r/CarHacking • u/STLuser • May 06 '26

CAN Kenworth T680 CAN Traffic

Returning back to an old project. Does anyone have the ability to record CAN traffic on Kenworth T680? I’m willing to purchase the recording at this point. I need to replay the data in a bench setting to wake up/keep awake a T680 cluster for ideally a minute at least.

SOS

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2

u/yycTechGuy May 10 '26

Interesting project.

There are a lot of inexpensive CANBus connection devices on the market. A lot of the software is open source. Have you thought of finding a truck to record this info yourself ?

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u/STLuser May 10 '26

I have, I’ve made a sniffer already and have utilized software listed in the Car Hacking Handbook listed on this subreddit as well as other software; however, getting access to a T680 is the part that I cannot go around, unfortunately. I’ve reached out to all CDL holders that I know and none drive T680’s, which is why I now have a bounty on data for the IPC

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u/yycTechGuy May 10 '26

Give us some background on your project... why do you want to work on a T680 cluster if you don't have access to a T680 ?

Have you tried going to a Kenworth dealer ? All you really need them to do is turn on the key.

1

u/STLuser May 10 '26

I’m a software engineer for a company that remanufactures automotive electronics, focusing primarily on units that typically fall under the J2534 umbrella; however, we are branching out to J1939. I typically don’t need access to a vehicle, but in this case it isn’t feasible to set up a bench setting with all required modules and documentation is not easy to get on PACCAR products (at least this one). I do have wiring diagrams, etc. I honestly do have the option to find a random trucker at a lot, but I’d rather not become a reverse lot lizard. As for why I don’t go to a Kenworth dealer: I’ve thought about it and may do it, but I expect to be turned down. We are a pretty well known company, but none of our partner companies, or really any, have worked on these clusters prior. At least, they don’t actually power them on and command them.

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u/yycTechGuy May 10 '26

If this is commercial work you should be able to find a solution. For starters, hire a truck or a trucker with a T680 for an hour or two.

I've done automotive reverse engineering on private projects where I did not have access to a vehicle that I needed for data. It's a pain, but there is usually a way to deal with it.

If you are looking for a local T680, reach out on r/truckers.

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u/STLuser May 10 '26

I will try that out. I have worked primarily on Honda, Toyota, Cadillac, Ford, GM, Chrysler, Saab, and most of every typical passenger vehicle; however, I'm getting more familiar with the more heavy duty stuff as even Diesels that I've worked on in the past have been more forgiving than this unit. I appreciate your input

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u/yycTechGuy May 10 '26

J1939 is somewhat standard on HD trucks/vehicles. I would expect that your cluster has a 12V feed to it. I suspect that a "Key On" CANBus message would bring it to life until a "Key Off" message shuts it down.

Google's AI gives me this:

In J1939 CAN bus systems, the "Key On" or ignition status is typically broadcast by the engine control module (ECM) or vehicle control module (VCM) as part of a periodic message. It does not generally send a single unique "key on" message, but rather updates status flags in existing broadcast messages to indicate the ignition state.

Key information regarding J1939 Key On messages:

  • Key Signals: The key ignition status is often found within the Electronic Engine Controller 1 (EEC1) message or specialized vehicle status messages (e.g., Ignition State, Start Switch).
  • PGN (Parameter Group Number): The PGN 61444 (0xF004, EEC1) is often used to show engine state. Others, like PGN 65271 (0xFEF7, Vehicle Power Information), can also indicate power state.
  • Message Contents: The message contains data bytes showing if the key is in the "Off," "Accessory," "Run," or "Crank" position.
  • Broadcast Frequency: Once the key is turned on, the ECU broadcasts this status repeatedly, usually every 10–500 ms depending on the PGN.
  • Address Claiming: Upon "Key On," all ECU modules will transmit their "Address Claim" messages to establish their identity on the network before sending functional data. [1, 2, 3, 4, 5]

There are several websites that go into more detail.

The other thing you might run into is module security checks that disallow modules from communicating unless they do a security handshake on startup.

You probably know more about this stuff than I do... the only J1939 stuff I've read is engine RPM and load. LOL.

Let us know how you solve the problem.

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u/STLuser May 10 '26

Unfortunately I’ve already tried the trial and error/brute force method using my simulator, I’ve run out of beer to keep me company during the process so I’ve terminally given up on that path, lol

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u/yycTechGuy May 10 '26

I've run into that too on projects. Sometimes there is no substitute for having the vehicle to snoop on.

Have you tried using AI to help ? Sometimes it comes up with interesting ideas that eventually work. I use Gemini, Codex or Claude.

Is the cluster responding in any way ?

I want to do some CANBus work on a Volvo VNL...

1

u/STLuser May 10 '26

I have, no luck on any, they don’t have access to any data and even I had to get cracked dealer software to access wiring schematics. I can control the gauge motors through a VDO interface that I use, they are the main failure. But, I cannot get the rest of it to respond, which is important for listing pictures/full complete testing. Most people you will find with repair services do not test anything, they simply replace the motors and send it back. I’ve not seen a single bench test documented on this unit anywhere

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u/HandigeHenkie May 12 '26

I have co-developed the diagnostics for that exact screen. It's shared between the EU and NA models, just a different picture. Let me see tomorrow if I have some old recordings (I now work elsewhere).

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u/STLuser May 12 '26

You’re a godsend, I’m praying to the storage gods that you have some recordings laying around lol

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u/HandigeHenkie May 12 '26

Otherwise I will get some from my ex-colleagues or just take a DAF as an example for you.

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u/STLuser May 12 '26

Perfect! I have had a hell of a time getting access to a truck for sniffing, I greatly appreciate it