When CAN-bus sniffing brake system fails and engine can't turn on

[PJv50]

Hi guys!

I am learning about CAN and the goal is to reverse engineer some CAN message so I could program some custom gages or use steering wheel buttons in a raspberry pi based infotainment system. 

So I bought a cheap knock-off ELM327 OBD reader (not knowing it was not really suitable for CAN) and did some research.  A couple days ago I installed a linux driver that turned the ELM327 into a best effort CAN device. I did some CAN sniffing/dumps (on v50 1.6D) which worked for a few minutes and then crashed. This is not my main problem, my main problem is that a few times my dash turned into a Christmas tree, I got warnings of brake failures and my engine stopt working (the only thing that I heard working was the oil pump). After opening and closing my door everything went back to how it's supposed to.

Now my question is why did this happen? Is it just because of the cheap OBD reader which interfered with the can network, is it a volvo thing?  And which device should I use for CAN sniffing? Also any reading material or tips are always welcome.

thanks in advance,

PJ

[Tristan Scott]

On 11/19/2020 at 7:02 AM, PJv50 said:

Hi guys!

I am learning about CAN and the goal is to reverse engineer some CAN message so I could program some custom gages or use steering wheel buttons in a raspberry pi based infotainment system. 

So I bought a cheap knock-off ELM327 OBD reader (not knowing it was not really suitable for CAN) and did some research.  A couple days ago I installed a linux driver that turned the ELM327 into a best effort CAN device. I did some CAN sniffing/dumps (on v50 1.6D) which worked for a few minutes and then crashed. This is not my main problem, my main problem is that a few times my dash turned into a Christmas tree, I got warnings of brake failures and my engine stopt working (the only thing that I heard working was the oil pump). After opening and closing my door everything went back to how it's supposed to.

Now my question is why did this happen? Is it just because of the cheap OBD reader which interfered with the can network, is it a volvo thing?  And which device should I use for CAN sniffing? Also any reading material or tips are always welcome.

thanks in advance,

PJ

I'm trying a similar thing (want to control haldex) but with an arduino using a seeed canbus shield v2 and have been gathering info about this topic slowly...  From what I've read, obd port is not the best place to intercept CAN data on these cars.  On my 2004 S60R, there isn't even a CAN Hi to the obd port so you would have to manually splice into a CAN Hi wire to gain true access to the network.

I am a total noob when it comes to this subject but can offer up what I know.  Why don't you try going the arduino + canbus shield route for your can sniffing endeavor?  It's very cheap to get into so not much money lost if it doesn't work out.

[rbodor3]

It sounds like you overloaded the CAN network. CAN wiring should all be shielded and grounded. Could be that, or could have to do with frequency you're requesting data off the network.