Check out my website ; www.diagnosedan.com For the Topdon tool used in the video: US:www.topdon.us/collections/pro... UK: www.diagnosticconnections.co.uk/ EU: eu.topdon.com/products/phoeni... For business inquiries ( not for technical questions); Diagnosedan@gmail.com

It is appalling to me that if the dealership can't diagnose a fault they start replacing parts at will on the customer's cost, even if those very parts don't fix the fault.

I can’t believe the dealer and an independent mechanic couldn’t figure that out. The code points you right to the problem. Well done Dan!

I work 9 hours in the workshop. At the end of the day I still enjoy looking under the hood with Dan . Thank you for keeping it logical and simple . More diagnostics please 👍🙏🏽

Diagnose Dan + a BMW = the best part of my week!! You the man Dan!

The more things get complicated the more they stay the same in some circumstances….. Great diagnosis Dan.

When the dealer can't fix their own cars, you know they're too complicated.

Great diagnosis, Dan! First time I see a starter motor driving a timing belt haha I've seen premature starter failures recently, mostly in Subaru and Honda cars. Maybe Denso quality is getting worse :(

You and South Main Auto are two pearls of the YT diagnose world, keep on doing it !

Marvelous diagnosis, Dan. Can't believe that the dealership was satisfied with only battery replacement and didn't test further. I really liked the hammer testing of the solenoid. The 12V sort of classic starter motor makes sense how you explained but complicates things. Keep up the good work, we are loving your videos. Thanks

Disappointing that a 'BMW trained' mechanic couldn't resolve this at the dealership. Well done Dan, you did it again! Fantastic bloopers by the way 🙂

That takes me back many years in giving the solenoid a whack to try and bring it to life, cheers Dan.

I'm I the only person that thinks that start stop system is stupid in none hybrid models. This channel and scanner Danner are the best educational automotive channels on KZfaq.

One of my fav automotive diag channels. Wish you made more frequent videos but I understand the real world lol

Dan is not only a good electrician/diagnostician, but also a skilled mechanic!

This is my second time watching this. It's fun watching a pro in action. This stuff is better than tv.

The hammer trick on the starter never fails 😂😂. Good job as always Dan.

Just as with Eric O. You are the last but best resort. You'd make for a excellent teacher also!

Very nice video. I am not a mechanic but I have a theory: Maybe the BMW engineers put a starter motor in case the hybrid system had an issue, so the car can still start

This guy reminds me of my late brother-in-law only he work on jaguar cars for over 40 years before he passed one of best mechanics I've met.

Always a highlight of the day, going on a diagnosing journey with Master Dan

So bad that the dealership couldn't find the cause of this problem. You just diagnosed it like a pro as always!

Another thorough, informative video. I had no idea that a BMW hybrid has a 12v starter. Another great example of knowing your enemy. If you don't know how it works, you can't fix it. Thanks, Dan!

Love all your Videos Professor Dan…..Here in the USA that car would have already been sent to the Crusher…..BMW’s are overly complicated for no reason. And the only one’s who drive them are Twinky’s that have more money than Brain’s….I am so Glad I Retired as a Master Tech in 2018 and Bought a 1970 Chevelle SS for my self and bought my wife a 1966 fastback Mustang. And we are so happy with simple but Amazing Car’s. Keep up the Good work Dan your Generation needs more Technicians like you. 🤘🏼🇺🇸🇺🇸🇬🇧🇬🇧🇬🇧

16:05 Another interesting and informative video, Dan. What a surprise. I suppose using a 12v starter motor means you could probably jump start it at least if the 12v battery was dead as well as the high voltage battery. And for our buddies over in the US, here the term HV AC is the High Voltage Alternating Current motor, not your residential HVAC motor! 😂 Just poking fun, no offence!

Great job, but I am puzzled as why to replace the whole starter instead of replacing the solenoid ( relay) alone?

Long time no See on KZfaq Dan!.. I'm Extremely happy because I'll learn what a start/stop system is! Lets! go🎉

I think the dealer should have known a 12v starter battery would include a separate motor other than the 3 phase HV MG unit. Main dealers never fail to amaze my. Well done Dan.

Moral of the story, keep your thoughts to a basic level, that could fix "big/complex" problems and as usual Dan is right when he said, "get to know how the system works", that's key to fix it!! Good job Dan!👍😎💯

Another great diagnosis and fix. It is a little depressing that a company like BMW cannot find a problem like this seeing that it is their own vehicle. More videos please, you're the best.

Thanks, Dan, the video was very interesting! Usually there are two coils in the conventional starter relays - a main one (which moves the engagement mechanism and closes main contacts) and a "holding" one. It is very interesting if Denso used a conventional relay on this starter - in fact, there is no need to move any engagement parts there! I would not stop myself splitting apart that relay 🙂!

Just the knowledge of how this system works is worth the watch.

Another great diagnosis, Dan! 👏👏👏 You make it look so easy! 😜

Excellent work, Dan. As far as 12v starters go, I suppose it’s a point of failure but also a point of recovery. As you say, it won’t get stranded by the HV battery going flat, it also means any normal car can help jump start it if both batteries are flat (perhaps it’s been left for a number of weeks without charge). I don’t think a belt is the best way to go though. A chain would be better I think. No need to oil it since it would be doing little work.

Outstanding Dan! I really enjoy working together.

This guy Dan has great trouble shooting skills. He really teaches you along the way. Great video camera work also. I like Dan's videos. He makes it looks so easy when it really isn't..

That’s some great detective work and you made that seem very easy! This is why I’m a dedicated watcher of your videos Dan! Thank you for sharing!

Having spent some time in the past overhauling starter and alternators - That was interesting in that the 'Pull' windings of the solenoid were open circuit but the 'Hold' winding was ok - maybe taking the cap off it would reveal it's failure ? Great diagnosis however and correct in what you say - understand the system to correctly diagnose it - well done

I believe the reason they put the additional starter motor it's to save the power consumption on the ev battery itself and also like you said it will help it to keep on starting even if the ev battery is dead

Brilliant as usual Dan, the way you keep up to date with technology is incredible so envious of your ability to diagnose,

Great work Dan once again. I never knew they had a backup starter motor either! 👍

I really appreciate your thorough diagnosis in checking continuity on ground and power. Moreover, as you know all vehicles rely on ground and was hoping that was the culprit. Nicely done there Dan!

In some cases, things aren't so complicated like we think..! Thanks again Dan..! Very informative video.

It's been quite a while now bmw engineers are praised again. They provide redundancy in the engine starting system to avoid the car being stranded and not only that, but they also use reputable supplier as well like denso. the one way crank pulley and the easy access for repair also adding up as cherry on top. just wow 😅. good job bmw. and thank you for Danny.

Another great video Dan .. love the way you work through these issues 👍

This was once again a great example of amazing knowledge and logic. Keep it up!

Mercedes C & E class hybrids have both starter & e machine, been fixing this issue for years now not uncommon but yes many people caught out by this including a issue where the starter motor is not known to be faulty by the customer & is brought in for a engine software update & then, will not start as part of the immobiliser learning process is to start the engine via the starter, you then have the difficult conversation with the client explaining their starter requires replacing to which their refuse & state it started fine before it came to you so you own it. We now check every starter works before updating any software to protect ourselves. I believe the other reason it has both motors is when driving in electric mode then kicking down into engine drive you need to start the engine via the starter to ensure a smooth handover from one drive to another as there would be a difference in speeds causing a jerk in drive which can be felt & is the big give away to a n/w starter what most customers actually complain about a gearbox issue.

You should tag in the video F15 40e 21A515! I have been working on one of these all day looking for information on this code and this is exactly what I needed. Ours is a 2016, but we've replaced both batteries as they both tested bad, then we had three scan tools not have the option of "replace/recode auxillary battery* and the primary battery wouldn't register either. So after finally registering both batteries with ISTA with our laptop from 2010, test drove with the exact same code coming back. Took belt drive cover off to discover exact same issue. Thank you!

It is a weird failure of the starter relay. I must have an increase in resistance for it being unable to initially attract the plunger. I am pretty sure you can only replace the solenoid though.

You are one of the top professionals in KZfaq !

Being a welder & not a diagnostics guy, I see these for rear subframe repairs. Surprisingly new ones... The dealer repair quotes for rear subframe corrosion are beyond eye-watering - I repair them pretty cheaply (very cheaply) by comparison. Interesting to see this diagnosis - but I'll stick to welding on them, because sod all nobody else wants to. :-)

I would love to see a follow up with this car, excellent though work and well explained, I learn so much from your videos, complex problems can be simple when proper technique is used, also something i do when testing starter systems, is to retest the battery from the starter, and compare the reading that I get from the battery test, showing up faults with the high amperage cables,if there is a fault present, thanks again for a great video

Another great video Dan! I enjoyed that. Great presentation skills. Only thing I missed is you dismantle the relay/ solenoid to show what was wrong with it.

My first video to understanding about start stop in hybrid really enjoyed

Good diagnosis Dan, but its remarkable BMW didn't check this first. As usual I'm impressed with how incompetent the dealers are.

Love watching your videos Dan. I'm learning so much about the different systems fitted to new cars. Many thanks buddy 😎👍

Wow. Been waiting ages for a video from you. Always love your diagnosis methods

Redundancy is the name of the game, product knowledge goes a long way and older models may not be in newer technicians repertoire, thorough diagnostic practices as you keep reinforcing are fundamental to success, also not being too pig headed to ask others for help helps too

Diagnose Dan is the Don of Diagnosis!

Yeah it’s been a while Dan🎉

The only hybrid vehicles that I have worked on do have a 12V starter. They have the starter at the rear of the engine so this might have escaped me if I was expecting to see a starter at the rear. Well done Dan.

Old school hammer trick to get a starter motor to work. Priceless..

You‘re right. A friend of me couldn’t start any more his Mercedes because the hybrid battery was bad. He had to replace it (17.000 €) and couldn’t use his car meanwhile. The construction if this BMW made sende, you can drive without the hybrid system. But: No hybrid is even better. 😂

Guess you can't buy that solenoid by itself...

Maybe other benefit of using 12 volts starter motor is that I saw in video: while you driving without combustion engine and when car turned on the combustion engine, engine automatically jumped to 3000 rpm. It's not good if the combustion engine is not warmed up. Try to do the same with 12 volts starter engine and see does this happen again.

DD is one smart tech . BMW replaced the auxiliary battery, and did not fix the problem. Logic and proper diagnostic steps did . Bravo Dan .

One possible advantage of the 12V starter is a gentler start. The first thing I noticed on the test drive was the engine went from zero to 3000 rpm, but then came down to 1000. Not the way I'd like to start an engine.

Our Dan is the best as always!

Very smart and intelligent, Starter used when HV battery low and other main reason to save power consumption from HV battery when starting engine. I believe in some early hybrid, Honda uses it similar to this BMW, except it is not plug -in it called IMA...thank you sooooo much

Always a good day when DiagDan drops a new video.

I have seen this exact issue but I can almost guarantee it took me much longer to figure out and I definitely didn't go to the same lengths to really narrow it down like you did. I hate working on BMW's.. when they go wrong, they tend to go spectacularly wrong.

Thank you Dan for showing us the trouble that even the so called "experts" could not solve.

Great diagnosis. Loved the end part. Just shows us subscribers how much effort you put into doing your uploads many thanks super Dan 👍🏼

A lot of fault finding work for a relatively simple piece, but one that has a big impact it seems. Good luck Dan and to as many "healed patients" as possible 🇷🇴

The solenoid has two windings. One heavy one to pull it in and a lighter one to hold it when the motor is running. The heavy winding is open.

Great job in finding the cause. The other technicians aren't skilled like you are. We need DiagnoseDans in this world.

Dan, great content, modern day car are getting so complicated, they need Dan the man to fix them!!

You make everything seam to damn easy. Every step you take when diagnosing is so obvious while watching these videos, but when you are standing with your own hands in the engine, you start to overthink and over-complicate everything. Finding that first step can be difficult.

Beautiful diagnostic as always Dan… well done 🫡🫡🚨🚨

Very impressive diagnosis. I should like to add that this trend of needing to reprogram batteries when they are replaced needs to die in its tracks. Few things are more anti-consumer and anti Right to Repair then taking a repair that is purely mechanical forcing in a locked down digital component to the system.

This shows that the biggest issue is alot of people dont slow down and look at the information they have in front of them . Nice work

Priceless diagnosis video 👍🏻👍🏻

Your miles ahead of others with your logic paths, I find it so helpful in this new system

Good to see you again dan Beautiful diagnosis as always

Diagnose Dan, Does it again and again and again!

wow i was just rewatching some of your older videos and a new one appeared just in time

It is a surprisingly smart system. It has failover lol. Nice. I mean it is surprising for nowadays when most consumer grade equipment fails outright instead of having failovers or any headroom built in anywhere.

Im not an automotive technician, but heyy i learned a lot from Dan. Tq

Hello, very good content as allways. As sombody else pointed out, the start motor might be for the case of flat main battery or electric motor failure. It is possible that an independent start motor improve confort for passengers and reliability of the electric engine system avoiding it usage for starting the engine. The good thing is that this point of failure does not compromise the car usability.

If you have to be a master tech to diagnose this, bmw are finished, great job as always

I work whole day in cars and attending some training but all those not make stop to watch your videos, your videos are so great 🎉wish to work with you to learn more from you.

Great job, Dan. You have just put the dealership to shame.

Once again it was proved that there are no shortcuts tests tests until a conclusion is reached. I learned more about the hybrid thank you Dan.

I'm a personal trainer and watch all your videos...i knw little about cars but this is still good viewing

My car a 2013 Chevrolet Malibu Eco has a mild hybrid system that also has a 12v starter and a high voltage starter. It uses the 12v starter i.e. when you turn the key and the high voltage one for the start/stop system, this allows to start the car even if the 12v system is discharged, keep in mind that the high voltage system is monitored by and activated by the low voltage systems in the car. EMS can cut the 12v battery cables under the hood thereby shutting down the high volt cables running under the car into the trunk allowing them to cut the car in half if needed without worrying about electrocution.

Great work Dan! The solution was easier than it looks at the beggining. Unbelievable that dealership couldn’t find quite simple issue of the problem, especially while pc diagnostics indicate where the problem could it be.

Hi Dan …. Been watching you for years from uk ….. always good to see a master at work and master of his trade … keep up the excellent work

Another brilliantly explained diagnosis on a complicated hybrid starter system. Like you said research and understanding of the system you're working on is key to diagnose what looked like a very technical issue, but only turned out to be a starter solenoid. Well done, you really put the main dealers mechanics to shame.

Hi Dan, nice to see you again! Thank you! If this were my car, i would replace the relay with a used one. No need to buy a new starter motor.

The 12v starter allows the electric motor to not have the additional load of cranking it over as it drives electrically. With the additional starter the transition from electric to electric and gas or electric to gas only is smoother. Also like you mentioned it’s an added fail safe