GM’s Global B (VIP) architecture gets dissected through the lens of real-world module programming and network diagnostics. The host contrasts Global A’s simpler PIN-based security with Global B’s cryptographic SDAC handshake (key-off programming, GM server verification, CAN FD, and MDI-2 requirements). A detailed case study on a 2021 GMC Yukon Denali shows how a camera pinfit issue led to gateway replacement, then SDAC failures blamed on the instrument cluster—forcing a costly cluster replacement and even network “jumping” to complete the handshake. The episode also covers GDS-2 network tools, SPS setup/configuration, and clone-tool/GM server lockouts.
This week on the sow I share a case study on a 2021 GMC Yukon Denali that had a new serial data gateway module replaced. This vehicle has GM's Global B or VIP Architecture, which presents new challenges for technicians when installing and programming control modules. Listen to hear the pitfalls you may run into and which vehicles it applies to.
"This show is brought to you by Auto Rescue Tools and Isaac Rodel. If you've been looking for a programming laptop..."
They’re a company that sells tools for working on cars. The host mentions them for things like programming laptops and diagnostic gear.
Auto Rescue Tools is mentioned as the source for programming laptops and diagnostic-related equipment. In this context, it’s tied to tools used for vehicle programming and troubleshooting across multiple makes.
"This show is brought to you by Auto Rescue Tools and Isaac Rodel. If you've been looking for a programming laptop..."
Isaac is the person the host recommends for setting up a laptop for car programming. The goal is to make it work for different brands of cars.
Isaac Rodel is presented as an expert who custom sets up programming laptops for technicians. The emphasis is on making sure the laptop/software setup can handle multiple vehicle brands.
"If you've been looking for a programming laptop, you're not sure which one to buy or how to set it up..."
A programming laptop is a computer a shop uses to update or reprogram a car’s electronic modules. It’s often needed after replacing parts so the car recognizes the new components.
A programming laptop refers to a technician’s computer used with manufacturer or aftermarket software to reprogram modules. It’s commonly used for tasks like configuration, calibration, and sometimes key/module pairing after repairs.
"You'll also find scan tools, diagnostic equipment, key cutting equipment, and much more."
Key cutting equipment is the machine used to cut a replacement key. On newer cars, the key also usually has to be programmed to work.
Key cutting equipment is used to physically cut replacement keys to the correct blade profile. On many modern cars, key cutting is only part of the job—keys also need to be programmed/presented to the vehicle’s immobilizer system.
"You'll also find scan tools, diagnostic equipment, key cutting equipment, and much more."
Scan tools are devices that let you talk to the car’s computer. They help you read trouble codes and see what the car is doing in real time.
Scan tools are diagnostic devices used to communicate with a vehicle’s electronic control units (ECUs). They’re essential for reading fault codes, viewing live data, and performing certain relearn or configuration procedures.
"Today on the show, I'm going to be talking more about General Motors... this week's episode..."
This episode is focused on cars from General Motors. The host is going to talk about how GM’s newer cars are networked and how that affects repairs.
General Motors (GM) is the vehicle manufacturer at the center of the episode. The host is setting up a discussion about GM vehicle networking and module architecture used on newer models.
"We did General Motors Most Bus last week. This one is also going to be General Motors and it does have to do with networks."
In modern vehicles, “networks” are the communication systems that connect ECUs so they can share data and coordinate functions. Diagnostic work often requires understanding which network a module is on and how communication failures can block repairs or programming.
"So these are fairly new vehicles to the aftermarket. If you work in the dealership world, you probably have had your hands on plenty of them."
Aftermarket means the repair world outside the dealership. The host is saying these newer GM cars are still relatively new to independent shops, so the learning curve can be steep.
“Aftermarket” here refers to the independent repair/service ecosystem outside the dealership network. Newer GM architectures can be challenging for the aftermarket because diagnostic tooling, training, and procedures may lag behind dealership-level access.
"But this came out, I think they announced it in 2019... So once we get up around the 2019 2020 range, it's either going to be Global A or Global B... Now we have something new to deal with... this is much more than just a pin code that's being shared on these vehicles."
GM uses different “platforms” for how the car’s computers talk to each other. “Global B” is one of those platforms, and it matters because it changes how the dealership tools can program and secure the car’s modules.
“Global B architecture” refers to GM’s newer vehicle electrical/electronic platform used across certain model years. In this episode it’s discussed specifically in the context of module programming and security, meaning the architecture affects how modules authenticate and communicate during diagnostics and programming.
"And so you're going to have one of them. Global A we've dealt with quite a bit. I've talked about it as far as module programming goes. And when you compare Global A to B, A is very simple..."
“Global A” is an older GM computer-platform approach. The speaker says its security setup is simpler than the newer one, and it doesn’t apply the same way to every module in the car.
“Global A” is GM’s earlier architecture the speaker has already covered, and it’s used as a baseline for comparing security and programming behavior. The key point is that Global A’s security approach is simpler and not consistently applied to every module, which changes how technicians handle programming.
"But essentially all they're doing is they have a four digit pin number that is hard coded... it's in the data of these modules. And then they share it back and forth."
The speaker says some modules use a simple shared PIN (a four-digit code) as part of their security handshake. If the PINs don’t line up between modules, the car may flag it and cause problems.
In the Global A discussion, the speaker describes a “four digit pin number” stored in module data that modules share with each other. If the PINs don’t match, the car can generate an identifier code and that mismatch can lead to additional issues during programming or module replacement.
"There's also over-the-air updates that I guess I really don't know much beyond the fact that they have said that over-the-air updates are possible with these vehicles."
Over-the-air updates mean the car can download software updates electronically, like a phone. It can change how modules work, but the exact process can be complex.
Over-the-air (OTA) updates let a vehicle receive software updates without a traditional dealer visit. The segment highlights that GM’s architecture supports OTA, but the exact mechanism and service implications may require dealer-level knowledge.
"Now, you actually do have to have specific scan tool with the CAN FD capability, even just to interact with the car."
The speaker notes that even to interact with the car, you need a scan tool that supports CAN FD. This matters because the vehicle’s network uses flexible data-rate communication, so older tools may not communicate reliably.
"So if you're going to be programming on these newer General Motors vehicles, I'd highly suggest looking into getting the actual legit GM MDI-2. They're not that crazy expensive if you work on a lot of General Motors vehicles."
GM MDI-2 is a GM-approved scan/programming tool that plugs into your computer. It helps you talk to the car’s modules the right way, especially for newer GM vehicles.
GM MDI-2 is General Motors’ official diagnostic interface used to communicate with newer GM vehicles for programming and diagnostics. It’s designed to work with GM’s online/service systems, which is why using the genuine tool matters.
"The vehicle I was dealing with was actually a network problem on one of the CAN buses. And it was a kind of a challenging series of events when I got involved with this."
CAN bus is the car’s internal “data network” that connects computers. If it’s having problems, multiple warning lights and symptoms can show up.
CAN (Controller Area Network) bus is a common in-vehicle network used for real-time communication between modules. When a CAN bus has a fault, it can trigger cascading issues across multiple systems.
"...m a serial gateway control module on this 21 GMC Yukon Denali. Shopping replaced it, brand new from GM. ..."
The GMC Yukon is a large SUV made for carrying people and gear, and the Denali is the higher-end version. It has lots of electronics that talk to each other, and sometimes a specific computer module has to be replaced to fix problems. A “gateway” module is basically a hub that helps different systems communicate.
The GMC Yukon is a full-size SUV built for family hauling, towing, and long-distance comfort, with the Denali trim positioned as the more upscale version. In diagnostic discussions, it often comes up because modern Yukons use many electronic modules that communicate over vehicle networks, so a “control module” replacement can be a key step in fixing recurring electrical or communication faults. The mention of a serial gateway control module highlights how system-wide connectivity issues can trigger multiple symptoms.
"...but these GM Global B vehicles, they're actually programmed with the key off. And it is important you do that..."
It means you’re supposed to keep the car’s ignition off while doing the programming. Doing it the wrong way can cause the security steps to fail.
Programming “with the key off” means the vehicle’s ignition state is intentionally left off during the GM Global B module programming procedure. This is important because the vehicle’s power/communication conditions can affect whether the security authentication and module programming steps succeed.
"they have you look at the error message that pops up if it fails. If it passes, just give your thumbs up, you're done with that part..."
The speaker advises technicians to review the exact error message shown during programming failures. OEM programming workflows often provide actionable failure reasons (e.g., security/authentication/handshake issues), and those details are essential for correct next steps and customer communication.
"...This is all listed in the TSB. But the error that you might come up with is that there is a single module causing this to fail."
A TSB is like an official “known problem” memo from the car maker. It tells mechanics what to look for and how to fix a specific issue.
TSB stands for Technical Service Bulletin. It’s an official document from the automaker that describes known issues and the recommended diagnostic/repair steps, including what error codes or symptoms to expect.
"...but it says ECU. And then you look at your code."
An ECU is one of the car’s computers. It controls functions and also stores diagnostic codes when something goes wrong.
ECU stands for Engine Control Unit, a type of electronic control module. In GM diagnostics, “ECU” may be used more broadly in error displays to indicate a control module category, even if the specific module isn’t the engine computer.
"And that's when I was looking at it more closely to my pre scan. And I'm like, Oh, this has a bunch of communication codes in it. After I programmed this module."
Communication codes mean the car computers aren’t talking to each other the way they should. That can happen after programming if a module isn’t fully connected or authenticated.
Communication codes indicate that modules can’t exchange data correctly over the vehicle network. The technician notes the cluster shows a “bunch of communication codes” after programming the gateway, which supports a network/connection problem rather than a purely software issue.
"...is there was a pin fitment issue at the camera on the windshield... the female sides just sort of stretch out a little bit."
A pin fitment issue means the connector pins don’t make proper contact due to poor seating, deformation, or looseness. On camera-related connectors, even slight misfit can create intermittent or permanent loss of communication on the associated network.
"I check it for updates, [1612.8s] it didn't have any updates, I pushed it through anyways... So I program the module, same thing kicks me back. [1622.9s] Hey, the cluster is the thing that's failing."
Programming is when the technician loads the correct software/settings into a car computer. If programming doesn’t “take” or the same error returns, it usually means another module is causing the problem.
Module programming is the process of updating or configuring a control unit with the correct software/calibration. In this case, programming the gateway/module leads to the same failure outcome, indicating the fault is likely in the cluster or related network behavior rather than the initial programming attempt.
"So now the next step is pull a fuse or unplug the cluster, neither of which are a simple task... So okay, I got to unplug it. [1654.8s] Easier said than done, you got to pull half the dash apart"
Unplugging the cluster means disconnecting its connector to temporarily remove it from the car’s network. It’s a way to confirm whether the cluster is the part causing the problem.
Unplugging the instrument cluster connector is used as a controlled test to see whether the cluster is the cause of a failing diagnostic/programming step. The transcript notes it requires significant dash disassembly to access the connector, and that the test outcome determines whether the cluster must be replaced.
"actually [1647.9s] one of them fed power to the MDI two at the DLC. So I can't pull fuses."
The DLC is the car’s diagnostic plug. It’s where a scan tool connects to read codes and communicate with the car’s computers.
DLC stands for Data Link Connector, the standardized diagnostic port where scan tools connect to the vehicle. The transcript indicates that one of the fuses feeding other systems also powers the MDI at the DLC, which is why pulling fuses can unintentionally disable diagnostic capability or other modules.
"...after the security handshake is a network or a module configuration."
This refers to the ordering of programming steps: the security handshake must occur before the gateway performs its network/module configuration. If the order is wrong, the gateway may not correctly “learn” the installed modules, leading to persistent security/communication faults.
"...it looks at all the modules that are listed on the database of GM server for that via for that VIN number."
The VIN (Vehicle Identification Number) is used to look up the vehicle’s configuration in GM’s database. Here, the security gateway uses the VIN to determine which modules should be present, then configures itself accordingly during SPS setup.
"And if there is a module that is on the network that doesn't belong, it'll set an error... It's also going to code and not let you complete that configuration."
This is about the car’s electronics talking to each other. If the car sees something it doesn’t expect—or can’t find something it expects—it can throw errors and stop the setup from completing.
“Modules on the network” refers to the vehicle’s distributed electronics communicating over internal data networks. If an unexpected module appears (or an expected one doesn’t), the vehicle can set errors and block configuration, because the network topology and authorization don’t match what the vehicle expects.
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Welcome to the Automotive Diagnostic Podcast.
We're going to explore ways to sharpen our diagnostic skills, find learning resources,
and hear from experts in the automotive field.
This show is brought to you by Auto Rescue Tools and Isaac Rodel. If you've been looking for a
programming laptop, you're not sure which one to buy or how to set it up, especially if you
want to program multiple brands. You know, you've got some domestic vehicles, you've got European
vehicles, can the same software go on the same laptop? What size hard drive do I need? All those
questions. Isaac's your guy. He can custom set up programming laptops that are ready to tackle any
make or model. I've got one of these laptops myself and I can say that it is outstanding and it
really streamlines the process by having everything you need in one device. So if you're looking for
something like that, I highly recommend checking out AutoRescueTools.com. You'll also find scan
tools, diagnostic equipment, key cutting equipment, and much more. Check out the link in the show notes.
I highly recommend it. Hey, what's going on? Automotive World, welcome to another episode of
the Automotive Diagnostic Podcast. My name is Sean Tipping and I will be your host once again for
this week's episode. Thank you so much for joining me. Today on the show, I'm going to be talking more
about General Motors. We did General Motors Most Bus last week. This one is also going to be General
Motors and it does have to do with networks. But this is really going to be about the Global
B or VIP architecture that we see on some 2020 plus General Motors vehicles. So these are fairly
new vehicles to the aftermarket. If you work in the dealership world, you probably have had your
hands on plenty of them. I really haven't a whole lot, at least nothing too in depth until just
recently. And so I thought I'd share on the show a little bit about my experience, what we went
through real world on a broken car, the things I learned. And I guess probably the most important
thing here is the obstacles that you or your customers might be up against just when replacing
components on these vehicles and something that you really want to be aware of. So you can have
a heads up, you can give your customer a heads up, but I'll get to that. But first, I'll just touch
on Global B a little bit. You can research this stuff, Google it, use your LLM of choice and you
can learn quite a bit. Again, I'll touch on a few things here that are most relevant to us
diagnosing fixing cars, programming modules and especially programming modules. But this came
out, I think they announced it in 2019. As far as what I could tell, there isn't an actual 2019
model with the Global B architecture. Somebody can correct me if I'm wrong, because I did find
some inconsistencies on the information out there as far as what model applies to Global A or Global
B, right? So once we get up around the 2019 2020 range, it's either going to be Global A or Global
B, as far as I'm aware. And so you're going to have one of them. Global A we've dealt with quite
a bit. I've talked about it as far as module programming goes. And when you compare Global A
to B, A is very simple, especially the security measure that they use, which isn't even on all
of the modules on the car. They're essentially just sharing a pin number. And yes, it gets a little
bit more complex than that. And there are certain modules that are very difficult to program if
you're going to try to do them used. But essentially all they're doing is they have a four digit pin
number that is hard coded. Well, I shouldn't even say hard coded, you can change it. But it's in the
data of these modules. And then they share it back and forth. If they don't match up, then you get
an environmental identifier code. And that can cause more problems. You can actually cause that
code to be permanently set in other modules on the car. If enough used modules are put onto a
vehicle, it's operated without changing anything. Anyways, that's Global A stuff. And we're becoming
more and more familiar with the obstacles and the solutions with Global A. Now we have something new
to deal with. And this is going to be quite a bit more challenging because this is much more than
just a pin code that's being shared on these vehicles. It's a fairly advanced security mechanism
that is going to be shared between the modules on the car. Now, the one thing I also was finding a
tough time really getting a solid answer on, and again, lack of experience here. So maybe somebody
else out at the dealership might know the answer to this is, I'm not sure if it's all the modules
on the vehicle that are going to be involved with the security or if it's only a select few.
That's something that I guess I'm going to have to research as I continue to work on these vehicles.
But I will tell you about the modules that I know for sure are involved with this and the ones that
we've experienced issues with. But when it comes to the vehicle platform of Global B or VIP, which
is vehicle intelligence program for General Motors, they introduced some stuff like CAN FD,
which is flexible data rate, where they can actually speed up the amount of data transfer
on a network for a certain period of time. They can change the data rate with the CAN FD.
There's also over-the-air updates that I guess I really don't know much beyond the fact that they
have said that over-the-air updates are possible with these vehicles. When that happens, how exactly
that happens, I'm not 100% sure. Again, if somebody's at the dealer and really knows the
inner workings of this stuff, real world, I'd be very interested to talk to you about it.
But this is the stuff that they've released out to the public that you can find in
aftermarket documentation. One of the things that when they first released this, they basically said
in a service bulletin and some information out there is you need to use the MDI-2 as far as the
interface of the vehicle for programming. Now, you actually do have to have specific
scan tool with the CAN FD capability, even just to interact with the car. But a lot of
scan tool manufacturers have caught up to that by now. Autel and Topton are not going to have a
problem there necessarily. Now, will you be able to do everything? Probably not, but you can interact
the car, you can clear codes. But for programming, it noted that you're going to want to use the MDI-2
and even the older GM interface, the MDI-1 is not going to work on these vehicles.
Now, they did release an approval for the Cardac-3 to be used on it and not to say that you couldn't
use that Jbox on one of these vehicles if you're going to do some programming. I'd still suggest
using the MDI-2 if you have it on one of these. And I even talked to somebody who does a lot of
ADAS work and they were saying, like, if you're doing a front camera on one of these, not only
you have to use, and this is like 24, 25 plus, but if you're programming a front camera that's in
the windshield, you not only have to use the MDI-2, but you have to have an ethernet cable
connected or it's not even going to communicate correctly to the camera. That's not personal
experience. That was someone else telling me that, but that's kind of where this stuff's going and
you're not going to be able to do that with the Jbox. So if you're going to be programming
on these newer General Motors vehicles, I'd highly suggest looking into getting the actual legit
GM MDI-2. They're not that crazy expensive if you work on a lot of General Motors vehicles. So
take a look, see if you can find one. You can find them used, but be careful because there's clones
out there. And if you get a Chinese clone, number one, it's not going to work the same way as a
genuine, but they'll actually shut your account down. They are able to tell if there's a Chinese
tool being connected to the server when you go to program and they'll just turn your account off.
So make sure that you're not doing that. There's a big banner across the front page of GMAC Delco
and they'll, you know, they make it pretty clear that you're not supposed to be doing that. So
anyways, in addition to using the MDI-2, there are some things on the scan tool platform side
that are new about this as well that are, I think, actually more helpful, right? Some of the stuff
is more complex, more challenging, more obstacles, but once you get into GDS-2, which is the General
Motors scan tool platform for, they started in 2013 on some vehicles where you could use this,
maybe even back to 11 on some of them, but it's online platform and you can use a J-Box for it
or the MDI-2. But with Global B, there are some advanced network diagnostic functions
that you can run to break it down by network, see where the problems were, you know, the error
events that occur, and it actually does make things a lot easier, especially considering
how many networks one of these vehicles have. So like I mentioned, starting 2020-2021,
they really kicked off a lot of these vehicles and you can find a list online. Again, I found some
contradicting information on the exact year for each model, so you might have to do some research
if you've got a particular vehicle, but what I do know is in 21, this started for the General
Motors trucks, specifically the SUVs. I think the pickup trucks were another year or two later,
but for the SUVs, GMC Yukon Chevy Tahoe, this is going to be in 21. And with these vehicles,
they have a ton of modules, a ton of networks. And what I mean by that is there could be like
seven or eight different, just tan networks on the vehicle. And they're going to use a
serial data gateway module on these vehicles as well. And this is the central hub for all the
communication on the vehicle. It's going to have all the networks running to it. I was reading on
this, getting prepped for this episode, and it says that the gateway module and the radio
actually have ethernet switches in them in order to connect to different networks on the vehicle.
And they actually are using a form of ethernet on some of these networks. I didn't get involved
with that particular side of it. The vehicle I was dealing with was actually a network problem
on one of the CAN buses. And it was a kind of a challenging series of events when I got
involved with this. We were originally called to program a serial gateway control module on this
21 GMC Yukon Denali. Shopping replaced it, brand new from GM. They actually had some GM
programming capabilities, but they were not able to get this thing programmed. Now,
they were using a Jbox. And although that may have potentially brought some problems in,
we ended up finding there was other issues as well. And I can go through that with you here.
And that's kind of, again, the reason I want to talk about this, because there's some things that
you're going to want to have a heads up getting into this. Now, for a new module on one of these,
you're still going to go into TLC, and you're going to do your normal programming, which you
pick the module, you may have to pick the software details, and it shoves the software into the
module. And again, I'd recommend using the MDI too. And it's pretty straightforward for that
part of the process. Now, once you're done with that part, that's where this changes when you're
on one of these global B vehicles. And the part of it that I really want to touch on here is the
Serial Data Authentication Configuration, or SDAC. And this is where every module on the vehicle,
according to what GM is saying. Again, I'm not 100% sure it is every module, but according to
the literature, it's every module on the vehicle. So is this small body controllers too? I don't
know for sure, but again, I can tell you the ones that I've dealt with. But for now, let's just
say it's every module on the vehicle, they have to pass a cryptographic security check, right?
It's like a digital handshake that's actually verified through General Motors servers, right?
So you need to be connected with an MDI too, have TLC running, the vehicle is, you know,
connected to the programming device, and you're connected to GM server. And what it's going to
is a handshake between all of the modules, the security gateway, and the GM SPS server.
And this is going to verify all of the security keys between all of these modules. Now,
this is where it gets way more complex than just sharing a PIN code. They're using, like, again,
the cryptographic security check, which, you know, quite honestly is beyond me. I'm not the guy to
explain exactly what that means. I'm going to shoot some terms out there that I was reading
about as I was trying to get some notes on this. So if you want to research this yourself, you can,
you're smarter about this stuff than I am, you can research it. It is interesting. I just don't
claim to be an expert and know all the details, but it's using a SHA-256 code for the actual,
like, mathematical function. And it's using a Diffie-Hellman exchange for the information over
the potentially public network. Now, again, if you want to research that stuff and figure out
more details about that, go ahead. But from what I understand, what I had Claude explain to me,
like I was a small child, was that this is a really complex math equation that is hidden from
any person or device that could be viewing it over a network. So not only is the calculation
done between the security keys going to be very difficult to crack, but then it's hidden on top
of that from anything that might be monitoring network traffic. So pretty complex stuff. But
really what it comes down to is after you do the programming on one of these modules,
you're going to have to run this SDAC or the security data authentication configuration.
And that's done through TLC. There's a tab at the bottom, you run it, and, oh, you know what,
I did forget to mention one thing. And you'll see this on TLC if you're doing this, but these GM
Global B vehicles, they're actually programmed with the key off. And it is important you do that,
but it gives you fair warning if you're paying attention at all within TLC that, hey, you
should have the key off. And honestly, that makes a lot of sense to me, programming a lot of modules
to have the key off for programming, you know, you can shut off a lot of electronic consumers
if the key is off. And that probably is the best time to actually be programming a module.
Anyways, it's a little different because most vehicles are going to have the key on for programming.
Anyways, that security data authentication also happens with key off. But you're running it through
TLC. It's a tab at the bottom. If you're familiar with TLC at all, or I should say SPS within TLC,
when you're at the screen where you're picking from the different modules on the vehicle,
this is where you'll see that S stack down at the bottom. It's a tab, you click it, and then it tells
you, okay, we're going to do this, make sure the key is off, go ahead. And then what it's doing is
that handshake between all the modules using the serial data gateway module, the MGI GM server,
making sure everybody's okay, right, is that cryptographic key good between all of them. And
here is where this is where it gets real practical for technicians and shops that are listening
to this, and you're going to program a module on one of these cars. It is a known problem
by General Motors, where when you run this, you will have a failure. And it will be a failure of
particular module on a car or a single module on a car. And basically, you'll get a kickback
saying, hey, it failed. But it will tell you there are some different reasons it can fail.
And there's a TSB, I'm actually going to share the TSB in the show notes for this episode. So you
can read through this, you can save it, you can show your customer, which I think is important.
But they have you look at the error message that pops up if it fails. If it passes, just give
your thumbs up, you're done with that part, it doesn't take very long. This show is brought to
you by automotive seminars. If you're looking to stay up on the cutting edge diagnostic strategies
and techniques, this is the place you've got live four hour seminars that are put online that you
can join in, ask questions, interact with the instructors with some of the best the best,
they've got Keith Perkins, John Thornton, putting on classes like network diagnostics,
mechanical engine testing, advanced electrical testing and GDI diagnostics and a ton more.
And once you purchase one of these training seminars, you can access this at any time that
you want through your account at automotive seminars.com. You can rewatch the training a year,
two years later, which makes this training even more valuable. So I highly recommend you check
this out. The link is in the show notes. It's pretty quick. It's not like it's way faster than the old
10 minute wait that you had to do on GM vehicles. Anyways, if it fails, it gives you an error message
of why it fails. And there's various reasons can fail beyond a single module, there can be a server
issue. I think there's like an unknown error. This is all listed in the TSB. But the error that you
might come up with is that there is a single module causing this to fail. And I had actually
run into this on Escoids a couple of times where the telematics module would fail. And I believe
it's the K73 is the Elf in the Merrick code. And that's how it presents it to you after the failure
is you'll get an Elf in the Merrick code. You can just compare it to the module list
right there in SPS and say, okay, this is the module that it's referring to. It doesn't spell it out
for you, but it says ECU. And then you look at your code. Now, what it's telling you is that
that module is the odd man out. He is not in agreement with everybody else. And the unfortunate
part is if you have one module who doesn't agree when you do that security handshake,
it fails and you're going to have codes on and it may even be a no start condition,
depending on the vehicle. I have had them where they still start. So I don't know exactly what
determines a no start. Maybe it's a period of time after either way. If you're going to be
sending the vehicle out the door, you can't leave it this way. You're going to have lights,
you're going to have codes, you'll have issues. Now, what the TSB instructs you to do is to
look at the module that fails and number one, check the module that failed and see, here's the
thing, I probably should back up and say this, this might not even be the module that you replaced.
Okay. And that was the situation on this particular GMC that I was dealing with.
And I'll tell you more about that specific car, but let me finish with the security handshake.
When you get that failure, that might not be the module that you replaced, that you're programming,
that had some sort of issue on the car. It could be another one that otherwise was functioning.
Okay. So we'll come back to that, but keep that in mind that the one that failed
the security handshake could have been just fine before you attempted to do the security handshake.
Now again, this is outlined. This is a known problem with GM. What they say to do is check
it for an update. If there's an update, update it, try the STAC again, which also when it does that,
it attempts it three times and it'll give you the old GMB bonk if it fails. But you check the update,
you go back in, you try it again. If it still fails for the same module, then you are either supposed
to pull the fuse or unplug the module from the network and attempt again. And there is a caveat
to unplugging. I'll mention that. We'll dive into a real car here. So that's the process of doing
that security handshake. And that is a problem that you might run into. Now, why would you want
to know this? Well, let me go into this real car and explain why. So we originally called in to do
the security data gateway module, which is the central hub for all the communication on the car.
We do the programming. That actually goes through just fine, not an issue. But when we went to do
the security data handshake on it, we actually got a failure for the cluster. And so this is
when I shifted to really looking at all the modules on the vehicle. And I actually branched off
into a die at this point, because when I was really looking at all the codes on the vehicle,
after I had programmed the gateway module, I couldn't do this security data handshake. And I go,
and it failed for, I think it was P16, which is the instrument cluster. So I was going to go check
the instrument cluster for updates, and see if there's any codes in it or see what I had going
on the vehicle. And that's when I was looking at it more closely to my pre scan. And I'm like,
Oh, this has a bunch of communication codes in it. After I programmed this module. And I was
wondering, is this, you know, have I not completed all the steps that I need to. But I also asked
the shop, I'm like, Hey, what were you guys trying to fix? They're like, Oh, we had communication
for the camera, like we couldn't talk to the camera and the setting is lights and stuff. And
we had determined that it had something to do with the connector at the security gateway module.
And they had actually, unfortunately, mashed down some pins on the original. So we couldn't
even plug the original in. But I was saying to them, I'm like, Hey, because I recognize the
series of modules that I couldn't talk to, I'm like, this might, this problem might still be
here. If this is what you were dealing with before, and you kind of looked at it, it's like, Yeah,
I think that is the same problem. So now I have a halfway programmed module, I can't use the original,
and I think I still have the original problem. So I decided to look at the network a little bit,
and he wanted me to try to figure it out while I was there. And what I ended up determining,
at least part of my problem at the moment is that one of the independent can buses, because
there are several on this vehicle, I think it was five plus separate can bus networks.
I couldn't talk to anything on that network. And that was actually can eight. Now they didn't
have all eight, but this was can eight. And this is going to be obviously your gateway module,
that's every can, but it's going to be the front view camera windshield module,
image processing module, and the forward radar sensor. So it's actually, as far as the amount
of modules on the network, pretty small. And I couldn't talk to any of that stuff. And again,
this is where the network diagnostics function within GDS to it's actually really helpful
to break this down. Pretty simply, but look at wiring diagrams to and say, Okay, these are the
modules I can't talk to. And this is, you know, the network, they all live on it, let's see what's
going on with this particular network. And it was relatively straightforward. It was an open on
the network. And it was something that I've seen on GM vehicles quite often, is there was a pin
fitment issue at the camera on the windshield. And I have a feeling that's so common, because
those cameras get so hot, and the pins are so small, that the female sides just sort of stretch
out a little bit. It could also be from being disconnected and connected. But there was a
pin fitment issue at that camera, which we ended up fixing and that fixed that network. So I think
that was the original problem. But the gateway module been replaced the original damaged. So now
we have to program this new gateway module. So again, I've got communication of the stuff that
was originally giving them trouble. And I have the gateway module with its initial programming
can't do the s stack. But I'm going to try again now that I fixed this other network problem.
I attempted it gives me the b-bonk. And I still have the same module that's failing is p 16 for
the cluster, instrument cluster. Now, the instrument cluster has no codes in it, has nothing wrong
with it that I can tell, besides the fact that we won't let this pass. And I check it for updates,
it didn't have any updates, I pushed it through anyways, I just was like, well, I'm here, I'm
going to program this and see what happens. So I program the module, same thing kicks me back.
Hey, the cluster is the thing that's failing. So now the next step is pull a fuse or unplug the
cluster, neither of which are a simple task. Okay, pulling a fuse, you can't do it because
there's two fuses, and both fuses feed other things on the car that would need to be powered in order
for this to pass. So pulling fuses does not kill just my cluster, it kills other things, actually
one of them fed power to the MDI two at the DLC. So I can't pull fuses. So okay, I got to unplug it.
Easier said than done, you got to pull half the dash apart on this to get to the connector at the
cluster. And so I tell them that I'm like, Hey, this is the process that we've got to take now.
And here's the deal, if we get to and we unplug it, and it then passes the SDAC, according to
this technical service bulletin from GM, it says to replace the module. And we have actually seen
this to be the case with the telematics modules quite often, where we unplug them, and it passes
and you replace the telematics module. And unfortunately, you can't just plug in the
bad module after you're done, everybody's going to have codes for Hey, this, you know,
this does not belong incorrect. And I identifier, there's an issue with this particular module,
they all need to be online, when that handshake happens. Okay, now you can pass it, right, or
and I guess you could leave that module off the network, but of course, you're going to have
codes and I can't just leave the instrument cluster off of the network. So that's an issue,
right. And I'm explaining this to him that like, Hey, if we get here, and we prove this,
you're going to have to replace the cluster. He's like, and this is this is the part right here
that I'm doing this episode for so that you can get ahead of this, when you're in this type of
situation, you know, with your customer, whoever that might be is he's like, Well, there was nothing
wrong with the cluster. Like, why would I be buying an instrument cluster for this? And
this is where, you know, I've taken a little bit of time to research this stuff and explain that,
Hey, there's an online security handshake that happens with these modules when you are replacing
one. And it doesn't matter which one you are replacing, that security handshake has to happen
between all the modules in order to get that one, you know, together with everybody else.
And what seems to be happening for what reason I don't know is some of these modules and GM lists,
the telematics, the instrument cluster and the airbag is being some of the more common ones,
they will not, you know, give this thumbs up there. I don't know if it's the calculation
that's wrong. I don't know, I'd just be speculating as to why, but something about the modules does
not agree. And you have to get a new one, you put the new one on there, and you go through
the programming and it works just fine. But that's adding a module in that was otherwise
working. There was nothing wrong with it before, but now you're saying that I have to do it. So
for me, coming in programming these vehicles, I now have to warn customers ahead of time and
actually made up a little sheet and a diagram and an explanation so that we can shoot that to them.
If we're going into program something on global B and be like, Hey, please read this,
because we're going to need your authorization before we get going, because there could be
a module who is working now, but he's not going to agree to the security handshake. And there's no
way around it. You're going to have to replace that if you want everything working, even if that
wasn't your problem, right? Security Gateway was the thing we were replacing. Camera was the actual
problem. So I mean, been nice if we could have identified that and avoided all of this, but
you know, is what it is. But now you got to do a cluster too. And he understood, you know,
again, had to explain it to him because this is new. This isn't how older GMs necessarily work.
I have had this happen on side, side object detection modules where you replace one and then
the other one doesn't agree with the hardware level and you end up having to do both. But
this is just going to be more common on these vehicles. And again, the telematics module
really comment on these things to see this. So he gets the dash apart and I had to leave. I come
back. And here's the other tricky part about this is you can't just unplug the cluster. And I'm sure
this is true of other modules as well, especially on GM can architecture, because they still like
to daisy chain the network through the modules. What that means is if you unplug the module,
you broke the network into two pieces. So that security data handshake is not going to work
for that either. You're going to have to jump the network together, which is what I had to do.
I jumped the pins together so I could complete the network without the cluster and it passed.
Okay. Now you could take a roll of the dice and say, Hey, it's failing for this module,
just get that module. And that's an option. But this is my like first real adventure into one of
these. And I don't know for sure, is it going to pass once the cluster is off the line? And it did.
It gave me the thumbs up. But of course, now I plug the cluster in and everybody's coding for
the cluster like, Hey, something's wrong here. I think they're, they do list an actual code.
It is a you 1962 is what's going to set. And again, their point and fingers at, Hey, the cluster is,
you know, not agreeing to the security handshake. So the cluster needs to be replaced at that point.
And they're going to get a cluster. I haven't even finalized this one.
One other thing on the security gateway module itself, there is a configuration that you have
to do with SPS after the programming. And I don't know if you could do it before or after,
but the order of the process is after the security handshake is a network or a module
configuration. And so what it does is it looks at all the modules that are listed on the database
of GM server for that via for that VIN number. And then it learns which modules are on there.
And it's just a setup feature that you run. If you are in SPS and you click on the serial
data gateway module, it's just set up and it configures it to all the modules on the vehicle.
All the modules have to be plugged in at that point in order to configure them.
And if there is a module that is on the network that doesn't belong, it'll set an error.
How do I know this? It was throwing an error for the telematics module. Okay. And this is just
a little side adventure. This isn't even the main point of this, but you might run into it.
And so the telematics module, which I mentioned has had problems on other vehicles before.
It was saying that that vehicle, there are that modules on the vehicle,
but it wasn't listed on the database and you're supposed to call GM's
tech line if that's the case. And I did not want to sit around and do that. I suppose I could have,
but I went under, I unplugged the telematics module and I ran the configuration again. It said,
yep, cool. We're all good. So I don't know on that one what I'm going to come up with.
And that could be another instance where, hey, we got to do a telematics module too.
The only codes I had when I left the other day were for the cluster. So once they get the new
cluster, we're going to try to button everything up. But you might run into some issues with that
module configuration too. The other thing I found is you try to run that when modules that are
supposed to be there are not there. It's also going to code and not let you complete that
configuration. And you really can't utilize that vehicle properly if you don't complete that.
So where does that become a problem where I see in the future? If you have modules that are just
dead, not working for whatever reason, right? They're old, they broke, customer decided they
want to fix them, but you've replaced the gateway module for something. It's going to say, hey,
I'm looking for a side object detection module, but I don't see it. I can't complete this. I can't,
you know, I can't do this. So would you then have to buy, you know, all new modules so it's
complete on the network? I don't know. That's another piece of this. This is an additional
piece to the security handshake that you'll have to deal with on one of these vehicles. So
it's getting crazy out there. And I guess the reason I'm doing this help you be prepared
if you get involved in one of these vehicles. Maybe you got some experience and you can throw
some advice out there for everybody listening. Feel free to reach out to me or you can post
it in the Facebook group. But that's where I'm going to wrap this one up today. That's Global
BGM and my first real adventure with one. But I'd like to say thank you out there to everybody
for listening. Really appreciate it. But that out of the way, let's get out there and start
fixing the world one car at a time.
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