00:00hey welcome to can bus communication now
00:03I've been contemplating this class for
00:05quite a while now but that's because I
00:07wanted to get it right I wanted to focus
00:09on a class where you could take a car
00:11with a communication issue and go
00:13through the entire process of getting it
00:16there's a lot of really good canned
00:18stuff out there but what I feel it lacks
00:21or what I really never liked about a lot
00:22of it is so much of it focuses on the
00:25protocol itself the ones and zeros the
00:29binary code or it focuses on the testing
00:32right away like what is a good lab
00:34pattern look like and I don't feel like
00:37that's the steps that we take when we're
00:39actually diagnosing these things so what
00:42I did was I took notes on what I did
00:44when I was diagnosing these in the
00:46actual shop in a real world scenario and
00:48I built a class around that and this is
00:53so here are the four topics that I'm
00:55going to cover and these topics are
00:57topics are also in order of process we
01:00have one two three and four
01:03and you can see that Network and
01:05troubleshooting is all the way down
01:06there on the bottom and it's down there
01:08for a reason not just because I think
01:10the other three are just as important or
01:14more important than the actual testing
01:16but a lot of times when we're when we're
01:19fixing these things or looking at these
01:21things will actually get to a solution
01:22before we even get out the lab scope or
01:24even get out the multimeter to test
01:28starting with communication networks
01:30we're going to talk about the ginormous
01:33networks that we're dealing with today
01:34and how to break them down into more
01:37manageable chunks something that we can
01:39actually diagnose we're also going to
01:41talk about why we break them up and how
01:45then we're going to talk about Network
01:47topology and this is the wiring layout
01:50of the network and this is also really
01:53important because even if we're just
01:55talking about can bus there's numerous
01:57ways these things can be wired and if
02:00you don't know how something's wired
02:02then yeah it's kind of hard to test with
02:04any piece of equipment
02:06then we're going to talk about the
02:07protocols and languages and when I say
02:10protocols I mean protocols with an S
02:12because can bus has more than one
02:14protocol and there's a lot of other
02:16protocols or languages talking around
02:18can bus on the network and we need to
02:20understand all of them and or at least
02:23how to identify them in order to be
02:25successful when we're diagnosing canvas
02:27issues and once we get those three
02:29covered then we're going to talk about
02:30the actual Network testing and the
02:32troubleshooting and this is a lot of
02:35information I know that so what I did
02:37was I decided to break it up into a
02:40and for today I'm just going to cover
02:42communication networks and why I'm
02:45starting with communication networks
02:47well I think this picture Explains It
02:50this is what a modern day Network looks
02:53like and this is a 2021 Cadillac
02:55Escalade and it's a lot to look at and
02:58if I'm being honest it's only two-thirds
03:00of the actual Network I couldn't even
03:02fit the whole thing on here I tried but
03:05it was so small it you couldn't even
03:07pick anything out and you can kind of
03:09see already why we can't just get all
03:11our equipment and start testing because
03:13it's more about where to test where are
03:16we testing then what to test on these
03:17new networks and a good way to explain
03:21that is let's think of this as like a
03:22road map you have your roadmap and you
03:25could be the best driver in the world
03:27but if you don't know where you're going
03:29you're just going to end up driving
03:30around in circles until you either one
03:32run out of gas or energy or you just get
03:35lost and quit and that's what we're
03:38finding with a lot of people trying to
03:39diagnose these networks these days
03:41they understand the protocol or they
03:44understand how to use a lab scope or how
03:46to use a Multimeter but they just don't
03:48know where to start so that's why we're
03:50starting with communication networks and
03:53what we're going to do is we're going to
03:54break them down and the easiest way to
03:56break them down is let's start from
03:58beginning and build one up from where
04:00they started and how they're constructed
04:02because if you know how something's
04:03constructed that makes it so much easier
04:06to deconstruct it essentially so let's
04:09start with what did we have before we
04:11had networks well we had stuff like this
04:14now this could be your dad's old IROC or
04:17it could be an old Ford truck it really
04:19doesn't matter but what we had was a lot
04:21of redundancies so this is a picture of
04:24coolant temp sensor and the engine
04:26control module needed it so it could
04:31well the engine or the instrument panel
04:34cluster also needed the engine coolant
04:37temperature sensor so it could display
04:39it on the dash and this worked fine I
04:42mean sometimes we replace the wrong
04:44sensor sometimes we diagnose the wrong
04:47butt ass cars got a little bit newer
04:49then we started getting evap systems now
04:52the engine control module needs the fuel
04:54level sensor well obviously the gauge
04:57needs it because we don't want to run
04:59and we got VVT systems so now the engine
05:02control module needs the uh oil pressure
05:05sender and then we have that on the dash
05:07so we started getting to the point where
05:10we needed modules to have some type of
05:12ability to communicate or share
05:14information and we also got to the point
05:16in technology or advancements where they
05:18could do that so this is a solution
05:22you can see in this picture now we have
05:24our coolant temp sensor and it's sending
05:27its signal to the engine control module
05:28but instead of having another coolant
05:31temp sensor now we're just sharing
05:33information we're sharing information on
05:35the network because that's what we just
05:37created this is a simple network two
05:39modules sharing information
05:43I was just a simple Network it's just
05:45modules talking to each other sharing
05:48data and it doesn't have to be four
05:49modules it could be three modules it
05:52could be two modules but this is a
05:54network in its simplest form
05:57nowadays they don't just share
05:58information they also work together to
06:03so some of the earliest systems I can
06:05remember is the ABS module teaming up
06:07with the powertrain control module and
06:10it created traction control systems so
06:13now when you're in that parking lot
06:14you're you're doing donuts and making a
06:16big smoke cloud the ABS modules tells
06:19the PCM hey tires are spinning so the
06:21PCM takes away your throttle and you got
06:23to find the button to turn it off I'm
06:25just kidding but then we have our old
06:28radar systems that were just the beep
06:30beep beep now they're working with the
06:31big screen TVs and the cameras and now
06:33they're creating park assist
06:35and this wasn't too bad I mean it makes
06:38sense and it doesn't really change how
06:40we diagnose we just have to understand
06:41how they work together and it gets even
06:44a little more complicated than it is now
06:46we have all four of those modules
06:49and they created one of the first
06:51systems so now we have our our radar
06:54module here and it sees a pedestrian
06:58and before all it would do is tell the
07:00driver hey bbbb you're gonna hit
07:02something but now on cars it tells the
07:05ABS module to pump the brakes
07:07and it stops the car for you and if your
07:10brakes aren't strong enough because your
07:12engine's too strong then it will talk to
07:13the engine control module and it'll take
07:17and it all it is is four separate
07:20systems talking to each other working
07:22together and this is what a
07:23communication network is at least this
07:25is what it looks like when I draw it
07:27with pictures but what we're normally
07:29going to be looking at is we're going to
07:31be looking at wiring diagrams and this
07:32is what we have to break down so let's
07:34look at it from the earliest wiring
07:36diagrams now this is beautiful
07:39this is what I started looking at when I
07:41first started working on cars simple
07:42networks like this and we had our DLC
07:45here but you know it may have actually
07:47been an aldl for those of you who
07:50diagnostic port but it was just simple
07:53one-wire networks and some of these
07:55still exist but this was the whole
07:57network it was the PCM talking to maybe
08:00one or two other modules and abs was you
08:03know if you had the option you had ABS
08:05that was actually an option back then
08:06and it was just one wire so there's
08:09really nothing to break down here so we
08:11didn't really worry about it too much
08:13but that didn't last too long did it we
08:16very very quickly we got into stuff like
08:19and this is a more modern Network that
08:22we have today not the most modern
08:24network but this is just a simple
08:26picture of what it might look like and
08:28now you can see you have three separate
08:30networks within one big Network and the
08:33thing about all these networks is not
08:35only are they all communicating at
08:37different speeds and different voltages
08:39and things like that they're also all
08:41still communicating together and now we
08:42have things like Gateway modules now if
08:46you think about it like languages let's
08:48say this red network is speaking one
08:51language this yet green network is
08:53speaking some language and this blue
08:55network is speaking some language well
08:57the Gateway module is The Interpreter
08:59that lets all these languages talk to
09:01each other so that it creates one big
09:05so essentially now this is broken down
09:08from a big Network to three smaller
09:10networks so this is how we have to
09:12diagnose it and it gets even more
09:14complicated and that when you look at it
09:19this is can bus communication does this
09:21really matter well when you're looking
09:23at this this one right here well this is
09:29and guess what this is can bus too
09:32so now when we're diagnosing canned
09:34we're not just diagnosing one can
09:36anymore so we have to know which can
09:38we're diagnosing what network do we have
09:40to find and this you know this could be
09:42a low speed can and all three of these
09:44networks might speak at different
09:45voltages in different languages and
09:47different speeds but before we get that
09:49far we have to figure out what network
09:52and what else do you notice about this
09:55let me get my uh John Madden stuff out
10:01it's not connected to any networks
10:03anymore it's connected right to that
10:06so if we test from the DLC are we going
10:08to test any of these networks anymore
10:12if we take our multimeter and we do our
10:15old uh true test of powering down the
10:18network that's what we always do on can
10:19right we'd power down the network we
10:21take our multimeter on Resistance and we
10:24would go to the DLC we measure at 6 and
10:2614 and we'd look for 60 ohms
10:28can we do this anymore
10:31no we can't can we get our scope out and
10:34look for a pattern here anymore
10:35no because we're only going to the
10:38Gateway module so what's the first step
10:40we have to do we have to break this
10:42thing down what network are we looking
10:43at this can Network this scan Network or
10:46maybe this low speed can Network then we
10:48have to find out where do we diagnose it
10:50where do we tap into it where can we
10:52actually get a reading to test it and
10:55that's exactly what I'm trying to
10:56explain in this class today and this is
11:01this is what we're looking at now
11:04I mean that's crazy I I tried to count I
11:07believe there's 80 modules on here and
11:09remember there's only two thirds of it
11:10so there might be a hundred modules on
11:12this car but we can't let that
11:15this is the first step to winning and
11:18the first step of failing I guess I
11:19would say so when you get a
11:21communication issue we need to break it
11:23down and there's a lot of different ways
11:24to do that and one of the easiest ways
11:26to do that is just like this
11:28a lot of the service information has the
11:30data networks like this so now it's
11:32already broken down in different figures
11:34different sections but it's still a lot
11:36to look at and it goes again why we
11:39can't just go right at can look at this
11:40look at all these cans one can one can
11:42two can three five eight powertrain info
11:46you'll go nuts trying to look at this
11:50so we have to break it down we have to
11:52look at the network in sections to be
11:54successful and let's look at a case
11:56study we'll break one down and it'll
12:00so this is a 2021 Cadillac Escalade
12:03hence why pick that initial diagram and
12:06quick backstory on this is it was at
12:08another shop and it was the fuel pump
12:12driver modules are placed I mean Chevy's
12:13never had any problem with fuel pump
12:17and there's still no communication the
12:19technician that looked at it is a
12:21technician that has some can experience
12:24but not new can experience and he said
12:26the scope pattern looked good
12:28from the DLC and there's kind of a weird
12:32resistance reading but all the other
12:33modules communicate so he there's there
12:35can't be anything wrong with the network
12:36right so we look at the car and it has a
12:41u18a2 yeah there's numbers and dtcs now
12:43too that's always fun so here's the code
12:46it has and we confirmed there's no
12:49communication with the fuel pump control
12:51module so where do we start well let's
12:54start by looking at a wiring diagram
12:55because that's where we always start
12:57and luckily this wiring diagram is
12:59interactive the the one I'm showing you
13:01is a little easier than you may have to
13:03go through but it's really good for
13:05learning so this is why we're using this
13:07one but the first thing we do is we
13:10check to make sure there's power and
13:12I mean that's the first thing you're
13:13going to do when you're diagnosing these
13:15networks but you got to check to make
13:16sure it's power on ground and there is
13:18so what do we do we have no
13:20communication let's look at the network
13:22let's break it down so what do we find
13:24the communication lines right here and
13:25it says data Community data
13:27communication schematics and if I click
13:29on that it brings me right here
13:34that's only one that's not bad right and
13:37remember I said it's not always going to
13:38be this easy sometimes you have to look
13:40at each one to try to find where they're
13:42but we still need to break them down
13:44now look what we had before
13:47we had 24 cans or 24 so now we can cross
13:52and we only need to look here
13:54we're already making this big thing
13:56we're making it smaller because this is
13:58the only thing we need to look at
13:59because this is where this module is
14:04we get nothing out of that
14:08and depending on manufacture or I should
14:11say depending on option codes so this
14:13thing is showing some diesel options and
14:15you can see these RPO codes here this
14:17car doesn't have diesel
14:18cool so now we can get rid of this let
14:21me get rid of this and get rid of this
14:23and see we're not testing anything yet
14:25we're just looking at the wiring
14:26diagrams or finding the one section we
14:28have to test we're not worried about
14:29what's at the DLC we're not worried
14:30about what our lab scope says yet so we
14:33get rid of the diesel stuff and now we
14:36now this is beautiful
14:38this isn't look intimidating at all and
14:40this isn't and it shouldn't be but what
14:44what are we used to seeing when we
14:47well I'll tell you what we're used to
14:54I mean this is what we're used to
14:55dealing with can this is what we're used
14:57to diagnosing and this is how a lot of
14:58the classes kind of depicted still and
15:01it's just not going to get you anywhere
15:03we used to have the the DLC here and 6
15:06and 14 went right to the high-speed can
15:07bus so we'd go there and we test
15:11this is what the DLC looks like on this
15:17are we going to get anything
15:18all of these wires are going to a Serial
15:20Gateway module every single wire at the
15:24so if we test the canned circuit on our
15:27lab scope we might get a good signal
15:31and if we do a resistance measurement
15:33for our resistors look at there's little
15:37so maybe we'll get a good signal
15:40that's even worse than getting a bat
15:41signal because now we're confused and
15:43that's why this car ended up by us
15:45let's look at what it looks like in a
15:52this is what we're communicating with it
15:54and it's going right to this Gateway
15:56module and it talks to the engine
15:58control module through these modules
16:01are through these communication lines
16:03now if we test from here
16:06are we testing any of this network which
16:09we may have a problem on
16:11no we're nowhere near it this is why we
16:14can't test from the DLC anymore it's
16:17going to get us in trouble now is there
16:18some cars you can yes but what do you do
16:21first we break down the network
16:23so what else do you notice about this
16:26and this can really confuse people
16:28this really can confuse people the text
16:31said that all of these modules could
16:32still communicate so there can't be I
16:34mean if this network is down these
16:37modules there's no way they're going to
16:38communicate so it can't be the scope
16:40pattern looks good they're not
16:41communicating the network must be okay
16:46well let's look at it again
16:49if this network's down
16:52these modules are not communicating with
16:55if you're communicating here with your
16:57scan tool can you communicate with these
17:00you're communicating on this green
17:04so what I'm trying to hammer home is
17:08we need to break this stuff down before
17:13just because we can communicate with a
17:14module doesn't mean it has a
17:15communication issue think about it like
17:17your cell phone your cell phone has text
17:20and data or text and calling and
17:24messenger and so you can lose one and
17:27you can still communicate that's exactly
17:28how these modules are
17:30look at it like a wiring diagram
17:33look at these serial data lines there's
17:35a bunch of them it's communicating this
17:38is the gear shift module so if it's if
17:41and we're communicating communicating it
17:43through here yeah we can still
17:46let's look at the engine control module
17:49it's on this can bus line this can bus
17:52line this can bus line so you can see if
17:55we have a problem let's say the engine
17:56control module is not communicating with
17:59what on What lion we need to look at
18:01these break it down I mean sometimes you
18:04might even have to print out paper and
18:06use your highlighter but it's if you
18:07spend 45 minutes doing that and less
18:09time with this you will be more
18:11successful I guarantee you
18:14because this is just impossible this is
18:18why this is Step number one
18:20is speed rate or data or all the canned
18:23protocol information can help you fix a
18:25car when you're looking at this no
18:27that last car was fixed with a visual
18:31once we knew that these were the four
18:33lines and these were these were the
18:34modules I communicated a simple visual
18:37inspection showed some mice chewed some
18:43we never even looked at anything with
18:45this and the person before said it was
18:47good it's it's it's super simple it's
18:49like glorified map Reading I know it is
18:51but this is why we're training with this
18:53first to show you how simple it is and
18:55how you can be successful doing it
18:57and if you're thinking
18:59you know what I don't want to do this
19:01network stuff I'll just leave it to the
19:02network guy I'll stick to my powertrain
19:05look what I found when I was looking at
19:07these wiring diagrams and I didn't even
19:09know this existed this is the first time
19:11I've ever seen this look what I had
19:15it's a mass airflow sensor
19:18the mass airflow sensor signal is going
19:20to the engine control module with Lin
19:22now that's on communication lines
19:28engine cooling fan communication line
19:31engine coolant flow valve communication
19:34so we're not going to just be breaking
19:36these communication networks down for
19:37communication problems now we got to
19:39break them down for sensors and stuff
19:43and if you want to make fun of that
19:44escalator being so complicated
19:47take a look at the BMW
19:50I know it's glorified mapping but this
19:52is 75 percent of can bus diagnosis if
19:55you do this you will be successful
19:58so we know we need to divide these
20:01who and they're divided into sections
20:04but let's talk about how they're divided
20:06into sections and why they're divided
20:07into sections and we have to answer this
20:09question because I always get it okay we
20:12have all these modules
20:13we have all of these different cans why
20:16do they have to be that many cans I mean
20:18that's just more confusing wouldn't it
20:19be less confusing if there was one can
20:22with all the modules on it
20:24well let's take a peek at what that
20:27this is what a network looks like when
20:31and networks used to be like this for a
20:34and Not only was it harder to diagnose
20:37but what do you see here I mean yeah it
20:41you know a card game but it looks like a
20:44house of cards to me
20:46modules or communication should say
20:49there's two ways communication fails
20:50either the module has an issue or
20:53there's a wiring issue
20:55now let's say this module has an issue
20:58there's two things modules do these are
21:00short short out or they talk too much
21:03now this module shorts out guess what
21:06it's going to take down the whole
21:08now you lose everything
21:10or if this module won't stop talking
21:12it's going to take down the whole
21:13network and we lose everything you can
21:15see it's like a house of cards
21:18or let's say wiring wise
21:20let's say this is shorted to ground
21:23we just lost the whole network let's say
21:26this is shorter to power now we lost the
21:28whole network and you can see why
21:29they're they're sectioning this stuff
21:31off it makes sense and also let's say we
21:36if let's say this module is bad it's
21:38shorted out how do we find that well now
21:41we have to go through every single
21:43Network or every single module just to
21:45find out which one's bad all this wiring
21:46when if it was sectioned off it'd be
21:51let's think of some real world examples
21:54and this is stuff that I've actually
21:55seen let's say this is your uh
21:58this is your driver's window switch and
22:01this is your PCM that runs your engine
22:04I say you're on your way to McDonald's
22:06and you're you're getting a cup of
22:08coffee before work and the guy who hands
22:10it to you he's got it over full you
22:12squeeze it too hard and you pour coffee
22:13all over your window switch shorts it
22:15out well now your car just died in the
22:18in the parking lot or in the
22:19drive-through and now you got to get it
22:20towed now this one might be easy to
22:22diagnose because you know what you did
22:25but it creates a system that's not very
22:28fault tolerant and it's not very easy to
22:30diagnose so splitting this stuff off I'm
22:32trying to explain that this is actually
22:34now let's look at it let's just say that
22:36this is your PCM or whatever and let's
22:39say this is the media center in in your
22:41back and your kids are back there and
22:42they're watching Paw Patrol and uh maybe
22:45they're watching a DVD and while you're
22:48on your way to vacation
22:49and you think they're just watching what
22:51they're really doing is finding all the
22:52change you dropped and they're finding
22:54it playing a game how much change can
22:55fit in that slot before it's full
22:57because that's a fun game and it shorts
22:58out the entire network
23:01so let's look at how we have it
23:06here's your window switch you spill
23:07something on that you only lose this
23:09network your car still runs your safety
23:11systems still work and now we only have
23:12to diagnose this section of it
23:15or let's say here's your little media
23:17player that has change in it and it
23:19shorts that out now it only shorts off
23:20this section now we still have
23:22everything else and now we just got to
23:23sing our way to Vacation instead of
23:25playing the video games in the back like
23:26they do nowadays it's not so bad we did
23:31still get a case study and this case
23:33study is great because it shows you the
23:36House of Cards example and it shows you
23:38a tricky thing that uh
23:40manufacturers are doing to save
23:42themselves and it also shows you how it
23:45makes it easier to diagnose at the same
23:46time so this is a 2013 GMC Acadia
23:50it's got a no star condition and this
23:53was an actual car that I had
23:55the other symptoms I'll talk about in a
23:57second but it had a no start problem and
23:59it was very intermittent the customer
24:00brings it in he goes every once in a
24:01while I turn the key
24:03nothing happens like okay
24:06so I get the car in doesn't happen I
24:08turn the key thousand times the
24:09battery's about to go dead I'm like I
24:11can't see the problem I'm like is there
24:13anything else on there that you know any
24:14of their symptoms and he goes well the
24:16interior lights go out once in a while
24:19and I have a service object detection
24:23message on the dash all the time
24:25I'm like okay he's like but I don't I
24:27don't really care about that I don't
24:28need service object detection or object
24:30detection it's just the rear little
24:32things in your bumper that are like
24:36for any ways I or for just because I go
24:38when I look at codes
24:39and this is what I have for codes
24:42HVAC radio telematic driver's door door
24:45control remote function rear gate who
24:47cares right this doesn't have anything
24:48to do with running the car
24:50and if you've ever worked on these older
24:52GMS a lot of them come with these codes
24:53stored from the factory and they never
24:55do anything and I didn't really care I
24:57dropped the ball on this one so he
25:00didn't care about his other symptoms so
25:01I sent him down the road and guess what
25:03about a week later the thing comes back
25:09but now I can fix it so it comes in
25:12doesn't start just like you said you
25:14turn the key nothing happens so I get my
25:17this same codes are in there nothing
25:20else that doesn't help but what I do
25:22know is the PCM is not commanding the
25:28I look around and I didn't see that
25:30first and I couldn't figure out what was
25:32wrong all the wiring seem fine
25:34I think it's time we look at this
25:36so what do I do I look at the network
25:38and I look at it as a whole at first
25:41just so I can break it up
25:43and looking at it here
25:45I mean it may take a little while but
25:47the color coding stuff is really nice
25:49all this green stuff is one network and
25:51this will be our low speed Network and
25:52then we have all these gold ones and
25:55this is our high speed Network so
25:57looking at the High Speed network I see
25:59that we have the engine control module
26:02and the transmission control module the
26:04body control module so I'm thinking this
26:06is a network that may have a problem
26:07because I don't know what all those
26:08communication codes I don't know what
26:09network that stuff's on yet so I look at
26:11the High Speed network and there's
26:13there's all my money right there the
26:15engine control module blah blah blah but
26:17they're all communicating and I don't
26:19have any codes for that stuff I do have
26:21the body control module that's setting
26:23the codes that's where those codes came
26:25from the body control module but I don't
26:27really see my problem yet
26:28so I moved to the other side of the
26:30network to break it down
26:32now I'm on the low side but look what I
26:37this looks like that that that house of
26:39cards that I had before this is
26:41definitely that house of cards I had
26:44all these modules on one line
26:47so I start going through and I start
26:49checking the modules I had codes on for
26:52and there they are all the modules that
26:54I have in Gold here are yellow those are
26:55the modules have codes for and what I
26:58also realize is I don't have
26:59communication with anything on this
27:01network so this whole Network's down
27:03someone knocked over the house of cards
27:06so this is a problem this is what I have
27:09but why doesn't the thing not start well
27:11reading through it I figured it out
27:13pretty quickly the stuff to turn modules
27:15on the low speed Network
27:17the theft deterrent module is a module
27:19that reads the key so without reading
27:21the key the PCM says I'm not starting
27:24but look the body control modules on
27:26there too how did I talk to the body
27:28remember what we talked about before
27:31the body control module speaks two
27:34it's one language is out but the one I'm
27:36talking to with the scan tool speaking a
27:39why else is this so good
27:42think about that house of cards if you
27:44take one module out you take out the
27:45whole network if we have separate
27:47modules and a module that can speak to
27:49all the networks we have a tattletail
27:51module a module that can set codes when
27:53one of them or the networks goes out
27:55remember this is a good thing we just
27:57got to break it down
27:58and here's a picture of the BCM you can
28:01see here's the data here's more data
28:04here's a wiring diagram picture over
28:06here you can see we have the low speed
28:07Network and the high speed Network
28:10so all I got to do is figure out why the
28:12low speed Network's out and this one was
28:14kind of hard because it was a house of
28:16cards but I go back to my symptoms and
28:18remember this is another thing if you
28:19can break down these networks into
28:21smaller sections think of the symptoms
28:23that are caused what symptoms does each
28:25module cause or what represent what
28:27could represent what well what was the
28:29one constant that we had that service
28:32object detection message was on that was
28:34the one thing that was always there so
28:37it can't hurt at this point there's a
28:39lot of stuff on that house of cards why
28:40don't I go here first this was this is
28:42the one thing that was always broken and
28:44if I look at it on a communication
28:47here it is it's on a low speed Network
28:49here's the right one talking to the left
28:51one and then the left one talking to the
28:54the low speed Network
28:56and I got lucky I got really lucky it's
28:59not always going to be this lucky but
29:04this module had water in it right here
29:09and then I took the connector off
29:12and there was green fuzzy stuff and some
29:15greasy stuff in there and as soon as I
29:17disconnected it I heard all the lights
29:19and stuff come back on the dash second
29:21uh or the low class small Network went
29:24back and the car started up just fine I
29:26knew what my problem was
29:27and a little more backstory is if anyone
29:30hasn't worked on GM's
29:33every single month from here on out I
29:35found more and more of these this was a
29:36major issue that GM had they built a
29:39house of cars that they didn't break up
29:41luckily this one was easy to diagnose
29:43but here's where this gets really
29:45interesting and I think you're really
29:47going to like this this is this is kind
29:49of funny kind of not funny
29:51a couple months ago and this is what
29:52really sparked this class and sparked
29:54the beginning of this class remember all
29:56the stuff we've diagnosed so far we
29:58haven't even taken out of lab scope yet
29:59we haven't took out a multimeter we've
30:01just been looking at wiring
30:032017 GMC Acadia so same car couple years
30:08newer it pulls into the shop
30:10it's got this object detection message
30:12but it's got a front camera message too
30:14but it's got more it's got more options
30:16so I don't really care but here's my
30:18here's my big money right here I've seen
30:20this 20 30 times before I'm gonna
30:22diagnose in five seconds
30:24but there's no other symptoms present
30:28well maybe it didn't short out that way
30:30maybe it's not showing the whole thing
30:32out but it's still kind of interesting
30:34to me but either way I put my scan tool
30:37on it and it's one of the newer scan
30:38tools to show us topography it breaks
30:41the network down for you
30:43or at least it does a decent job of
30:45breaking it down they're not perfect but
30:49so what do we got here we have our stuff
30:51in red and that's saying this code set
30:54but what do we really notice here
30:56what do we have down here
30:59we didn't have that before
31:02and this is the left side object
31:04detection module right side object
31:11well that's interesting here's the
31:13wiring diagram we had for the first
31:15couple years of this car
31:17here's our object detection modules
31:19here's our house of cards and GM had a
31:22problem with these and they tried to fix
31:23it they started out by telling you to
31:26put some grease in the connector
31:27dielectric that'll solve it
31:30didn't solve it then they had a updated
31:33module they put a sticker over the vent
31:35hole the module to stop water from
31:36getting in there did it help no it
31:40so what do we have now for wiring
31:44that doesn't look like as much of a
31:46house of cards does it
31:48half the modules are missing and if you
31:50look here it looks like the body control
31:51module even isolates the class 2 in half
31:55and where's the other object detection
31:58well it's right here
32:00they don't even talk on the same network
32:02that this one's talking on now they talk
32:03on a separate Network so if this one
32:05goes down it doesn't even pull the class
32:072 or the the low speed down
32:11and we didn't have that no star concern
32:14because look at the immobilizer
32:17now it's on its own separate Network
32:21so they fixed their problem didn't they
32:23by breaking down the network by
32:25sectioning things off
32:27and as much as you don't like it it's
32:30great for us it makes diagnosing this
32:32easier and this is why this is number
32:33one step because if I would have just
32:35went at this with the old stuff or my
32:37old thinking it wouldn't have worked
32:39because things are constantly changing
32:41let's go back to this
32:43here's our house of cards this is what
32:47and this is what they did they took it
32:50out what would you rather do diagnose
32:52this whole thing as one big Network or
32:54let's say this is five separate networks
32:55all we have to do is know where we're
32:57testing and why we're testing and this
33:00is the first step when it comes to
33:02diagnosing this can and I know I've said
33:04it before and I'll say it again this is
33:06just this is glorified map reading this
33:09is just investigating this isn't taking
33:10tools this isn't anything crazy but this
33:13is the this is 70 of fixing can and if
33:16you if you do this if you use this I
33:18guarantee you will be successful now I
33:21hope you liked what you see here today
33:22and if you did please hit that subscribe
33:25button hit that Bell icon and then
33:27you'll get notified when part two of
33:28this class comes out that's we're going
33:30to start talking about the protocols and
33:32the way these things are wired and we're
33:34going to get a little more depth into
33:35the can bus stuff so as always thanks
33:39for watching again I hope you liked what
33:40you've seen here today this is Ryan with
