GM Can info & knowledge share

[hjtrbo]

Try looking at can id 0x195 if present. Bit 56, length 16

[Canticicant]

Unfortunately 195 does not come up as a CAN ID in my logs. I also don’t see any instantaneous fuel data broadcasted, to use as a substitute, either. I will try polling for the missing data I need once I figure that out a bit more.

[hjtrbo]

How about 0x1ef or 0x3b9?

[Canticicant]

Those are also not in any logs as IDs. I do see those particular combinations plenty throughout the logs but I don’t understand the data they might be conveying or what the request was to have the info get sent out. In the GMW 8762 1EF, the MAF data, is called a request type data. So I guess I have to request it. Just don’t know how yet.

[Gatecrasher]

I apologize for missing 0x1EF and 0x3B9. Thanks hjturbo for catching those.

With that said, what year vehicle are you working on? I've got a 2009 Hummer H3, and 0x1EF isn't available there. But on my 2017 Corvette (and my prior 2014), it's a standard broadcast message from the ECM. Looks like 0x3B9 is a diesel message.

[hjtrbo]

You can use service $1A
00 00 07 e8 02 1a 90 as an example returns the vin.

[Canticicant]

So this is a 2017 Silverado HD 3500 with L96 engine, E78A ECM. Thanks for the request example. I’ll have to try to figure it out.

[Canticicant]

So I finally found the 3110 doc and that seems to have all the request and response info one could need to experiment and get any PID they might need. I’ve decided for the time being to not pursue a request and response situation just yet since I am able to get all the info I need from the bus by sniffing only. I am using 3D1, Instantaneous Fuel Rate, start byte 4, start bit 3, length 12 bits. I convert this to milligrams per second and then derive airflow from it based on current lambda. The info I’m watching will be enough to accomplish what I want for my project. Thanks for the help!