Collaboration on CAN Frame Decoding

General Discussion
#1

As we’re decoding messages, what’s the best way to collaborate? A big spreadsheet on google docs, github text files, pastebin, SavvyCAN’s DBC files?

And for these forums, what’s a good way to organize those discussions? You could have a forum/category/tag for each manufacturer, but those messages can vary from one model year to the next.

And finally, a question for the Macchina guys, what are the legal concerns with posting the CAN data? Are we free to post whatever we find or could an auto manufacturer issue a takedown notice or take other legal action? I noticed in some of the code you post on github you’ve removed the CAN frame IDs (https://gist.github.com/macchina/ac0db2bc45774836d6fe2a5758b12e06)

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Arduino code for starting a car
CAN on a 2006 Chevy 1500?
#2

I am hoping to have a web site up shortly to receive log files and try to do some things with them.

I want to process them and try to determine some different information. I also hope to use them for other projects too so I will post more information about that when it is up and running.

Caniverse is an open garage project that will hopefully have a place to store all of those definitions in Kayak format.

Oh and the stuff they removed was because they didn’t want to be responsible for someone trying the code on their car and causing grief if it doesn’t have the same codes.

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#3

Good questions. I agree with redheadeddrod in the hope that Caniverse turns into exactly what we have been looking for.

You’re both correct on why we removed some ID’s, we have heard conflicting reports as to the legality of hosting this info and we are always in fear that someone will do something reckless with examples we post.

We are probably being overly cautious, but it’s probably good to start that way. As a community we will slowly develop norms for dealing with these issues.

Arduino code for starting a car
Arduino code for starting a car
#4

Eh I doubt theres anything wrong with sharing that info.

The only thing you can do with that code is spoof an RVS (remote vehicle start) request. You cant drive the truck when its in RVS, and it’ll shut off after 10 minutes anyways…

Theres no way you’re going to be able to actually steal a car like this, with a macchina and a couple lines of Arduino code…

The GM immobilizer challenge/response (between the ECM and BCM) its 4 bytes and it has to take place within 100mS. And there are TWO different occurrences of this challenge/response. On low speed SWCAN between the TDM (theft deterrent module) and BCM, and then a second algo happens between the BCM and ECM on high speed CAN.

Thats why cars rarely get “hotwired” now…its so much cheaper and easier for a thief to just buy a tow truck and official looking repo-man costume or something.

#5

I agree, we are not worried about people stealing cars with the code. That’s not what I was referring to when I said “recklessly using code”. I was talking about readhead’s point.

#6

Well, I think this advances the knowledge on CAN bus decoding…

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#7

I think this should apply to VAG CAN too.

#8

no…each manufacturer completely makes up their own ID’s and CAN framing handlers…

That GMLAN bible is only for first gen GMLAN architecture, Global-A changed all of the SWCAN stuff again. So that “bible” doesnt even apply to all GM’s.

#9

:sob: I was hoping something was similar other than electrical layer. It seems not.

#10

Yep… It is older architecture. Global A is a new world.

I co-wrote the bible with Foxdie.

Been a while since I even looked at it but i have started playing again. I pulled a canlog from a 2017 GMC and ran it though some code I am working on - it’s totally different!

I am open to edits on the Bible. Send them my way. I have a sample log from my Caddy and that new truck on github. I want that project to evolve into a gateway between my car and the internet. Car emails me drive logs, low fuel, low tire alerts and the internet sends to car important messages, SMS alerts, etc…

CanLogs

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#11

I will certainly be interested in anything you can get from your CTSV as I have an '09 CTS myself. Will be used in any of my CANBUS or SWCAN stuff that I do although I do have access to other vehicles at work once I create a plug in logger that can log the data for me automatically.

#12

The GM immobilizer challenge is not where an attack makes sense. If one wants to bypass the immobilizer, a better way would be to attack the firmware to avoid the authentication together.

#13

Correct…takes all of 3 minutes with EFILive/HP Tuners to reflash the ECM with a calibration that has immobilizer disabled.

#14

17 posts were merged into an existing topic: Arduino code for starting a car

#19

I’m trying to get some logs when GM Onstar pushes directions to the in car nav system… Anybody out there able to collect those logs?

#23

2 posts were merged into an existing topic: What car(s) are you working with?

#33

What “codes”?

I HIGHLY doubt things are actually different, people are probably just confused about how everything works.

Most likely just a VIN mismatch between the BCM and VCIM that onstar’s servers are complaining about.

06-12 impala, 08-13 cts, 06-11 dts, 08-17 express van, 07-16 acaida, 07-16 traverse, 07-14 GMT-900 truck/SUV, 08-09 pontiac G8, 08-09 SRX, 08-09 Equinox, and half a dozen more…

Literally identical electrical system and communications architecture.

They all use the exact same Denso BCM, door modules, HVAC modules, (albeit with some different trim/cases, but the guts are the same) etc.

Thats why GM’s internal designation for the electrical system is “common-architecture-1”. Because 90% of mid-2000’s to early/mid-2010’s GM cars/trucks/SUV’s all used the exact same modules and CAN communications structure.

The only mid-2000’s to early/mid2010’s GM vehicle lines I can think of that never used CA-1 at some point during some year range were the corvette, caddy STS, colorado, trailblazer.

Hell, the Express vans are still using it today! Figure the architecture was spec’d out and BCM’s and stuff were designed circa-2001-2002…thats pretty impressive its still in mass production 16 years later.

Every other GM car/truck has gone to Global-A by now though. Global-A uses the same 33.3k 29-bit SWCAN hardware layer as CA-1, but the messages/arbitration ID’s are different.

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#34

Some people were reporting unreasonable numbers for some features. So SOMETHING is different. I would have to re read the message thread but some were reporting things like the fuel tank showing 25 gallons free when only an 18 gallon tank or showing negative values for interior temperature when it was actually 70F outside, stuff like that. Again these are not exact examples but the type of things they were complaining about. But all in all they worked for the important stuff. Such as starting their car etc.

#35

Huh weird…

On the temp thing, I dont think the onstar app even shows temperature?

Should only be oil life, fuel remaining, MPG, odometer, tire pressures…and of course remote lock/unlock/start.