BMW actually calls this communication wire BSD (Bit Serial Data) bus, but it is in essence just LIN bus. This E83 X3 is built on the electrical system of the E46 3 series and adapted to fit more modern drivetrains like the N52 engine in this car. On newer models like the E70 X5 or E90 3 series the intelligent battery sensor and electric waterpump (depending on what engine it has) are also connected to the BSD bus besides the alternator and the oil level / condition sensor. Also by knowing how the system works you could have skipped scoping the BSD wire but rather just unplug it from the alternator. On any BMW with a BSD alternator if it loses communication with the DME it starts charging at full output as an emergency strategy. Going into OE diagrams and reading the functional descriptions is never a waste of time ;) The voltage drop test on the B+ wire would have sufficed for this diagnosis. But as always excellent video Mario :)

@lynxstarautomotive208

2 ай бұрын

Very true 100%. Always hilarious when a caked in oil, oil condition sensor crashes the BSD and the car comes to you after it’s had 3 alternators installed elsewhere.

@arnobruynen6073

2 ай бұрын

@@lynxstarautomotive208 3 alternators? lol I had a car come in that had 3 DME's installed!!! one of the DME's they were trying to swap in actually got fried when they accidentally touched it to the jump start terminal and hadn't disconnected the battery 😂 Started with putting the original DME back in, scanned it for codes, BSD fault off course. started unplugging BSD components while scoping the BSD line. at first it was at around 6v amplitude and really noisy signal. Unplugged the oil level sensor and the signal came back to a 12v square wave. While ordering a new sensor I actually found they installed a metal housed Hella oil level sensor while this car needed a Temic plastic housing oil condition sensor. the sensors had different pinouts, that's why it pulled down the BSD signal. Diagnosis literally took less than 30 minutes, so much for parts changers!

Excellent video Mario , 99% of the time technician will just slap in alternator but what if it doesnt fix it right Just want to share a quick story , we had a tow in Lexus gx460 one time at the shop and my coworker told me just slap a starter at it and because the vehicle was outside the shop we had to push it inside the shop , I said no , I need to do my checks . Long story short I crank the engine by hand and it will get stuck. Found that one of the cylinder has dropped a valve 😬

True Automotive technician.

Parts changer's job is very hard when it comes to European cars, experience is their only friend.. but especially European cars you really need to diagnose! Great diag video, thanks for sharing!

Great video Mario! Thank you for sharing

Appreciate the tips

Excellent video.

Thank you

Great explanation and thanks for the time to do it in details..cheers bro

The scope is needed to verify how much the computer is telling the alternator regulator to switch on and off, plus the percentage of on vs off time. Scope for the win! Thank you for this video Mario!

Thanks for the video.

Mario, You rock brother as they say test do not guess and do not be apart changer as scanner danner say as always thanks for sharing.

Mostly the pink is BSD communication bus wire , welldone

great video baby!

I agree with 100% that this is the proper way of doing it. My experience has been that employers looked at me as if I was wasting time unnecessarily when following proper procedures.

Another good video why you should check instead of assuming I would like to see how you set the scope up

you mention ground being same for starter and alternator which is correct BUT corrosion between alt housin and where it mounts could cause issues great video though thanks for the content

@SuperMarioDiagnostics

2 ай бұрын

Bmw’s are naturally corrosion proof thanks to their inherent oil leaks

@jordanboulay3780

Ай бұрын

@@SuperMarioDiagnostics agreed plus you live in florida not the north

This guy is a brain

Thanks for the straight forward diagnostic plan. What scope are you using? Maybe a link to it. Looking for a multi-channel scope, that's a little less expensive than a Pico.

@VWERIC10

2 ай бұрын

Just found your review of the MICSIG SATO1004. Thank you.

I'm guessing the alternator was the issue, even though the LIN signal was good? From the footage, it appears the signal was okay.

The Lin line signal was not marked on the diagram. If there was a short to 12V, how would you know it was abnormal?

@SuperMarioDiagnostics

2 ай бұрын

Because the oil condition sensor is also connected to that line. This proves that it’s a communication wire. If it were shorted, we should see several symptoms, including a check engine light and communication codes with both the alternator and the oil condition sensor

Yes this is important stuff when you offer automotive service to the public. Too bad i've seen some bad comments. I hope these guys dont work on other people cars, especially if they're charging money.

after all, was it a smart charging system or not? do bmws only charge 13.8v? or does the voltage go up when you put consumers? because i see it charging 13.8v with the lights on

I changed the main battery on a 2019 BMW X5 the next day my customer called me and said the car engine started on its own while in the garage. Have you experienced this before?

What scope is that Mario?

@SuperMarioDiagnostics

2 ай бұрын

Micsig sato 1004

Where are you located at? Will like to take my Mazdaspeed 3 , been having a problem with it, nobody seems to find problem.... thank you

@SuperMarioDiagnostics

2 ай бұрын

Ft. Lauderdale

@Dan-vt1qt

2 ай бұрын

@@SuperMarioDiagnostics forr realll! Thats awesome im moving out of the state, so before i want to have the speed 3 fixed, whats the name of the shop , or how can i contact you to take my car thankss

“Parts Changers” get a bad rap, sometimes. For example: if I have a check-engine light and a code for a bad O2 sensor on a vehicle with 100k, I’m not going to waste time checking for power & grounds, etc. I going to just change the damn sensor.

@SuperMarioDiagnostics

2 ай бұрын

Even when that sensor is 500+dollars like on some cars?

@thesmartguy3523

2 ай бұрын

​@@SuperMarioDiagnosticsit's JUST $500 if it's coming out from the customer's pocket from what it seems 🤣 these parts changers will never cease to exist it seems, more work for those that test!

What can I say, common sense. Alternator is not charging then replace it. Plain and simple. I just unplug the ground cable (black) from battery and car keep running then is not alternator, otherwise it is.

@SuperMarioDiagnostics

2 ай бұрын

That’s a sure fire way to brick modules nowadays. This isn’t a car from the eighties

@thesmartguy3523

2 ай бұрын

100% agree​ with you Mario@@SuperMarioDiagnostics - crazy how stupid some can be 🤦🏻‍♂️