CANBUS codes

[dmoney]

I started outfitting Wranglers used for high country and ranch security applications back in 2010. It was pretty simple back when lighting controls were based mainly on relays and switches. Now days, oof. One of the key features my clients like is the ability to “black out” their vehicles when working security on a high ridge, or when they would otherwise be highly visible, etc.

So I’ve been toying with a device I purchased called a Canny 7.2 Duo. Basically, it’s a device that you can connect to the bus and transmit or receive messages to control vehicle functions. For example, sending something like 291 00 46 2B 00 00 28 00 00 would turn the parking lights off.

It can also be used as a CANBUS gateway, which is what I’m working on. Say I have the device connected to the Jeep and to my laptop, and I issue the command to kill the parking lights. They go off, but come right back on because the parking light switch is on and the BCM sees the command coming at a fairly quick rate. That’s where the gateway comes in to play. I have the device sitting between the bus connection to the BCM. During normal conditions, it simply passes messages from the bus to the BCM as normal. However, when I activate a preset voltage or ground input on the gateway module, a program starts running and it will filter out predetermined messages from the vehicle to the BCM. For example, if the Jeep were operating normally with the parking lights on, that means the BCM is receiving a binary message several times a second on the canbus to keep them on. If the driver were to flip a switch connected to the gateway, the gateway would see that binary command on its way to the BCM, filter it out, and in turn, begin issuing the command to turn the parking lights off a few times a second. Pretty neat stuff that can be accomplished without using what used to take 50 feet of wire, relays, tape, enclosures, etc.

What I’d love to find is some sort of documentation on Jeep’s canbus protocol/message format, etc. Currently, it takes a TON of time and effort sifting through thousands of codes, watching for minute changes to determine what does what. Just curious if anyone has ever gotten their hands on something like that?

Sponsored

 

[JonW]

Boy, this brings back memories. I did a lot of reverse engineering on the LX platform CAN bus many years back. The best way I found for identifying the messages you're looking for is to write your software to learn what ID's and values are being transmitted, then just monitor for changed bytes. This way, when you press a switch to activate something, you'll see very few packets coming through. You can also do it by filtering for groups of ID's and only watching a few ID's at once. I wrote a piece of freeware years ago in Delphi that is still available for download at http://www.can232.com/?page_id=72 . Search the page for "CANDE". While you may not need the software, you might get some ideas from the screenshot of how I gathered ID's and did filtering. If by chance you are using Delphi, I can send you code for a more advanced version that can also use 2 USB CAN interfaces to do real-time filtering.

 

[four low]

Uh O. Remote Control, "Life Size"...

 

[dmoney]

Boy, this brings back memories. I did a lot of reverse engineering on the LX platform CAN bus many years back. The best way I found for identifying the messages you're looking for is to write your software to learn what ID's and values are being transmitted, then just monitor for changed bytes. This way, when you press a switch to activate something, you'll see very few packets coming through. You can also do it by filtering for groups of ID's and only watching a few ID's at once. I wrote a piece of freeware years ago in Delphi that is still available for download at http://www.can232.com/?page_id=72 . Search the page for "CANDE". While you may not need the software, you might get some ideas from the screenshot of how I gathered ID's and did filtering. If by chance you are using Delphi, I can send you code for a more advanced version that can also use 2 USB CAN interfaces to do real-time filtering.

Ya, I'm able to get on either the C or IHS buses, and can issue commands that work on the IHS bus (dim the backlighting, turn off the radio screen, etc.) but can't seem to control any exterior lighting as of yet. I'm connecting directly to the star connectors (respectively) behind the glovebox, so the gateway isn't the problem. Argh... Continuing to probe!

 

[jmccorm]

Ya, I'm able to get on either the C or IHS buses, and can issue commands that work on the IHS bus (dim the backlighting, turn off the radio screen, etc.) but can't seem to control any exterior lighting as of yet.

Hey! I've started working on a CAN bus utility called Lasso, so I'm really interested here. Were you able to make any more progress with this? Any good CAN codes sniffed out while you were working on it?

Sponsored