I'd like to spy on my car's CAN bus. I already have an OBD-II to bluetooth dongle that lets me use the Torque Pro Android app to see some OBD-II diagnostics, but I'd like to dig a level deeper and see the actual CAN bus messages. Googling has found some CAN hardware/software combos that are sold for this purpose, but I can't seem to find any that plug into the OBD-II port, and I'd like to use the dongle I already have if possible, though if that's not an option, I'll buy whatever works.

OSX would be my preferred OS for the software piece, but I'll do Android or (sigh) Windows if necessary.

If you already have a dongle that doesn't do CAN bus, how do you think it will be able to do CAN bus?

What you have now sounds like OBD-II only. Different tools can get more info from the same connections. e.g. my BMW can have a generic reader attached to get the legally mandated stuff via OBD-II but with specialised tools and interfaces lets you get into all the custom stuff like seat memory, lock while driving etc.

What car? Is there a CAN bus connection on the OBD-II port that you know of? Should be pins 6 and 14. If something like a VW/Seat/Skoda/Audi/etc there are specific tools and interfaces to look at. e.g.
http://www.ross-tech.com/vcds/canbus.html

Unless you just want to look at raw CAN?

The car is a 2012 Dodge Charger. I thought the dongle might actually have access to the CAN data even if it's not being used by most applications, but it looks like Chrysler vehicles use multiple independent CAN buses that probably don't communicate all the way back to the OBD port, so it looks like I'll have to tap into what they call the "CAN-B" bus to get the info I'm after.

There seem to be some folks who've done some similar projects in the registration-only area of canhack.org, so I'll probably pursue further lines of inquiry there. Was hoping it would be easier, but I guess I'm not surprised they'd firewall most of the car's systems off from the OBD connection.

Yeah, looks like the radio connector has CAN-B pins on it. That's probably my best bet.

Well the OBD port can is for diagnostics. Assuming they can read everything that way, do firmware updates etc, that's probably enough for them.

Surely there's a way to "gateway" from the CAN-C at the diagnostic port to CAN-B bus and that's how the diagnostics work?

Interesting, though this from the canhack.org forums



makes it sound like the path of least resistance is probably to just tap into the CAN-B at the stereo connector, since I can't find any reference to what these "special commands" for getting through to the other buses are. I think it's also a lot easier to get to than the TIPM as well, so that'll be where I start.

Right but the TIPM connects to the OBD-II so should be easily accessible. Under the dash on the driver's side?

If getting direct to CAN-B is easy enough then yeah cut out the middle man.