Snap-on Live Training Episode 07 - Data Bus Testing and Diagnosis Part 1

hello everyone welcome thank you for joining our diagnostic training session this evening now if you have any questions throughout the program if you're watching us on zoom just make sure you put them in the q and a box we look in the top or bottom of your screen wherever you see the zoom controls you can click on the little q a button should open another window you can type in your question hit submit and i'll get to them at the end of the program if you're watching us live on youtube you can use the live chat and ask any questions there and i'll be sure to get to those as well at the end if you're watching this on youtube not live the live chat function wouldn't wouldn't be there so um don't worry about that just maybe leave a comment with that um my name is jason cabrinis i am one of snap-on's national diagnostic technical trainers been with the training department the last seven years traveling around north america helping technicians and shop owners get the most out of their diagnostic equipment before that it was a couple years as a diagnostic sales rep with snap-ons so i had 30 different snap-on franchisees i worked with as well as the shops that they serviced in order to help everyone get the most out of their diagnostic needs before that eight years at subaru so i was a dealership technician at subaru and over time became the i guess the default diagnostic guy in the shop right so i was always the one that got the drivability problems the intermittent issues the weird wiring problems that would seem to crop up on those cars always seem to find their way into my bay so that's really where i cut my diagnostic teeth was trying to figure out those strange head scratcher type problems that would come in and before that a bunch of other miscellaneous wrenching jobs been about 25 years under the hood experience for so me topic today is data bus testing and diagnosis and this is actually part one of a two-part course so if you are with us this week this is part one and then next week will be part two so we'll just continue on uh through our discussion next week so for uh this week we're going to do a high level overview of networking and what all network does and and what a network is and we'll talk through uh mainly our low speed networks so it's a j1850 both variable pulse width and pulse width modulated styles uh k-line linbus and can and then next week we'll expand upon that and we'll go into flexray most and talk a little bit about ethernet or diagnostics over ip so for this week focusing on the first three next week as i said we'll expand and go to the next three so a network what is a network let's get down to basics here so network is a system that utilizes information through all available resources so anything on that network in the case of a vehicle all the modules attached to each other are able to communicate with each other now there are some networks out there you might have already heard of you might already know uh such as lan so lan it stands for local area network that is a bunch of computers uh hooked up to basically the same router right so that's like uh in your shop just think about your shop or your house all of the machines all the computers and phones and whatnot all hooked up to that same router that would be a local area network and then we have wan or one which would be wide area network so that is a bunch of lands connected together over a network so that's really just a fancy way of describing the internet right so multiple smaller networks all merged into one larger network and then the types of networks that were talked about in the automotive industry there's more than of course listed on the screen but a few of the more popular ones and of course we know there's a ton of acronyms so we want to talk through that is can so can stands for controller area network lin stands for local interconnect network and then doip which is one of the fairly newer terms that are out there that's diagnostics over ip set as using ethernet protocol like on home computers in order to do diagnosis on a vehicle as well as communicate through networks on a vehicle and when we're talking about a network what it really boils down to is a voltage differential there's a high high level to the voltage and a low level to the voltage the voltage field in between there the difference between the high and the low is what we call our voltage differential different networks work with different voltage differentials at different high levels and different low levels so it's just good to be aware of what kind of signal am i looking for do i need to see a 12 volt signal do i need to see a 5 volt signal do i need to see a 7 volt signal or is it something completely different not just a single volt a single wave square wave so there's just an example right here of a waveform this is a lin bus we'll talk a little bit more about that as we go on but the voltage differential on this lin bus should be around about 12 volts because linbus uses a 12 volt differential so we'll see at the high side here and all it is is just a square wave right it makes different varying lengths of time on a square wave and this represents the different bits and bytes of data that go back and forth between the computer so this one's normally on the high side and then it pulls down the ground in order to communicate and send data so on my high side i'm looking at 13.35 volts so that's whatever alternator voltage was at the time and then it pulls down to 0.91 volts so not even it's almost a volt even so that's 2.44 volts if we do the math in between there take our delta time 2.44 volts in that field there that's within a few tenths of a volt of that 12 volts that's within an expected range of where we'd want to be in this case we wanted pretty much just anywhere over 12 volts and then have a 12 volt range in between if we were seeing maybe 6 7 8 5 volts that would be considered an error on this on this type of network right so we want to worry about that voltage differential we'll compare it between the different types of networks when it comes to testing networks the easiest way to access and probably the most common way to access would be through the data link connector right it's right under the dash easy enough to get to and there are some standardized positions for these network wires so pin one for example low speed can communication so i know gm for uh a lot many of their newer cars they actually have a single wire low speed can and that's almost always on pin one pin two uh j1850 variable pulse width would be a single wire protocol that once again gm used mid 90s through uh the mid 2000s there uh so that's a single wire protocol or that would also be if i had a j1850 pulse width modulated signal positive side that would be on that pin as well and we'll talk through the different networks as we go as i said uh pins four and five on my dlc my 16 pin dlc are always going to be ground so pin 4 is a scan tool power ground pin 5 is a common signal ground so if you need to find a known good ground hopefully you would have no good ground up there but that's a good thing to tap into right there uh pins six and fourteen so that'll be here and here pins six and fourteen opposite of each other that would be a general can bus so the main can bus on a vehicle that's the standardized place for those pins pin seven that we're getting into uh another single wire protocol the k line so keyword communications so that's on pin seven also with the k line we can also have what we call an l line down here on pin 15. so that's used for it's optional it's not always on every car with that but that's used for waking up modules so it'll send a wake-up signal out and wake up the modules pin 16 is always powered and then the other uh pins here denoted in white can be used by a manufacturers at their discretion so for example i know we did a research project on i was like 2013 cadillac and they had their normal can bus here in here six and 14. they also had another can bus on uh lev uh let's see the 12 and 13 and then also on three and 11. so they had three can buses across this vehicle because of the amount of modules on that car they split up the networks into multiple pins on that dlc so really if you want to find a communication problem first off you need to go through a wiring diagram and see where would i find what modules on what wire right so you need to be able to go through that so that is our standardized diagnostic link connector they're using almost every single pin on there at this point it used to just be you know maybe power two grounds and then j1850 so that's what four four pins and now we're using almost all of them so we've come a long way as far as network complexity on the cars right so uh just that's that's why we do these classes right uh good way to get into the diagnostic connector as well it's without damaging anything so we don't want a front probe because that could spread out the terminals that would cause a communication problem perhaps uh we also it's usually pretty hard to back probe there right because usually they're underneath the dash somewhere and pretty hard to get to normally uh so a good way to do that is to use some form of a breakout box this is the blue point brand right there uh it's got a short cable plugs into the dlc on the other side of the box is another dlc where you can hook up your scan tool and then it has 16 of these banana jacks where we can tap in and get a signal so in this case we're just doing power and ground 16 and 4 right but if i wanted to do can i could do 6 and 14 right and they could just tap in there and you can also communicate with the vehicle at the same time as you're reading that signal and oftentimes you won't get a signal until the vehicle starts communicating it'll often just sit there at idle and not transmit any data until you call for data from the vehicle so what i like to do when i don't see communication on there is i'll just go into a data pit list and just have it send data to the scan tool that way we can see the back and forth between the module and the and the scan tool so let's talk about low speed networks start at the start of the bottom i guess work our way up and in speed right so start with j1850 that's a fairly common one like i said back mid 90s through mid 2000s gm was big fan of this uh they use that on very many of their vehicles j1850 vpw which stands for variable pulse width so it varies the pulse width in order to transmit the signals that bus consists of a single wire with a transmission rate of 10.417 kilobits per second if you need to know down to the hundredth of the of the kilobit right uh it uses a seven volt differential so what we should see when everything's communicating correctly is a seven volt square wave going across the screen uh j1850 pulse width modulated bus is a two-wire version of that so it's actually a higher speed transmission or higher transmission rate 41.6 kilobits per second so considerably faster but four times faster uh than what the single wire is this was pretty common on fords of the same air so roundabout obd2 through you know mid 2000's when they went to can so in this case they use about a 5 volt differential on my data so here's an example on a variable pulse width so that is a single wire gm class 2 data bus they call it so that's on pin two on my dlc there and we see it's just a seven volt roughly square wave right there and then here's an example on j1850 pulse width modulated off of ford you'll notice that there's two channels because i said we had a positive and a negative right and then it's about an every other data bit goes up and down either higher or lower than the others and they pretty much mirror each other on both sides you see you have a larger packet there a smaller packet there in this case on the smaller packet pin uh high sides going to 4.5 low sides going a 0.55 so that's about about 4 volts in there and then on this one with the bigger bigger packet there that's 0.22 to 5.04 so that's almost five volts there right so there's your difference in between uh the different data packets you can see how a known good would look in that case then other vehicles uh round about that same era we'd use k line so k line is uh just on a different pin and it's another single wire boss and it transmits at a rate of 10.65 kilobits per second so it's a little bit faster than the j1850 but it's still fairly slow in the grand scheme of things uh k-line uses a 10 to 12 volt differential i've seen some with 10 volts some with 12 volts and i'll tell you what on subarus since i have experience with subarus right subaru used k-line all the way up to like 2014 for their scan tool so if you've ever noticed maybe data collection on some subarus might not be as fast as you like that's why because they use that k line protocol which is slower than any of the other protocols they could be using such as can so there's about 10 volts there on the top and there's about zero volts there on the bottom so there's my data data packet right there so my high side my low side there's my different bits and bytes of data as we go now let's talk about linbus so linbus is newer i guess you could say on the scene lin stands for local interconnect network and it was specially developed to achieve cost-effective communications for intelligent sensors and actuators in motor vehicles it requires a master controller and a slave controller so we have one telling something else some what to do so usually like a switch and a motor or something of that nature it's used wherever the bandwidth and versatility of can are not needed so can is a considerably more higher speed uh it has more bandwidth that's able to transmit more data with lin we don't need to transmit that much data on there it's more of an on or off type situation uh with can it's sending speed sensors and temperature sensors and all that information around the modules on the vehicles so lin is really used for a lot of like your body type communication so it's once again it's a single wire and it has a transmission rate of up to 20 kilobits per second so once again we don't need to drive the car with a lin bus uh we need to turn things on and off with a lin bus so that's why it doesn't need to be that fast it just needs to be fast enough for a human being to notice uh when it happens right so lynn uses a 12 volt differential as we had mentioned earlier on when we saw that first slide there so things that we would use lin on uh roof sunroof controls lighting controls steering wheel pretty much most vehicles nowadays anything any of the button on the steering wheel can be a lot of buttons on a steering wheel now those are often lin uh seat motors occupant sensors control panels for the seats engines sensors and small motors just the the inconsequential stuff that not really the throttle or anything of that nature but you know smaller things grill shutters you know active grill shutters are pretty common nowadays uh climate control my blend door actuators etc how about doors mirrors mirror switches window lift motors how about wipers now if you were if you were with us last week and we talked about uh that there was a 2016 tahoe for the body control module for the rear wiper well that control for a rear wiper on that vehicle from the module to the motor is just one lin wire the lin sends the signal out and it says okay turn on alright so that is that that is a type of lin bus that we would use so as i said many body electrical things is the majority of those and then here's just another example of that lin bus signal a high side of 13 volts low side and nine tenths of a volt we have about a 12 volt differential in there and that is uh that's close enough right so that is all of our single wire networks we're going to talk about now let's just scratch the surface or get started with our two wire networks so we'll start with can because once we learn can we can apply it to most of the other two iron networks because they're very similar in how they operate so high speed can consists of two twisted wires with a transmission rate of around 100 to 500 kilobits per second that's a pretty good swing there so when you get down in maybe the 100 range you'd be thinking maybe you could call that mid speed can because you may have heard of that before and then higher speed cans 500 kilobits when we get up faster than that we're talking about maybe some other different technologies such as flexor which we're going to talk about next week uh so can uses about a two to a two and a half volt differential as we look at the way the picture looks the data packets uh we'll see where we get that two to two and a half volt differential one signal circuit is called can high and the other one is called can low so we actually have two as we said twisted wires and by the way it is important to keep those wires twisted if you ever have a problem and you're taking things apart and testing things you want to leave those wires twisted up because that's good for rejecting rf noise right that's why they're twisted together to reject the noise now each end of the data bus there's a 120 ohm resistor at the end of any line on the on the can bus so i know i've seen vehicles where they have just like an open spot for an optional controller that's not equipped on this vehicle and they just plug in a little resistor wire in there just to keep tell it here's the end of the line we don't need to have any more data past that point it's basically what that 120 ohm resistor does for us so here's a simplified graphic of a can bus so if can high as we said that terminates on dlc pin six and then dlc pin 14 terminates with can low more often than not that 120 ohm resistor we talked about across the end of the wires that'll be inside a controller and more often than not if you have a can problem more often than not it's a controller the thing about can is it is a mesh network so everything is connected to everything else it's also fairly modular so we can expand as we go so we can add a few modules on there and they'll start communicating transmitting data back and forth you want to add some more modules sure let's add some more modules just plug in a couple more as i said we could have those optional optional plugs right and then even if we have a single module on there it can still use that can protocol to talk to the scan tool right so we can actually get data out of a lone single module on a can bus network so it all works uh you know it's it's fairly i don't want i don't want to say it's very that complex but it is definitely more complex than that than the single wire networks we were talking about before and the messages are different and the patterns are different but if you know how to diagnose this it'll help you diagnose any of the other two wire uh modules uh so here's an example high speed can known good here and we'll and we'll talk a little bit more in depth about the voltages and what we see here in a few minutes when we go live on the tool but we want to see a flat line here which is our idle voltage and then these data packets are the uh the square square waves here and what you're actually seeing and on this two wire is you're seeing a round trip so this side goes out this side comes in right so it's kind of like a transmit and receive and then all the modules have clocks inside them like crystal clocks and they can they can change the timing of those packets so they line up right so we want to make sure they line up we want to make sure they're even on either side and as i said we'll talk about that a little further uh in a couple of minutes and that's on pin 6 and 14 on for the main network on the dlc we have these various networks on a vehicle how do are they able to communicate with each other can they communicate with each other well in order to do that yes we can so we would use what we call a gateway module to translate the data from say a high speed network to a low speed single wire network on a vehicle if we needed to have that happen think about it like a router right so you have your wi-fi router at your shop or at your house and it routes the signals wherever it particularly needs to go right so i could i could have hardline it could have wi-fi and out in the out in the shop right so it just routes the signals oftentimes on a car it could be called a gateway module often times on a car it might not be called a gateway module could be in some other sort of module on the vehicle i think of like signal acquisition module on a mercedes that works often in that type of way body control module oftentimes can be your gateway module as well to translate those signals between all of them let's use just a sample scenario for example so i have a little wiring diagram here and let's say on this vehicle this is a chevy i think it was a malibu um we have a technician that can't communicate with the vehicle so they go in and scan they try to scan the engine for codes and they can't communicate with the engine module so they suspect that there's a problem with the scan tool well oftentimes more often than not it's probably not the scan tools fault it's probably the car's fault right so if you think about it why is the car in the shop in the first place it's probably because of the problem right so if you ever run into that situation we're trying to scan one module at a time the best way to avoid that is to maybe do that pre-scan on the vehicle or rescan all the modules and see what we have for communication but that's also a good way to check for communication because if say i didn't have communication with the engine the transmission the body control module the brake module etc but i did have communication with say like the radio and the srs module and you know maybe the instrument cluster i could communicate with half the car and not the other half of the car that's where you might suspect a gateway module is the problem so if we look at this wiring diagram i have on the screen on the left hand side that is the dlc all right we got pin 16's power pin four and five are ground looks like on this one it also has cans so that's pin six and fourteen as we said before and for those pins six and fourteen they go right into the body control module and then pin one is their low speed single wire network and that also goes into the body control module all right so all signals go to the body control module before it goes out to the rest of the vehicle so that means that is my gateway module and we see we have just the two wires on the can go out to the high speed portion of the car well maybe it's not translating and maybe there's some sort of an error on this part of the computer because i can communicate with the rest of the vehicle on these green boxes i just can't communicate with anything in this high speed area right so that would be the body control module so in this case it was the body control module they uh replaced it and communication was restored with the vehicle with all modules so it's just the body control module is not letting the signal pass for the high speed side so speaking of errors and problems what kind of problems can we have and what would that look like because you can't always get a known bad pattern right but in this case we do have at least one known bad pattern so this is on a single bus or a single wire bus j 1850 bus and we can see it's 7 volts on the top and as we learned earlier this should be a square wave right we should have a flat top and a flat bottom but we don't we also have seven volts here and then it pulls down to ground in order to send a signal so ground is here that's zero volts notice how the bottom is not always making it to ground over here it did over here made it down to ground but it took a long time to get there if you ever see a pattern on a scope and you want it it's supposed to be a square wave like coming down nice and straight and then over and you see it curve like this instead on the leading edge that indicates high resistance on the ground side so it's not pulling it down to ground fast enough so we think about what a scope is it's basically just a voltage over a time right or a signal over a time so if i am coming straight down that is a very short amount of time to get from seven volts to zero if i'm coming down in a curve like that though that means it's taking a long time because horizontal is the time so the horizontal measurement is the time so if it came down nice and straight that's very fast that's a short amount of time this is taking a long amount of time to get down the ground over here it didn't even make it the ground it was like 0.69 volts all right so it didn't even make it the ground over there so that is an indicator of a problem on the ground side of the circuit so how would we test this vehicle well first off we take out the uh we would have maybe a communication issue first off second off we would probably go and pull a wiring diagram be a good thing to do so we have a wiring diagram here on this vehicle it was a gmc truck and on this vehicle we used a single wire protocol off pin two there and also on this vehicle and it's not just gems many vehicles have this style of network they call it a start style of network so each module has a single wire that goes to a central point in this case they call it a splice pack or gm might also call it a star connector so that is where all the modules will link up in this one connector and then there's a shorting bar that goes in there that shorts all the modules together so they can communicate and then it goes over to the dlc as well if any of these modules go down it could pull other modules down as well or maybe a group of modules if we have a problem say over there right so we can go through and we can test that and see by disconnecting modules this gives us a test point under the dash so there's just an example of what the connector would look like there's that shorting bar right there all you do is pop this out it's attached to one of the main harnesses on the vehicle and it's just straight across as 12 pins now what we could do is we could do jumper wires uh if you've worked worked through the flow chart on one of these cars it says use jumper wires or uh paperclips that sort of thing um to check for communication between the modules so you put put one wire where the dlc comes in and then you'll go to the ecm then you go to the tcm etc etc etc and see how the network performs we also have an automated tool that can do that for us as well now it's designed to work with gm's it has the two main gm connectors that come with it but it also has a universal connector that comes with 12 pins uh that can connect and many other manufacturer vehicles many vehicles have this style on there and what it does it's called the data bus fault finder now i also hear these might be getting a little hard to find out there but if you do have one or if you were able to get one um it plugs in to that same cable there it scans the whole bus and checks do i have connectivity to the module and is that module shorted to power or ground so in this case we have these pins here need to be on the right screen there and back up all right so we have these these lights which indicate i'm that it's connected to the module and then we have this one shorter to ground or that one short of power so this module's the ground that module's the ground that modules the ground and the bus overall is also shorted to ground takes like 10 seconds to figure this out then we also have these buttons on here and these buttons will take that module out of the circuit and see if the pattern changes so if i take a module out of the circuit pattern gets back to normal then i know that module is connected to whatever pin that is d or f or or uh h whatever it happens to be that's the problem right so you just go one at a time turn it off does it get better turn it back on turn it off doesn't get better until it does now you could also do that manually if you didn't have access to one of these tools you could do it manually just by find the module under the dash unplug the network connector see if the pattern resolves itself if it does then you know that's your bad module if it doesn't then you move on to the next one you can also use that uh splice pack underneath the check if it's set up in that way so we would go through and then here is a normal look for a you know single wire bus you know we have a square wave nice and square it's not having those strange ground side problems that we were having before we don't have the curves we have it kind of nice and straight down so that's an example of a fixed car all right so that is our overview for tonight we're going to go into live on the tool now i'm just going to look through chat here real quick looks like youtube chat looks clear and matt is asking me a very long question so i will get back to you at the end so we'll take time now we'll that's that's a good paragraph there about so we'll i'll get back to the question at the end all right so uh here is my zeus and the best way to find information on networks on any of our tools that have guided component testing uh so be anything with the scope because you do need to use a scope to test the network as you can see with those pictures on the screen you really can't test it with a meter it won't really give you any information as to what's going on so you do need to go in any of the tools of the guided component test so zeus varus modis triton and vantage all right any of those tools we'll have the guided component test we click on that once we load in there we have this little secret that's been in here for a while but we have built in training and classes on scope use guided component testing use etc so we go in here and i go into the how-to section there are 65 different categories of class 10-minute classes 15-minute classes 20-minute classes under each category there's generally at least two or three or more classes so let's say for example well i i went to that class the other night and i learned about that lin bus stuff but i didn't quite remember all of it so right here 10 minute lin bus class you can walk through here and it tells you all about lin bus and how it works and how we have a a 12 volt here and we have a zero volt there and we should see a square wave like that recessive and dominance when it's transmitting or not and if we come down here it gives me a known good pattern and if we come down a little further we even could connect to the vehicle and then click view meter and it'll turn the meter on set the voltage where it needs to be sets the time where it needs to be and then that gives us uh you know the information very easily uh in that case so that's land bus if we go down a little further down i think the 20 minute classes we have can bus there are multiple can bus classes if you wanted to go basics and fundamentals bus arbitration if you care about learning about that uh can voltages error handling signal quality how about waveforms waveforms is actually a known good and bad waveform library in here for can for generalized can overall so we see here we have this a good one this one's with the low signal open this one's with the high signal open this one's with the low side shorter and positive shorted the power could also be look like this depending on where we are on the circuit there's high side shorted to power and then we have low signal uh short to ground could be shorted to ground here because the high side can still communicate if the low side shorts the ground and vice versa uh so we might see a little bit different activity there let's see can high signal short to ground and so on and so forth oh and here's where they're shorted together they are actually look identical to each other they both use the same so these are shorted together by themselves so you come down here once again hook up to where it says so pin six pin 14 black to ground and actually have this hooked up to a can bus so we can see what that looks like and there's my signal on the screen so you can see that it uh that it automatically sets the voltage to 5 volts because we know the range should be within that 5 volt range and then it also sets up our time to about 200 micro seconds i can slide this over here if i would like to make it a little easier to see and there is my can bus signaling on this vehicle it's a bmw simulation now you may notice something a little bit different about this particular pattern versus what we've been looking at for can before so we have this extra large bit over on the end here and some vehicles not all canned vehicles but some canned vehicles you will see this this is what they call an act bit or an acknowledgement bit so that's basically telling other computers on the network okay here's all my data and that's where the data ends this is the period at the end of my sentence right so i'm done here and then whatever comes next it's another module right so this is acknowledge that it's sent and acknowledge that it received so that's my acknowledgment bit right there so you may see that depending on the vehicle all right so that is learning a little bit more about networking there's multiple other classes in here you know uh battery drain dynamic steering etc etc so you can really just go through there and and see there's a wealth of knowledge in here also if you wanted to just do a generalized can bus test so to stay we could go into power user tests as well for a dual channel test there's one on can there's one on flex-ray as well which we'll talk about next week we go into can bus same thing this one actually looks like it's off of that bmw and then we would see that same type of pattern now it's generalized vehicles if you're not really sure but another way we could do it since we have the information in here already there's over five million guided component tests in here and some of them are for networking uh so it's vin specific goes back to 1981 covers 28 different makes so in this case i have a bmw demo board so i'll go into bmw it's 2012 328i with an n52kp go in here once i've loaded a vehicle it'll give me a list of systems in this case can bus would be considered under the engine system because that's my main network and then we have can bus here so we can go into component information and take a look there's a wealth of information in there i'm not going to read through all of this uh but you're more than welcome to because you can hook up that you can identify any car and you don't have to hook up to it in order to read this information which is also a nice thing uh looks like in this case it's also good to go to a the ecm sometimes uh so the can low can hide tells you the wire colors tells you where they are assigned as far as pins go or we could check it at the dlc as well if i back up there and i go into my signature test you see it tells me where to connect my wires yellow black and green and then it gives me my pin assignments there signature test gives me a known good pattern on the screen and then we can also look at the waveform information which we're going to talk about right now so open the meter and see it does give me a little bit different look it's a little bit wider of a look so 500 microseconds that's 500 millionths of a second in width my height is still set at 5 volts though so we pull that down a little bit all right so i'm going to change this get in a little bit closer so we'll change the time down a little bit go in here get the time a little bit closer so we can investigate a little closer could go to 200 could go to 100 as well 100 wouldn't fit the whole set of data on the screen but that's okay but we'll just leave it like that all right i like putting them on top of each other so they're close okay so let's turn on my cursors and see what we get for information we have for voltages so when it comes to can okay i didn't click that click that by accident all right so when it comes to can there are set voltages that we're going to use in order to uh verify whether or not the network's working properly so you see we have two states we have our recessive or idle state and then we have our dominant dominant or transmitting state so we have either it's not transmitting data or it is transmitting data as we said before these squares are the data packets so can high we have canon low when you're connected to a vehicle and it has can if it was known good uh we have two and a half volts in the idle state so any of these flat spots in between the data bits should also be this level uh so we should see around about two and a half volts so in this case two point three six nine two point three seven three then when it transmits data the high side goes up anywhere from a volt to a volt in the quarter is normal expected range so if i see a volt that's good if i see a 1.10 we're good if i see a volt in the quarter we're good i should go down on the low side by the same amount so it looks like we have goes up to 3.275 down to 1.404 difference between those is 0.906 and 0.969 that is pretty darn close all right it's really close to a volt on both sides that's within the margin error so we're good there we want to see nice flat tops we want to see nice flat bottoms if we have zero volts at any time looking at can with the key on uh we don't want to ever see zero volts that's a short to ground we could see one line stuck at ground we could see just a quick little glitch that just drops down to ground that's a possibility as well uh that would indicate that line is shorting the ground and it could just be one module that's doing that as well i don't want to see any noise if i saw say maybe it looked like a lot of static a lot of ups and downs and maybe looked like an audio wave if you're seeing that where it goes up and down a lot uh that would indicate high rf noise in the pattern and that would be a bad thing too so that can cause interference in between we can't always necessarily get that signal right at the dlc off it's the best place to test but oftentimes it could be also internally in the network in the car too so where would i need to go for that so a good example of where we might go for that is our shop information right so if you have a varus or zeus or one of the windows based tools i don't know what my password is no but that's okay um it will load the vehicle it'll load me into my information system if i have shopkeeper or mitchell pro demand it will load me in there it will give me my options and i can look at the vehicle and where i like to go for my wiring diagrams is we could look up the computer we could look up can but if we go into wiring diagrams and we pull up our computer data lines because all of the wiring diagram categories are identical so we'll go to computer data lines then we'll pull up my computer data line circuit so it looks like there's two pages for this so i can just click on here and it will pull up my circuit so we can see here's the data link connector over there let me zoom in a smidge all right so that's my obd2 socket as they call it so it looks like pin three and eleven that's one circuit we got eight and that must be eight and twelve right and then we got uh fourteen and and six right so fourteen and six mean can so k fourteen and six go in the disjunction box onto the right side of the dash from this junction box it goes in and then it would translate all of the different signals so this is basically our gateway here we translate the signals to the other parts of the vehicle looks like we have a couple loops in here so 0 is probably those 120 ohm resistors on the ends of open lines for the network could also check and see whoa what about this junction box so it's highlighted there in blue so i can just click on that from the wiring diagram and it should do oh i got to give it some extra information here i guess so i'll call it a coupe okay there we go it wants to know whether it's a coop or not okay there we go that's better so there we go okay so are there tsb's related to this junction box what are my top repairs causes and fixes specifications how about my location where's that so i can click on component location right from the wiring diagram and then it pulls up any of my electronics for that junction box all right so i could pull that up right from here and it gives me all that information right from the wiring diagram right so being able to check through a wiring diagram to see how is this vehicle wired because if i had a communication problem here we see everything goes in there first so i'd want to check in this junction box first and then i can also a testing point for any of my other modules on the vehicle so that just makes it a little easier to test all right so that is our week one of networking let's go and talk about week two of networking so next week we'll be continuing this discussion and we'll be sticking to the two-wire network so we'll start do a little recap on can and then we'll go through flexray which is pretty much just an advanced version of can we'll go with most which is a media oriented systems transports actually what that stands for so that's media involved and then talk a bit about ethernet which is a emerging technology in the last four or five years there on some vehicles uh so we'll talk about that as well so next week same time same place uh six and eight pm eastern on tuesday wednesday 1 pm eastern and then on as we're doing right now our session two on tuesdays gets live stream to you to you as well when the live stream is over that video is always available to watch anytime in the future uh so if you are watching us on youtube and you like the content please make sure you thumbs up subscribe ring the bell in order to get notifications for the next time we go live with that let me get to questions and while i'm taking questions let me look at this so this is uh this website that we have up here on the screen this is your one stop shop for any of our live online training that we've been doing so including these classes are available you can register there also we have what we're calling our new customer onboarding type classes so these are everything from setting up your wi-fi how about setting up your free snap-on cloud account in order to share uh vehicle reports and screenshots etc all the way through a standard diagnostic workflow procedure everything from scanning the codes through you know how we verify that our fix is there so it walks through all aspects of the tool uh mondays we talk about the apollo d9 my friend al mccaskey hosts these class so mondays apollod9 wednesdays are zeus and thursdays are triton d8 also on the zeus and the triton d8 days al talks through a bit of guided component testing as well at a high level so the apollo class is about an hour and the zeus and triton class are about an hour and 45 minutes give or take because those have the extra guided component test aspect to them uh so with that i don't see anything in the live chat on youtube so let me look up uh in q a and this is going to take me a second to read here okay so that seems more like a comment from that than a question but uh on a 2015 mitsubishi outlander get into the body control modules and be able to change headlights change coming on lots of different setting changes available inside the zeus yeah so thanks for that comment definitely there's there is so much subject matter that i could talk about on any of these tools especially with how these cars are nowadays and programming and changing settings in there and coding and all that i think actually might we might we might do a class on programming and coding and the differences and such as that but definitely thanks for that feedback thanks for that input matt and i know i appreciate you attending all these classes i see in here every week so definitely appreciate that as well uh so thanks for that with that i do not see any additional questions in here i'm gonna give you another minute or so just to type them in if you do have them i'll just give you a little bit of time because i know i'm not the fastest typer in the world either so i'll give you a little bit and uh definitely make sure you check out our website snapon.comt and also if you're on youtube like subscribe hit the bell all right with that i guess that is it so appreciate all attending everyone have a wonderful rest of your week however much you have left and uh for those veterans with us tomorrow's veterans day so definitely appreciate your service and uh thank you for looking out for our country right so with that

Channel: Snap-on Diagnostics

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Length: 44min 36sec (2676 seconds)

Published: Wed Nov 11 2020