersalad889]

I worked at a trans shop for 10 years and it was pretty common to see 1998-2006 range dodge caravans that would shift erratically and actually upshift through gears sitting at a traffic like stopped and speedo would rise up to like 30mph or so. It was caused by bad factory alternators putting out excessive AC voltage and the output speed sensor would start picking up this AC voltage and make an erratic signal. We would unplug the alternator connector and it would go away, so we would install a new alternator and good to go, but it was the FACTORY alternators that would do this.

[@nickolaswilliams935]

Fun fact, caravans (and other Dodges as well) have the voltage regulator in the PCM. Meaning if you have a charging issue sometimes you don't need an alternator, you need a PCM! Pretty dumb huh...

[@mandytuning]

Ecm have the voltage regulator, alternator have the rectifier diodes that is what cause ac voltage ripple when it fails .Duhhh

[@fredautos]

Info is key

[@ferrumignis]

@@nickolaswilliams935 Plenty of modern cars have the PCM set the alternator voltage.

[@nickolaswilliams935]

@ferrumignis I don't like the idea, PCM'S are not cheap. Thankfully you can buy an external regulator if the internal one goes bad, I've don't that before.

[@jamesspash5561]

My thought is poor ground/s some place. works ok at low current, but when the alternator starts trying to charge the battery the poor ground cannot handle the current. The slow cranking also hints at a poor ground or/or bad battery.

[@braydinjones582]

Exactly my thought process.

[@chrisquinlan3012]

Reliving Saturday afternoon matinee as a kid 60 years ago ! The passenger train is heading to broken bridge ,our hero Ivan is in the cab fighting valiantly against the bad guys and the cinema screen lights up TO BE CONTINUED..........ARRRGH !!!!

[@dans_Learning_Curve]

200K+ subscribers and I don't think you've asked for anyone to subscribe or even *"SMASH THE LIKE BUTTON"* !! You're definitely doing something right!!

[@timkis64]

i swear i like this channel more every week.he gets into some weird rare problems, but finds solutions to 98% of them.gotta respect such dilegence & determination.

[@bartscave]

I had a bad battery cause symptoms like yours. It made the alternator go to full output and would overload the poor little 4 cylinder. It was a huge tractor battery that the owner installed.

[@davidche554]

I've scoped those coils before there is power and ground and the third one is a pulsed close to 5v square wave that signals to the coil from the ecm to fire.

[@shuriKen469]

banger of a case study this one. cheers for sharing mate!

[@erickphd]

Wild guess - use your battery maintainer to raise the voltage to 14.2 or near that without the alternator connected. See if that duplicates the alternator connected symptom. Guessing at the age of the car there is an electrolytic capacitor breaking down in the engine computer (or elsewhere) when at full running voltage.

[@PineHollowAutoDiagnostics]

Great thought process! Yes we want to rule out the alternator completely 👌🙂

[@tomtke7351]

golly.... what a great channel... and a great mystery.... Just started watching and had to jump in...

[@TheRetarp]

Need to confirm and diagnose the parasitic first. If not related to the running rough issue I'd pull the accessory belt first. Then test belt on with disconnected alternator output wire. My guess is some sort of bad ground. Take a meter and measure from the alternator case to the negative battery post while running rough. That will tell you immediately if there is a floating ground.

[@titaniumman_22]

Perfect release timing before date night! Thanks Ivan! 🇺🇸

[@iosifsabinlaposi4846]

Hello, It looks like a ground problem. It should be 2 ground wires that connects heads with the engine block(under the car) and a ground wire that connect engine block with the battery and body of the car. Check that wires.

[@tonyedwards5782]

Try a jumper cable from alt housing to battery ground and see if the problem goes away. I suspect a missing ground.

[@maxnoe3079]

I would check the grounds you were mentioning. Subarus are notorious for weak grounds when they are all good. I guarantee the ground straps on the bottom of the engine are rotted off. So the ground to the starter is the only ground you have. I bought a 08 Impreza for $500 because they couldn’t get it to ever charge the battery. New battery n starter. Still no charge. I got it home and checked the grounds. Straps on bottom broke. Ground at starter loose. Fixed the grounds and everything works fine now. Oddly though it would start just fine so I guess the starter doesn’t need much ground to work. They do spin over pretty easy.

[@JoseSilveira-newhandleforYT]

Wow! Put crazy on it, Ivan! My first though was that the alternator was loading the engine excessively and whatever other problem the engine got, was increased. But the possibility of a bad ground being overloaded by the alternator seemed even more plausible. Maybe it's a mix of both. Can't wait for Part 2!

[@janpur1417]

That alternator wiring diagram is what I've wanted to check on a Toyota Hilux 1990 alternator. It produces 13.4V max, so bought all OEM rectifier, brush kit and the IC regulator. Before I install the IC regulator, I wanted to check the existing IC regulator by applying batter voltage to the battery wire and check the voltage at the brush kit (while it is not installed). I learned a lot from your channel and wanted to say THANK YOU IVAN!

[@watsisbuttndo829]

My 94 hilux used to go through alternators pretty regularly, i surmised it was because they were mounted low down on the engine (22R) and were picking up a lot of road spray. The only time that vehicle let me down in over 500,000kms was the alt siezed without warning one day and snapped the drive belt. Same belt that ran the water pump!.

[@jamesspash5561]

I had a Chevy Chevette. years back. Ran fine started, charged fine. However once in a while on a damp or rainy day it would not crank. In the end it turned out to be a poor starter ground. Aluminum starter housing on an aluminum bell housing. Sanded clean, issue solved. Grounds can be confusing. Some cars , as you know ground the battery to the chassis instead of the engine, then run a bonding jumper to the engine. The flexible braided ones look OK, but, are great for turning to dust her in salt land.

[@JOHNSUE28]

Ivan, Years ago I had a tip in hesistation output and rough run that I traced back to the Alternator diodes. Alternator rebuild/replacement fixed it. But I have to admit it wasn't this severe. Found it by checking for AC voltage output.

[@ivanhorban340]

I have had two alternators that had corrosion on the ground stud that mounted the alternator's voltage regulator. I pressed out the stud, cleaned out the corrosion, coated the parts and stud hole with aluminum wire contact paste. The problem of lights dimming and brightening went away. Maddening, as the problem was intermittent, road bumps, rain, hitting the brakes and just turning the wheel at times. But when I would check it, it produced the correct voltages.

[@derekmcfadyen127]

I had the same type of fault ... same car ..... new alternator fitted .... brought on engine management for air flow meter...... turns out only original manufacture alternator was the way to go ........crazy never seen it before lol

[@brianw8963]

Cool! Still suspect a short to ground somewhere on the main charging wire. Something is loading that alternator down pre fuse. Love this stuff! 👍👍🇺🇸

[@bobweiss8682]

Next thing I would try is disconnecting the main output wire from the alternator, connecting the battery maintainer (set to around 14 V to simulate alternator output) to the disconnected wire, and see how the engine runs with and without the alternator field connector plugged in. How much current is being pumped out from the alternator? I would also take a minute to look into the parasitic draw complaint--it may be related?

[@rhkips]

I'm racking my brain, but I can't even put together enough of a hodge-podge to speculate! Dang Ivan, making me wait for part 2! This is a spicy one~ :D

[@fredsalter1915]

One of those wires on the alternator connector is shorted to a coil or injector wire. Bypass the connector and manually run a length of wire directly to the battery's positive and another one to the battery's ground. Plus, that connector looks like it has three wires!

[@spelunkerd]

Ha ha, you left us hanging. Along the line of gaining info, I think I'd look to identify which coils are dropping out. If we can show it's the same coils each time, we could swap position of the coils and see if the abnormality follows the coils or stays with the driver. And while at it, I'd try to look at the ground wire for the specific coils that are abnormal. Perhaps they share a branch ground and the connection from there to the mother ground is tenuous, exposed with more power use. What a great case....

[@kevinshasteen5682]

Back in the "good ole days" when you could actually rebuild an alternator where voltage regulators were external of the alternator; crazy things happened when the bridge or voltage regulator failed. In those "good ole days" if an alternator failed, the battery and starter usually wasnt too far off from failing also - but you couldnt sell a battery and starter as preventive maintenance to a customer. When battery or starter did fail it was your fault because you fix'd the alt and or parasitic drain. Hence, in the old days you would write your recomendations on the R.O. what the customer might experience. You said earlier this was an aftermarket alternator, we've all bought aftermarket alternators w/out issues - but not knowing where it was bought is an unkown variable. Before Autozone or O'Reilleys there was Chief Auto Parts. Chief had the alternators and starters rebuilt in Mexico; the prob with their rebuilds is they only replaced the broken part and never did a complete rebuild. It was normal to go thru three alternators or starters before you finally got a good one. So when Autozone came along Chief Auto was pretty much put outa business. Autozone, and O'Riellys, completely rebuilds their units atleast they did early on. Now we have to deal with Dorman, Cheap Korean stuff, and cheap Mexican stuff. Dont go cheap when buying Alternators or Starters: and get the lifetime warranty. On my vehichles I always always fit a 1000 cca battery when the old one fails. Sorry for the long post. Im going with a faulty aftermarket alternator or a broken crusty ground in the Alternator circuit. BTW, I've had alternators that would not act up on me over time left someone stranded. I still remember a Lincoln that did this three times. Always acted fine after removing it to be bench tested - it always tested good, heat related (who knows). Finally talked the owner into "just replacing" the alternator as every piece of data kept pointing to the alternator. New alternator fix'd the problem.., was this a win for the Parts Cannon😂

[@brianloftus3574]

Case of alternator not a good enough ground to engine block

[@NVRAMboi]

Thanks Ivan. No idea what's next, but as a former (happy) Subaru owner, I'll be surprised if it's not something fairly simply causing the erratic behavior. Can't wait for the next video.

[@Nemesis-yn5wv]

I’m suspicious about grounds too.

[@CharlesLease-ei1ee]

You’re just pulling bullshit. Questions out here, rabbit hat I don’t see a ground in doing that. It’s pulling too many amps. You could see that clearly because it basically almost kills a motor. If you don’t know, don’t throw the questions in.

[@CharlesLease-ei1ee]

And you have to do testing you can’t just gas and oh it might be there so it might be that that’s why you have to troubleshoot. I used to do that, but in the ass too many times looks like that or maybe that or I’ve seen it on another vehicle, Cos scope meters scanners. Look at data test, troubleshoot check voltages do all the testing in the world don’t throw the parts canon add it it always get you in trouble learn how to read the data in the scanner.

[@charlesadams41]

"What would you do next?" Me: Take it to Pine Hollow Auto Diagnostics 😅

[@hikerJohn]

😂

[@mattsuotoko9443]

😂😂

[@watsisbuttndo829]

I had a early forester that ran poorly , i did a comp and leakdown check, replaced plugs and leads, borrowed a coil set of a guy at work. Unplugged the alt, unplugged and cleaned all connectors in the engine bay. Took it to three different subaru specialists. No joy. Ended up fixing the problem by selling that turd.

[@PineHollowAutoDiagnostics]

​@@watsisbuttndo829bummer... The 1st gen Foresters were pretty cool 😊

[@watsisbuttndo829]

@@PineHollowAutoDiagnostics mine was a POS. The 22R powered LPG fueled hilux i had at the same time was more powerful. It drove like it had no ignition advance, wore out its gearshift linkage, split CV boots, failed an injector, failed a plug lead, and then the clutch started slipping. All under 180,000kms. The hilux i had at the same time only ever failed to get me home once in 518,000kms.. no more subies for me!

[@ThunderbirdRocket]

Very intriguing / challenge ! Looking forward to seeing / learning more !! 👊🏼 🔥

[@RJTC]

That noise and spike level is crazy when the alternator is connected - on both 12V side and coil ground. I'd not be at all surprised if the spikes are causing problems or messing up sensor signals.

[@MrOverstuffedcow]

I don’t know why resistor pack comes into my mind or if this year of Subaru has one but I’ll guess it because you’re Ivan and I already know it’s fixed. Great video.

[@brianmarshall948]

I would check the charging current when the alternator is plugged in, it sounds like it is trying to charge very heavily. Love your channel, wouldn't miss an episode, thanks.

[@nicholaswatson3896]

Replacing the alternator cured a rough idle on my Volvo V70 D5. It also transpired that one of the ABS sensors was unplugged, but only threw a code after the new alternator was fitted. Most strange 🤔

[@StevenDaugherty-uo5cs]

I would do two things. 1 determine which coils are dropping out and 2 find the parasitic draw. Look for common interface. What is pulling the power away from the coils. It would also help to know if this problem existed with the original stock alternator.

[@scotts4125]

I'm thinking it did that's why they replaced it but it didn't fix it.

[@SiteReader]

Great analysis. I was ready to condemn the engine ground, especially after seeing the appearance of the battery connections with rust on the battery clamp nuts. (Why can't people just clean them and coat with vaseline? My batteries last 8 to 10 years in the Northeast with simple maintenance like that.) But I would have been dead wrong. That's the difference between my dumb-assed guesses without careful oscilloscope work, and what you do.

[@roxanneabbott8424]

I love your videos because I know if anyone can figure it out, it will be you! Waiting anxiously for part 2 Ivan!!

[@expertmax32]

I had a similar issue on a subbie, the cause was a poor ground at the ECU. The MOSFETs that drive the injectors are working at 5V. When the battery voltage went above 12V and because of the high resistence of the ground on that voltage regulation circuit, it would create some sort of a weird RC feedback and thus mess up intermitently injector drive. Next steps would be to check powers and grounds at the ECU and check for good injector drive with a noid light.

[@stuartelsmore]

Alternator is the issue, had this a couple of times. Usually pops a cam code, if you scope the amps output from alternator you will find large negative spike, I guess must confuse the ECU. Good luck. Stu from NZ

[@hnd2893]

There are 2 engine harness grounds right on the back of the driver's side intake at the cylinder head. They may be loose or corroded. Had an '08 Subaru recently, non-turbo, a failing ignition coil was feeding high Kv's into the 12 volt system, with the alternator plugged in, evidently it was enough load on the engine to cause coil break down. With the alt unplugged, the engine idled fine.

[@aranhaydar9195]

Ivan knows how to make us anticipate his next videos, & it hurts 😢

[@anibalrivera7529]

Tanks for sharing, i guess the polarity of the alternator gets backwards when you plug it in do to some short to -/+

[@AK-Ram-tech]

Man thats cool! Im curious to see what you find.

[@derrickjacobs3375]

I bet it has something to do with the parasitic draw on that 15 amp fuse. What circuit is that fuse in, what is the draw, what is the draw with the alternator plugged in and what is the draw with the alternator unplugged. Something is probably jumping to ground in that system

[@johnmeyer6537]

I am going to bet that the parasitic draw has something to do with it since it is a B+ circuit. Shorted wires.

[@kevin9c1]

I haven't finished yet but you could mimic the alternator with your Top Don power supply. Connect positive to the alt output and ground to the alt chassis or closest equivalent ground point. Turn power supply on and off and see if the results match. If so your ground theory is sounding very good. Make sure to probe the worst coil and check positive and negative. I would assume you'll find something and then troubleshoot why the positive is being pulled down OR ground is pulled up.

[@sambitar5194]

IVAN; YOU ARE SO WELL ORANIZED IN YOUR DIAGNOSTICS AND WELL EQUIPED WITH YOUR EXPENSIVE MEASURING TOOLS; YOU HIT IT ON THE NAIL HEAD LOOKING AT CRANKSHAFT POSITION SENSOR GROUND CIRCUITS AND MONITORING THE QUALITYNOF CSPS WHICH WAS FINE.

[@HamiltonSRink]

Having seen only this part so far, the test that comes to my mind: A set of jumper cables. Bypass vehicle ground by placing black cable onto battery negative, taking other black cable end to alternator housing.

[@kevinmills5293]

Cranking sounded weak to me so I’d check for poor engine to chassis ground. With the alternator working, the engine ground could be getting raised. You could use the charger with the negative connected to the engine block and see if it does the same thing.

[@denrayr]

What if the coil you're reading the ground on is one of the ones that's still performing? Next, I'd run the same test on the alternator case. This car reminds me of the one that Bernie had that had the ground modified and flowing across the crank. If all other ground checks are good, I'd install a temporary ground from the alternator case to the battery. If that fixes it, I'd be back to looking at the ground path. With multiple ground paths, it could electrically test good, but be flowing on the wrong path.

[@diodadioda]

Make your own alternator harness with test lead, indicator light and disconnected wire to the ECU. If everything returns to normal, that's where you need to look for the problem.

[@martinvaldepena48]

I installed a Subaru 2000 2.5 in my 1986 vw vanagon I’ve been fighting this high idle stays at 1500 rpm’s no matter what I do. Replace it did drop when I replace throttle body and rpm’s did drop but didn’t last i do have the Subaru harness on this swap thanks for the awesome videos you.

[@PatOne09]

Bad diode or short in the charge warning light circuit? Lots of scrolling on my phone, but based on the clues you revealed - 1 reasonable DC output 2 parasitic draw 3 runs well when 13.6V @ 18A applied directly to battery. So i looked for diodes in the circuit between the Alt and a 15A fuse - "combination meter" charge warning light. If correct, who'd think to link the cluster with an engine running on 2 cylinders? Great video as always Ivan & thanks for the puzzle!

[@190055joe]

Greetings from Australia I would be tempted to put a capacitor on the output to GRD of the alternator just to see if the AC ripple is causing the issue .

[@carsten4594]

What would happen if you removed the alternator belt? Does the alternator lock up like an electric brake?

[@dragoscristian9856]

You când take the little belt off and start the car If it tuns ok the problem îs grom alternator spinning, possibly from the magnetic field gennerated when spinning. I have seen 2 card with similar problem a Fiesta and a Smart .The cars can't be started, they run on spray fumes and all the mechanics tought that was an injecții pumps problem! You când check the voltage with a multimeter at the battery and see If it varies much, i've seen cars that puts 17, 17.5 volts with bad regulators! My guess its the rectifier bridge faulty in this alternator If it is original piece, If not original change it with the original one, 3 wire Smart charge controlled! The electromagnetic brake output for generating curent is out of the limits and i guess the magnetic field of IT.

[@carsten4594]

@@dragoscristian9856 The alternator has already been changed. I'm wondering if the problem still exist with the alternator not spinning.

[@Sandmansa]

I've never seen anything like this either. Yup, mind blown. That's nuts! But something tells me we are having a poor ground issue here somewhere.

[@rjm7168]

I'd check the grounds, including ground cables. Once had a battery main ground cable that was corroded in the crimp fitting. Took forever to find it.

[@jeffmiller6100]

Wow ! The previous Work and money spent has to be substantial. Now the back check of all work done just to make sure all the parts hung on it are good and installation Correctly completed. Then .. Ivans own Diag.. This is going to be a good one❤

[@partsshooter]

My curiosity would wanna test ground temp... and what would happen if the maintainer was moved to engine/alternator vs directly on the battery🤔 nothing would be touched or distributed attempting this. I can understand that the alternator take up a load once excited and could place ground circuit in a deficit

[@johneslaughter]

I would try enabling the alternator by bypassing the connector. Assuming the regulator is internal. You could use your bench supply to vary the excitation and delivered current and note the effect.

[@glenharper3136]

Thanks for the video Ivan.

[@arcadeuk]

So my first thought at this stage would be to pull the ecu fuse and feed in external 12v DC power ideally from a variable power supply to see if either 1) The ecu is being sensitive to ripple from the alternator, or 2) By turning up the voltage on the variable psu to see if the ecu starts dropping out when it sees 14/15v

[@jdesaavedra0432]

Ivan, there is always a look of delight when you say something is crazy. It's kind of like Dr House saying "interesting!"

[@autodiagyt]

Im behind on videos but after seeing the symptom my thought is the alternator cable possibly shorted to ground and when it’s plugged up it’s just loading the engine because of the current draw.

[@howietorock]

always start at earth connections seen wierd things with bad earths also trailer plug bad wiring and or aftermarket things like led lights,stereos,speakers etc etc

[@Eromatic]

Engine grounds are quick to test with some jumper cables. But I do wonder what kind of current that alternator is putting out as to if that is electromechanical resistance that is being seen, and if so in to where is that energy being dumped into. If it's really high on the amp clamp, I'm sure that a thermal camera could pick out the hotspots in an instant.

[@baxrok2.]

Thanks Ivan!

[@stevejakobsen2765]

A few days ago one of my guys changed the alternator on a Volvo of some sorts Im not sure if we diagnosed it or not, but it was bad apparently. I just walked by as he was starting it up and i noticed there was a new battery on it. Which i know we did not put in. My gut told me to check the amp output on the alternator so i fetched my handy smaller ampclamp which max out at 100 amps. That clamp did indeed max out on the alt. wire. Told the mechanic to put the battery on a charger for a few hours so we didnt burn the new alternator out on the get go. Cause it looked like thats where the majority of the amps went. To the battery that is. So he did. I went over there now and then to check on it and monitor the amps and it turned out the battery could take whatever the charger could throw at it if i turned it up. 60 amps in this case, and it did not go down much in the time we charged it either. The battery didnt even get hot. It was so weird. We put a new different battery in it and it was all dandy. What is the relevanse to this case. Well... lots of amps need a clear path all the way arround the circuit. So a badish ground could have done some weird stuff. I know it started ok but still... That case just popped up in my mind when i saw this vid...

[@andrewsweet43]

Maybe the alternator output is somehow shorted (bad rectifier inside?) and loads the engine. I would connect the big alternator positive on an external battery and measure the current it sends out to that battery with a current clamp. measuring the output of the alternator for ripple with the big car's battery connected may be misleading because the battery may "eat" the ripple (behaving as a capacitor). Also is the alternator the right part? If it is the 3Liter version, it may require the PCM comm wire, and the abcence of it may cause the alternator to full field by default and bog the engine down.

[@ulfg1409]

As we know that two coils get far less current when the problem is active I'd check voltages throughout that circuit to see exactly why the current goes down. I'm assuming that would lead to finding a voltage drop somewhere, or possibly a computer going nuts.

[@kennethnichols7263]

What is the system voltage with the alternator plugged in? Can you raise to that with your battery maintainer with the alternator unplugged to see if there’s something that sensitive to a higher voltage?

[@LSmiata]

Interesting case study. Is alternator on a CAN-bus? Is it possible alternator is being commanded high amps when engine at idle??? Could remove belt and confirm. Had very different issue, but related to in-vehicle network with my BMW E60. Alternator not working because CAN-bus pulled down by faulty oil level sensor.....grrrrr! Waiting for final outcome. Great video as always!

[@matsbengtsson3756]

I had the same problem on a Ford many years ago. Problem was a bad diode in the alternator causing high ripple on the 12V. ECU did not like the ripple and went nuts. New alternator fixed the problem.

[@musicalgreasemonkey]

Check cam signal? This reminds me of a Bernie ATS video where the camshaft was magnetized due to a missing ground strap from the cylinder head to frame rail and the cam signal was being inverted at a certain engine speed. Maybe instead of a certain engine speed altering the cam signal the system voltage is. To answer the question at the end of video I would check cam signal next.

[@derrickjacobs3375]

Also, this just popped into my mind. If you can check the voltage on the fuel pump with the alternator plugged in and not plugged in and see where that takes you.

[@thirzapeevey2395]

I have no idea on these electronics, but when you showed a fourth wire that was only on the 3.0 liter engine, I started wondering if they had put an engine computer from the 3.0 liter engine on this car, and it is missing a wire?

[@millerfawaz151]

Raise the system voltage while running using the maintainer to alternator levels. Check cam sensor signals. Jump the battery ground to the engine. Do a voltage drop test to the block during alternator connection. Not in that order.

[@htownblue11]

Coil ramps when alternator plugged in suggest a fluctuation in amperage which suggests an ac fed source versus dc and returns to nominal when the ac curve cycles. Either that or ground isn’t allowing higher amperage when plugged in causing the system to go wonky.

[@gregdawson1909]

I would disconnect the main power lead leaving the alternator and check voltage there, could be a bad rectifier causing ac current to flow to the car, if the pulley size on the alternator is close enough that the alternator poles are synchronized to the engine ignition events you could be seeing negative voltage on the dead misses, and positive voltage on the hits.

[@fredautos]

Crazy case Study I'm still suspecting a bad ground somewhere!

[@matthewmcmaster2731]

I'm going to throw out a pretty vague guess as to what I think it might be. There is a wire somewhere with failing insulation. With the alternator disconnected the power flowing through it is low enough to stay isolated and not cause any problems. But as soon as the alternator gets plugged in that faulty insulation can't shield the wire anymore and it's getting grounded out.

[@wino99999]

There's got to be a bad earth possibly on the ECU as there doesn't appear to be a problem with earthing to the Coils, Something has got to be floating as soon as there is any ac ripple or once there is a significant current flowing into battery.... however, I would also look into the current drain to identify where this actually is - I wonder if they could be linked.... (interesting that the engine gets progressively worse when alternator initially plugged in. As well as the 1st good current ramp takes 3 more steadilly increasing ramps before getting another good pulse) First check the basics - Power and Grounds plus identify where that parasitic draw is! If the signal are getting weaker when Alternator is plugged in, thats got to mean the current draw into battery from Alternator is causing a Potential difference (something is floating) across a bad joint somewhere (Power or Ground but most likely Ground)

[@bradfaught1695]

The parasitic draw is usually the hvac unit in these. Not really sure what direction to go on the alternator, I like going after the coils, but now that you know your losing amperage but the fires are still visible I'd have to ask where's the power going? Alternator is working, could still be a ground issue. Maybe run a separate feed to the alternator like on a old gm alternator since its not a smart charge system?

[@colchronic]

That's very interesting One thing I did notice is the first and second coil are completely dead when plugging in and the third one is only like halfway powered and then the fourth one is completely powered so is it some kind of time related thing. Also there are some interesting things that I noticed the parasitic draw for one and also the battery having 20 amps but not being able to crank. I'm very suspicious of a bad ground break out your thermal camera and check the grounds for heat

[@chrisjackson9102]

Maybe coil power shorted to field power? Maybe see if they are supplied on sep circuits, and if so measure current on coil circuit.

[@abdouallahuniverse5689]

The connector wires to the regulator has problem, may be a short somewhere between them and others electric wires or between them only on the.wires harness.

[@seventhladderautosport]

“Today we have a really weird car… it’s a Subaru” … video over enough said 😂

[@russellhltn1396]

Not sure what's going on, but a few checks I'd make. You say one side of the crank sensor is ground. Is it grounded by the ECM, or is that line shorted? What happens if you pop the belt off? Does it still malfunction with a non-spinning alternator connected? Like wise, what happens if the alternator is spinning and plugged in - but the battery lead is disconnected (no amps)? What if you crank up the battery maintainer to get the alternator to back off? I do wonder about the magnetic fields from the alternator affecting the sensor. Those are quick checks that would provide clues.

[@SHSPVR]

That is totally insane I know alternator can do weird things but I've never seen one do this I'm kinda wondering if you got some kind of a loop back feed on the ground though as long as the alternator is not plugged in it is probably grounding backwards perhaps there's a wire that melted between the two and causing,

[@markusedma]

Bypass alternator plug (go direct to alternator) white/red with fused battery voltage and test light for alternator warning signal to isolate problem to vehicle or to alternator output.

[@fredsalter1915]

That's what I was thinking, too.

[@n6dl321]

I would unload the alternator and verify the running affect continues with the rotor energized or not.

[@calholli]

I've seen similar to this with an electric motor.. which had internal coils shorted. But the fact that this alternator is brand new, makes me think that your main output wire on the alternator is shorted. The first thing I would do is unhook your main lug on the alternator-- and then try it again and see if it still bogs down the engine... If it no longer bogs down the engine, then I would trace that main charging wire and see if it's shorted somewhere.. I think the fact that it's dropping coils is just a weird side effect; maybe it's supplying so much power to the "ground" by being shorted out, that it's virtually removing the ground of the coils by floating a voltage on the ground side. but I'm super interested to see what it is. :) ........ I'm thinking that main lug/charge wire is disconnected from the battery (or it goes through a blow fuse).. but is shorted to ground somewhere between the alt- to- battery run. I have a similar issue just like this on my 2005 ZZR.. The coils have very weak spark and I'm not sure why.. I put on new coils and it didn't fix it. I'm not sure what's going on just yet. So hopefully this case study will give me a clue. I'm looking forward to it. :)

[@walkertonheights]

You showed how the spark current (amps) were not the same for each cylinder. I would like to see if the fuel injector current does the same thing.

[@phildion8010]

My next diagnostics would be try another alternator. But that was my first after voltage checks were good.

[@ricardobranco7357]

Had similar on my KTM, the stator had shorted to ground but at idle it worked as you reved up it got worse, misfiring etc, it'sa FbW throttle and it was not acting right, I was still getting some charge, very odd. Replaced stator and regrec and all was OK again. My guess was the stator was pulling the voltage down as the bike reved up as it was grounding out. Odd stuff.