CAN pids for turn, stop,backup
 

I've been tinkering with some individually addressable LED chains, and you can do some cool tail light, stop stop light, and turn signal effects. I'm currently driving them with a ESP32 microcontroller at 200MHz, which is a bit of overkill, but its got wifi and bluetooth built in, so a nice chip!

Rather than cutting into the car's harness to monitor when the user turns, brakes, etc, I was wondering - could I make a CAN module that listens to the CAN bus instead so you either only need one wire, or you could plug a wireless dongle into the ALDL port so no wires other than power and ground, if you wanted.

But I'd need to know how to watch for stop, turn, brake on, backup, and so on. I'm sure I can reverse engineer them with VehicleSpy3 if I'm ambitious enough but if it's already well-understood, I'd rather just ask someone who knows!

So... anyone know?

I don't know that info, but this is the kind of thing I get excited about. I'd have to check the schematics, but I think the steering column stalks are on a LIN bus direct to the BCM. So you won't get any info from there. But I'd assume the BCM broadcasts those signals out onto the rest of the car. Certainly to the cluster, since it has to show the turn indicators.

GM does their buses a little weird. It seems like most if not all of the high speed modules have a GMLAN "in" and a GMLAN "out". So if you can get the connectors, you could probably just insert your own plug and play module in between the harness and one of the existing modules. I've thought about doing exactly that for some HMI stuff I want to try.

I've got some stuff that's capable of listening to both the high speed and low speed GM LAN buses. Let me know if I can help. :)