CAN Bus High Resistance Short Cirtcuit | CAN Bus Diagnostics | Mechanic Mindset

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Let's short the network together and see how much resistance this Powertrain CAN Bus network can take?! This test will help you identify CAN Bus Faults to make diagnostics easier. Here I use the PicoScope 2204A to obtain CAN Bus waveform while we dial in a resistive short circuit fault across CAN high and CAN low. The tool is called a decade box and it allows us to select a vriety of resistance values. We are performing this test on the high speed powertrain CAN bus network.
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27 сен 2020

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Комментарии : 53

@MechanicMindset 3 года назад

Check out this video for an intro to CAN bus diagnostics! ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-f2uPhKd-ETI.html

@JoeBob79569 3 года назад

I initially thought you had the box "in" the circuit, and I was confused when you started at 9999 ohms and everything was perfect. It wasn't until my dumb ass realised that you were slowly shorting the circuit that it made sense. Good job..

@MechanicMindset 3 года назад

Haha, cheers. A diagram might have helped! 👍

@HerrDagerman 2 года назад

FirstName: I was thinking the same thing. Your comment helped me understand. Thanks

@CarsExposed 3 года назад

I love this tests Darren super useful in making you understand the waveforms ... top man cheers 👍👍👍

@MechanicMindset 3 года назад

Cars Exposed Glad you enjoyed it mate, so many different cases for CAN bus faults, I can be difficult to work out your issue! 👍

@tonyfremont 3 года назад

I like the way you do things. This is the best way to learn. I found out, about 20 years ago, that just asking 20 experts (real ones, not pretend) would just get you 20 different guesses. They would know the guaranteed minimum resistance from specs and datasheets, but probably never saw a real life example. It's just best 5o see for yourself when you're curious. Of course this is only one specific example, but it's one more than most techs or engineers have actually tried.

@MechanicMindset 3 года назад

Thanks for the feedback! I have found exactly that in the training world; people have different opinions on how they think it works, and not all of them can be right 😂. Even I have argued my side and turned out to be wrong - so many variable in the automotive world!! Thanks for watching 👍

@tonyfremont 3 года назад

@@MechanicMindset I did a PIC microcontroller project over 15 years ago. I wanted to see if I could "steal" enough electricity from a telephone line to power the micro and an LCD display. I was absolutely assured by "experts" of everything from it's impossible to take any useful amount through I would absolutely be disconnected from the phone company permanently. Turns out that I could take several mA of current without creating an off hook status and absolutely nothing happened with the phone company. One guy contacted me privately and explained how he built a "down hole" type battery powered device (actually a street manhole) and connected it to an available phone line. At night they would call the device and suck the massive 100+ volt ringing signal off the line and recharge their batteries by letting it ring for hours. The phone company never noticed a thing. You'd think they'd pick up on some phone line ringing for hours on end on a daily basis.

@MechanicMindset 3 года назад

tonyfremont Haha, that’s amazing! I would have never thought of that; very creative! 👍

@tonyfremont 3 года назад

@@MechanicMindset that's what I thought, recharging from ringer current was genius. I learned so much from those guys, it was better than going to school. The really clever guys learned their hands on skills fixing pinball machines in their younger days. No schematics, or at least none that actually represented what was really happening inside them when they had to fix them. Game room props taught me just how creative people can be at inflicting damage to my "art work". I'm seeing a lot of the same kind of experience watching guys like you and Eric O diagnosing problems and undoing other people's "clever repairs". Theory is just that, it sounds reasonable, but the real world is never really included in a schematic. It never dawn's on a newbie what really happens when you turn on a switch, it goes on and off dozens of times before it settles down. You don't see it when a light bulb comes on, but a computer sees it every time and has to cope with it. None of the datasheets or other documents bother to mention all that other spiking and whatnot on the CAN bus, they just have pretty pictures of a waveform that will never match what you'll see on a scope. Automotive electrical environment is the absolute worst, it's everything but a steady 12 volts, just like ground is everything but what you find at the battery terminal marked - It really is a marvel modern cars actually work at all.

@TheBMWdriver Год назад

I found you because I need to learn this for my exams, your videos are really helpfull! Thanks, keep up the good work :)

@mike-yp1uk 11 месяцев назад

I like these videos because I get familiar with cann and it's abilities and no risk to having to buy computers. Lol

@TheGibby3340 3 года назад

Hello Darren...The old school decade box ...still a great learning tool. Good Vid. Cheers 👍

@MechanicMindset 3 года назад

TheGibby3340 Yeah really pleased with this one, so cheap too! Glad you enjoyed it 👍

@billytremoloband7456 3 года назад

Looking forward to watching this video when I finally get home tonight back to Cork.

@JoeBob79569 3 года назад

As a fellow Corkonian I can definitely recommend watching this in Cork as opposed to anywhere else..

@billytremoloband7456 3 года назад

FirstName LastName 😂

@mechanicmatt871 3 года назад

Great video, seeing how resistance affected the car and the waveform, Cheers Matt

@MechanicMindset 3 года назад

Mechanic Matt Cheers, yeah so many combinations of fault on CAN bus; I hope to explore them all! 👍

@johnmwangi6291 3 года назад

Thank you for your time sir..

@MechanicMindset 3 года назад

john mwangi You’re welcome!

@robertmobileman8304 3 года назад

Nice one Darren, thanks for the video and links Rob mobile man

@MechanicMindset 3 года назад

Robert mobileman You’re very welcome! Hope the links come in use one day!

@stephanevaucelles6378 3 года назад

thank for video

@alrifainidal 3 года назад

awesome video thanks a lot . hoping we can see more Can bus issues and how to find it

@MechanicMindset 3 года назад

I will be getting this out again soon - many more fault possibilities to explore!

@billytremoloband7456 3 года назад

Just finished a level 2 exam day at Jlr Dublin, Ken said to say hello.

@MechanicMindset 3 года назад

Billy Tremolo Band Fingers crosses for you, hope it went well! Ken is a legend! 👍

@cars4693 3 года назад

Very helpful 👌

@MechanicMindset 3 года назад

UNIQUE Glad you enjoyed it, more to come! 👍

@stephanevaucelles6378 3 года назад

We did the same exercise at my multiplexing course

@MechanicMindset 3 года назад

stephane vaucelles Ah cool! It is a good excessive. CAN Bus behaves in funny ways for different faults 👍

@theGADGETSplaylist 3 года назад

Good video Darren:) I have a very similar Decade Box. I believe they use some 1/4w and some 1/2w resistors and that there's a transition point between the two usages. My Mandarin isn't as good as it should be, I was wondering if you knew where that transition is on yours? Denis

@MechanicMindset 3 года назад

Ah ok, I was aware they were low wattage but didn't know they might split them that way. My manual is also in Chinese, the diagram doesn't give much away. Not sure I'm brave enough to open the lid to check! haha

@juxhinokapllanaj7645 3 года назад

You can do a test can bus tutorials in hybrids cars because not much videos not haven yet on youtube ?? Respekt✌️

@MechanicMindset 3 года назад

juxhino kapllanaj Hi, the CAN Bus network in hybrids operates in much the same way as non hybrid cars (just different modules). I would love to do more videos on EV, just got to get my hands on one! Thanks for watching 👍

@mikethomas9544 3 года назад

Great work Mate 👍 hey did you open the box to look at what Wattage the resistors were, Hopefully they were 1 Watts.

@MechanicMindset 3 года назад

Hi, I haven't opened it but I think they are 1W - certainly only for low current! Cheers!

@AN77 3 года назад

Thanks. So Ch1 CAN high to ground, Ch2 CAN low to ground, than the decade-box between CH1 and CH2? The resistance from the Decabox will than be parallel to the 120 ohms resistors in the system? When all is good you should have 60 Ohms between hig and low? Have i got it right? :-) Did you work as an educator or instructor? You do it very well.

@MechanicMindset 3 года назад

AN AN That’s right - sorry, I should have made a diagram! So I am basically shorting CAN High and Low together with the resistor box. Yes, I have been in technical training roles for the last 10 years 👍

@budj7898 Год назад

How would low resistances like these affect a battery off network resistance check? Would we still see 60ohms?

@MechanicMindset Год назад

Possibly not, really depends on how much resistance. Low resistance shorts will make a big difference

@alibatebi2161 3 года назад

thanks for video i could not understand weather you used the resistor box in parallel or series with circuit.is it possible to draw the wiring diagram. thanks. by the way i have not seen any new video from you past few months. Looking forward for new ones

@MechanicMindset 3 года назад

Hi, I had the resistor connected between CAN High and CAN Low (short together). Yes a diagram would have helped understand better; I’ll remember for next time! Yes been quite busy but have a couple of videos in the pipeline, one to release their weekend and will be filming Gagarin tomorrow! 👍 cheers

@aminuabdulqadirabubakar4438 Год назад

Well informative Video, but my question is what type of oscilloscope will you advise a beginner to start with?

@MechanicMindset Год назад

Glad you enjoyed the video! I alway suggest the PicoScope 2204a; it’s easy to use and very capable. I am launching a video soon which will show you all the accessories you need to get going for the best price. There are other cheaper scopes like Hantek that do the job, they are just a little less versatile. Hope that helps 👍

@stitchedbyfelicia 3 года назад

Hello my husband did a heater core on our 2011 ram 2500 and now we’ve got no bus coming up on our Dash not sure where he can start

@stitchedbyfelicia 3 года назад

Also our wiper blades are going crazy

@MechanicMindset 3 года назад

@@stitchedbyfelicia Hi, I would be getting my scope out to see what’s happening on the CAN lines. I think you can access them all at the Diag connector. I have some videos on what you need to look for. If you don’t have a scope, I also have some videos to show you how to read with a multimeter. The fact you know that something has happened during this job should help narrow down where you have to look for the fault. Might have caught a loom on the dash carrier or something, they can be quite sharp. Sorry, I’m not to close with NAS vehicle. Hope that helps!

@stitchedbyfelicia 3 года назад

Also it might’ve been when they were trying to weld nuts on my manifold bolts I don’t think the battery was disconnected

@stitchedbyfelicia 3 года назад

Also thank you for replying

@MechanicMindset 3 года назад

@@stitchedbyfelicia 👍