Canbus to GM Class 2
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Canbus to GM Class 2
Hey all, first post here, so hopefully not too dumb of one.
Has anyone looked into spoofing the GM Class 2 data before? I have a 2007 GMC Canyon here that's running a standalone ECU but the BCM and IPC are Class2 only.
I have the abbility to send custom Canbus data, and I was thinking that it should be possible to use an arduino or such or convert that into serial? (I've done this to get some Canbus info into some old dyno software before). I did a bit of searching around and I don't see specifics of the GM Class 2. Would anyone here have some insight?
The lack of something already existing makes me doubt if its even possible, as I'd image that there would be a reasonable up-take on a product that could acheive this.
Has anyone looked into spoofing the GM Class 2 data before? I have a 2007 GMC Canyon here that's running a standalone ECU but the BCM and IPC are Class2 only.
I have the abbility to send custom Canbus data, and I was thinking that it should be possible to use an arduino or such or convert that into serial? (I've done this to get some Canbus info into some old dyno software before). I did a bit of searching around and I don't see specifics of the GM Class 2. Would anyone here have some insight?
The lack of something already existing makes me doubt if its even possible, as I'd image that there would be a reasonable up-take on a product that could acheive this.
- antus
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Re: Canbus to GM Class 2
Class 2 is OBD2, VPW. Being both CAN and VPW are both OBD2 it should not be too hard to change the headers from one to the other and transmit the same payload. You'll need to figure out what the data packets look like and put together some hardware, but there are multiple VPW hardware implementations out there. Some kind of ELM type clone platform should have all the right hardware too but you'd need to write your own or modify existing firmware for purpose. You could develop a POC on a pc with an interface of each type or then refine it in to a single hardware solution or just go straight to hardware. However its possible your BCM and IPC are ALDL not vpw/class 2 so worth confirming. There is some code I posted for an arduino aldl to can on the forums that would give you a starting point if thats the case.
Have you read the FAQ? For lots of information and links to significant threads see here: http://pcmhacking.net/forums/viewtopic.php?f=7&t=1396
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Re: Canbus to GM Class 2
If I'm not mistaken, the Colorado/Canyon pcm "speaks" both CAN & Class2 - CAN for comms between the TCM and some other modules and Class 2 for the IPC and BCM. Maybe you can piggyback in the stock ecm as the translator
eta - it may actually be the Trailblazer I'm thinking of that had a mix of Class2 and CAN.
eta - it may actually be the Trailblazer I'm thinking of that had a mix of Class2 and CAN.
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Re: Canbus to GM Class 2
I beleive the Trailblazer SS has Canbus between the PCM/TCM but the PCM is then sending everything over Class 2 to the BCM/IPC.
My info says that everything on this vehicle is Class 2, single wire only. Are tools available to "look" at that data? I have various Canbus analyzers and am familiar with that, but I don't have anything that works these single wire systems.
I'm really just looking at the idea of sending out a Tach, Speedo and Coolant to the factory dash like we can on the later Canbus cars.
My info says that everything on this vehicle is Class 2, single wire only. Are tools available to "look" at that data? I have various Canbus analyzers and am familiar with that, but I don't have anything that works these single wire systems.
I'm really just looking at the idea of sending out a Tach, Speedo and Coolant to the factory dash like we can on the later Canbus cars.
- Gatecrasher
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Re: Canbus to GM Class 2
GMT355 and Hummer H3 were class 2 until the mid cycle refresh in 2008. That coincided with the US gov mandating CAN for diagnostics. So they switched the ECM, TCM, and FPCM to CAN, added CAN to the diag port, and used the ECM as a gateway to the class 2 network. Trailblazer had CAN a little earlier.
I've used an OBDLink MX and some aftermarket software to read the class 2 data on my 09 H3. If you're looking for sniffer tools, it might help to look for them under it's formal name. SAE J1850 VPW. It was used in GM and some Chrysler vehicles. J1850 PWM was used in Ford. It's similar but incompatible.
You can buy or find a copy of GM's standard doc for older class 2 and class 2 / CAN mixed systems. It's GMW3119. It has the full protocol definition. But it might be overkill if you just want basic cluster signals.
I'd be surprised if someone hasn't already made the thing you're talking about. With all the engine swaps into older cars, there's a real need for this. Those signals are all standardized, so you shouldn't need something Colorado-specific. A converter built for any early 2000s GM vehicle should work.
I've used an OBDLink MX and some aftermarket software to read the class 2 data on my 09 H3. If you're looking for sniffer tools, it might help to look for them under it's formal name. SAE J1850 VPW. It was used in GM and some Chrysler vehicles. J1850 PWM was used in Ford. It's similar but incompatible.
You can buy or find a copy of GM's standard doc for older class 2 and class 2 / CAN mixed systems. It's GMW3119. It has the full protocol definition. But it might be overkill if you just want basic cluster signals.
I'd be surprised if someone hasn't already made the thing you're talking about. With all the engine swaps into older cars, there's a real need for this. Those signals are all standardized, so you shouldn't need something Colorado-specific. A converter built for any early 2000s GM vehicle should work.
- antus
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Re: Canbus to GM Class 2
Its very similar to what GM did with the previous generation in Australia, which is why I mentioned ALDL. Our commodores had J1850 VPW Computers (in some cases, ALDL in others) but the rest of the vehicle bus was ALDL. Then there was a module called the PIM that translated some messages between the two busses. In this case it sounds like they did very similar for VPW and CAN. It'd be beneficial to look at ECM pinouts and see if it has VPW and CAN in the PCM, or if there is a module like our PIM that sits across both busses and translates.
Have you read the FAQ? For lots of information and links to significant threads see here: http://pcmhacking.net/forums/viewtopic.php?f=7&t=1396
Re: Canbus to GM Class 2
I have been looking for a bi-directional Class2 to CANBUS translator for a while but not found anything that suits so am having a go at making my own.
- Gatecrasher
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Re: Canbus to GM Class 2
Let me know if you guys need some sample log data to work with. I can pull it off my Hummer and annotate it against the spec docs I have.
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Re: Canbus to GM Class 2
How far along are you with this? I'm a complete noob with this sort of thing but I don't mind giving up some time to help with the project wherever I can.
Re: Canbus to GM Class 2
Not very far at all.tuner-fish wrote: ↑Wed Jan 29, 2025 5:44 am How far along are you with this? I'm a complete noob with this sort of thing but I don't mind giving up some time to help with the project wherever I can.
I have really only had a play with CAN and Class2 separately.
Ill try get some form of HW together this week so I can run some basic tests and report back.