Low Speed Can Bus on 2014 Camaro
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  • Hi, just got my CBT and have been learning quickly about Can and GMLAN. From what I've been able to glean it looks like my car model has a High Speed 2 wire Can Bus on pin 6 and 14 of the DLC and a single wire Low Speed Can on Pin 1.

    The messages I'm primarily interested in are things like windows and radio controls which I believe are sent on the low speed Can Bus. Can I wire one of the buses to just Pin 1 or am I SOL?

    Thanks a lot for any knowledge!

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  • LucasBest, I will be there with you shortly as soon as my CBT shows up. I have a 2014 Silverado and there may actually be three CANBusses available over the DLC port on your vehicle. Previously I have used a Pi with a PiCAN adapter, but am only able to interact with one bus at a time. If you still need it, I will let you know what I find on the other ports.

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  • How you guys coming with the low speed single wire bus and the CBT?

    I'm interested in instrument data which I believe is transmitted from the ECM over high speed, then to the display as low speed from the BCM.

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  • KidTurbo,

    After going over the service manual I realized the messages I'm interested are actually on a completely different bus called the CGI bus and it's not available through the OBD II port. I'm going to try removing my control panel and getting to it that way - just waiting for the connector and terminals to get here in the mail.

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  • LucasBest, I finally broke down and purchased the service manuals for the 14 Silverado. Not sure on your Camaro of course, but here, the windows, hvac controls, heated seats and etc are all running on LIN busses. In the wiring diagrams, however it shows there being multiple independent LIN busses, like one for the window switch and motor, and another for the locks for each door independently with the BCM being the hub/switch for those networks. Looking at the telematics schematics and the location of the RKE receiver lead me to believe that those devices are sending CAN messages to the BCM, which then translates and routes the messages to the LIN busses behind it. I haven't yet discovered the msg_IDs for those yet, but I have about 15-20GB worth of log data to sift through.

    On a side note, wondering how different the BCMs are between GenV engined vehicles, on the 6-14 pair, do you see msg_ID 0x140? On the Silverado it is the status of the exterior lamps. Auto, Manual headlamps, turn signal and direction, brake lamp status, and the output from the light\dark sensor. If you see the 0x140 to be the same in your vehicle, I can give you the list of the IDs I have deciphered to this point. I have found many, still looking for a whole lot more!

    I have difficulty with the GMLAN bible that lives on the "googles"... Need to spend some quality time with it at some point.

    KidTurbo, I hope to get my SWGMLAN figured out in the next few weeks. Will let you know what I find.

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  • I have access to mitchell on demand if anyone needs some help. I need to figure this out as well. The BCM is vital for communication.

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  • Sorry for bumping old thread but wanted to give my experience with GM LAN. I've poked and prodded around on a 2010 Camaro SS using Intrepid Vehicle Spy. I tapped into the HS CAN network by building an extension harness to go between the ECM connectors and the ECM itself. I'm definitely not a CAN expert by any means and really only know enough to be mildly dangerous but I was able to identify and reverse engineer all 19 of the ECM CAN messages and also identify many of the BCM messages as well. The scope of my project at the time was to replace the stock ECM with aftermarket EMS for performance tuning so I didn't mess with infotainment stuff at all. I was able to implement my aftermarket EMS into car and make the engine start and run and the car stayed happy even with the stock ECM completely removed from the car.

    Anyways, my point in all this is that even though these other messages or channels may be on slower speed networks, I think they still propagate on the HS CAN. For instance, one of the things I needed to do was get all the stock gauges to work (tach, coolant temp, fuel level, trans temp, oil temp, and oil pressure). The gauges technically lived on LS CAN but everything coming out of the ECM/EMS is on HS CAN so there must be some carry over between the two. Unfortunately my knowledge and experience is too limited to fully know how exactly it works but I know that there are 39 other messages that are coming from other nodes besides the ECM.

    Hope this helps in some way. I'd love to see the GM LAN stuff further developed.

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