One thing I totally forgot to mention is to know your scope and the circuit you're working on! I would highly advise that if you are going to reference to CAN low, don't use any other channel grounds. Play it safe, some scopes have isolated grounds, others have common grounds. Referencing your ground to CAN low in a common ground scope while testing another circuit that is referenced to ground will short the CAN low to that ground! Attempt at your own risk.

Got to love the guy, sweaty, dirty face, under pressure from the shop, showing us how to. thumbs up Mario!

Very good point! Scope positive to CAN H and scope ground of the same channel to CAN L to get the difference between the two levels. Thank you very much!

I love all of your videos, but this one here is full of so many tips in such a short amount of time! Great job, again!

That signal looked like there was something to be concerned about, this is definitely one to remember, doing the math. Thanks for sharing this information it's really appreciated.

Tell me about learning the hard way Mario 😊😁... thank you for taking the time to post this 👍👍👍

Nothing like a good rabbit hole ass kicking to gain experience. Good info Mario!

Thank you Mario. Good job. Have a blessed and safe week.

Thanks Mario I am just starting to experience with the gave forms and you are one of the best simplifying the set ups

Nice one Mario, never scoped between the high and low before, must remember that one, cheers dave

Thanks for the honesty and wearing your heart on your sleeve as they say. I've been struggling with the application of the math channel and your trick of using the negative lead on CAN lo and the positive lead on CAN high was a fabulous find for me. Thanks. Can't wait to get back to work and put it to use. I wish I could attach an image on here I've got a couple files saved from a CAN circuit that looks like I dragged the leads across an electric fly swatter and there was no codes or even a complaint. I was just collecting known goods files and was very perplexed by what I saw. You could say it is the reason I came across this video trying to find as much info on CAN diagnosis as I could shove in my brain.

Thanks, Mario for the insight. All your videos are very helpful. Thank you for sharing 👍👍👍

Very helpful. Thank you Mario.

Wow, there are of lot of variables to watch for. Thanks Mario.

Wow! Such a good video! So jam packed with excellent info! Thanks Mario!

Thanks for taking the time to point this valuable information out to us!!

Good info, thanks for showing us the signal and the workaround.

Thank you! Great information.

You already saved me time brother truly appreciate it

Wow excellent video. Very good info. Thank you for sharing Mario! 👍

There’s lots of good information in this video Mario especially helping out other guys to stay clear of that rabbit hole that you entered. Does Matt channels are pretty awesome and I never tried using one channel on the CAN high and low like that, so that being said I learned something!

Great video man! I would have thought there was an issue for sure, great catch! I love employing the Math channel to clean it up, brilliant!

Mario, since you are grounding the scope through the chassis ground you could be picking up noise in the ground circuit. When the engine is first started the alternator output rises. After the engine warms up some the alternator output will normally drop. This could be the cause of the waveform pattern you are seeing. I have always felt it is best to ground straight off the battery whenever possible. This should help eliminate or clean up a signal on your scope. just a thought. I really like your videos.

Excellent example of why CAN is used , interference of of the communication line makes the overall differential voltage the same great video thank you ..

Excellent Mario! Well done, I use the math channel on the Pico, however did not think of / or know of going between high and low with one channel. Thanks for sharing this.

Thanks for the great tip. After wrenching for 45 years I am still amazed at how much there is to learn. If you don’t learn something new each day, you haven’t had a good day.

Awesome thanks for sharing the great tips!

Thanks for the tip Mario

Dear sir.that was an absolutely brilliant demo.i realy loved the tip ,with using the 1 channel pos and neg scope leads to measure ,the difference beetween the 2 wave forms.superb videos sir.keep up the greatvvids,steve from the uk.

Very helpful information thanks.

Good job, sometimes we learn this way, but you just got to stick with it to the end that's how you learn. Thank you

Thanks for making this video. Especially using a regular two channel scope to look at the math.

Awesome Video Mario. Thanks for sharing your experience. I like the math channel tip, Soooweeet!

Thanks man, nice video. Its good when you share your experience. More videos like this. Thanks

Great work as always Mario! Hope you are well .

Great insight 👍🏽💯. Thanx for sharing

Great video brother and great information! Thanks for sharing!

Very good Mario! Thank you for sharing this video! Thumbs up

Great video thanks dude

Outstanding.

Such great 👍🏻 information

Great video!

Thanks for showing exactly how you hook up the leads, so many channels skip this part and rookies like me get lost.

good info keep up the good work!

Great info Mario that’s really interesting I never thought about using a math channel to double check the signal. Awesome awesome video. Send it lol ... Jay

This is a life saver ,Great Video Man 👌👌

That's a good tip. Thanks for the video.

Great info once again Mario. Something else I was told if the can waveform looks a bit off is "Do the lo and hi mirror each other?" that is a good indicator for correct signal, but man I reckon that waveform would have thrown anybody.

brillint sir.

Wow! Great video Mario, looking at that waveform I would’ve definitely thought there was a problem! Great tip on setting up a math channel to see what the computers looking at. As always, thanks for sharing!

Great content in your videos bro!

Great information Mario. I ran into similar issue a few times and I chase it for a few minutes before I remember to add a math channel. Since I have a 4423 pico I have to be careful with checking differential signals because mine has a common ground for all channels. I think they changed it on the 4425 and each channel has its own ground.

Bad ground on the scope at 5:00? Almost got burned today by a similar waveform... :0 Awesome tip with the math channel!

Good video Mario. Very helpful, I need all the help that I can get with network issues, lol.

something else I've learned, thanks mario

Great tip Mario

Good information just like in all your vids . Keep it up man .

Very good video!

thanks for this video.

great info . that would have bit me for sure. thank you.

Nice Explanatión Mario because I love your chanel.

Wow, I would have sworn that CAN waveform was something faulty; that Math channel is amazing. Awesome stuff!

Great video We all learn something new everyday

Hard learned job!👏 That would be great if you upload the whole diagnosis chapter of this hard shifting car

Just went down this rabbit hole on a paccar with communication issues, I assumed the wavy waveform had to be the issue. The wave smooths out after about a minute of running, it only happens on start up. Thanks for the video I appreciate it

Hope you feel better Mario

I learned something... thankyou for upload🎉 So i think instead of looking at can high & low waveform, we ahould be looking at the difference betwsen them.

thank you very very much...awesome!!!!

I know I'm late to view this video, but, once again, this young man continues to impress. He should be on the faculty of a technical college.

seguí al ganso por un dia , ahora se porque y como evitarlo gracias Mario por compartir

Just answered a very important question I had.

Thanks for great info. Are you going to show us what it looked like when "hot" and what was causing it?

Hey, learning some the easy way is a learning that will be forgotten. 👍🏼 👍🏼

It's common mode interference. CAN eliminates common mode interference because it is a differential signal. Connecting the scope across CAN high to CAN low. We all learn. Great video. I'm watching because I have a DC offset issue where the DC values of CAN high and CAN low to ground are lower than they should be (out of tolerance). It looks like I'll be unplugging connectors one at a time until I find the module holding the DC low which should result in the DC going back to normal the moment the bad module interface is unplugged. The bad news is that I have a lot of modules! I plan to start with the easiest to access down to the hardest to access last.

I scratched my head when I learned that the CAN system uses two wires. This case is a great example of why they did that, to cancel out confusing noise.

wow i am still impress. good job

very good

You are great

great tip for those of us still using a single scope

Ya ganastes a new viewer 👍

GREAT VIDEO MARIO , I CAN'T WAIT TO TRY THIS DIAGNOSTIC TECHNIQUE OUT . THIS IS WHY WE MUST ALL TUNE IN TO YOUR CHANNEL AND I PERSONALLY WOULD PAY TO SPEND A DAY LEARNING THIS KIND OF OUT THE BOX TRAINING . PLEASE SIR KEEP THESE AMAZING DIAGNOSTIC VIDEOS COMING AND WE WILL DEFINITELY KEEP WATCHING . ALL THE BEST AND THANKS AGAIN ! ! !

Nice !

Great work dude. Noticed you went to chassis ground, I was always told to use signal ground. Wonder if that would make a difference. However great explanation of using math channel and the other way. Yes we have all chased a few geese though.

Brillant Mario, what a great tip, thanks for posting ,cheers sandy

SUBSTANTIAL Super Mario Diagnostics Tutorial great video amazing footage thank you 👍 Take care and have a great day Super Mario Diagnostics From Nick Ayivor from London England UK 🇬🇧

GRAN VIDEO! PERO CUAL FUE EL PROBLEMA DE ESE VEHICULO??

Nice

there is always something that will throw you off and you later on catch it. thanks for the vid

thanks Mario can you show with pico scop you used and with accessory i should bay

hola mario How can I isolate a module that loses intermittent communication

I actually got lucky and learned this by testing known good cars. It definitely looked weird but the vehicle had no issues. When I got another gm I tested again and saw the same thing. So I figured it’s a gm thing. I did notice the waveform looked different key on vs running.

Great video again Mario. Thanks for sharing this. If this Network was in trouble and if there were a lot of codes being thrown, which part/modules would be likely faulty in a car or could it be wiring??

There should be a group similar to "AA" for tunnel-vision! 😉

When doing math, you can decode, to be sure it is compliant. Sometimes not needed, but if you really want to be sure it is talking, and CRC Check, et al, decoding is a must.

Thanks Mario for a great tutorial - Once you have the maths channel, have you tried to run the serial decoding on it? It works well and has helped me in the past to ID the problem controller.

Hi there, was wondering if its a Picoscope thing how you have your signal to trigger off the Throttle body current? - Fairly new to scoping and never heard of this term, as usually I would just crank the vehicle and get a waveform with manufacture labscope.

Awesome tip Mario's we all have been on a wild goose chase and will always sometimes run into it. Was there a power supply circuit open to the t c m?

Also, as far as a strategy, make sure you look at topology. If other modules are communicating on the same buss, that means something. I like to tst at the module, not the OBD, if possible, and there are times the OBD will not have the CAN bus you need to test. Todays carys have a gateway, or diag buss, and you cant get to the CAN from OBD. BTW, Mario, what was the Fix???

Goose chases are fun until the goose starts chasing you.

So there must be some kind of AC component being injected into the CAN bus?