Unable to see any CAN traffic with M2 on Volkswagen Vento and Chevy Beat

General Discussion
#1

Hi All,

I am newbie to automotive cyber security and after becoming conversant with using canutils and SavvyCAN on ICS simulator , i wanted to try the same techniques on my cars (Volkswagen Vento -2011 model and Chevy Beat : 2012 model).

I followed the instructions on this web page (https://docs.macchina.cc/projects/use-m2-with-savvycan) exactly and everything worked like a charm (e.g. flashing M2 and replaying some CAN packets through it before connecting it to the car) . Used M2RET and SavvyCAN V199 on windows 10 Home edition.

However, i am unable to sniff/capture any CAN traffic when i connect the M2 to OBD on any of my two cars, despite the fact that SavvyCAN shows status as “connected”.

ELM327 OBD adapters work fine with their diagnostic apps on both cars though.

Can anyone please advise as to what i could be doing wrong here. Please do let me know if you need any more information that could help with resolving my query.

Many Thanks in advance of any help you could provide.
Rick.

#2

First of all we need to know what year your car is. The feds Mandated all US cars to be equipped with CANBUS about 2008 and some did start rolling out CANBUS before that. Prior to that your car likely has a different protocol which is not compatible at this time with SavvyCan or canutils.

#3

Hi ,I have tried on both my cars now : Volkswagen Vento 2011 and Chevy Beat - 2012. Used M2RET and SavvyCAN v199 on windows 10 home edition.

Also, ELM327 OBD adapters work fine with their diagnostic apps on both cars though.

#4

Some cars will not talk on the Diagnostic port without prompting. I would suggest you get a Y adapter and plug the M2 into one port and the ELM into the other port. Get the ELM talking to the car and then try to get your M2 to view it.

Once you have that working try it without the ELM and see if it still works. If it doesn’t then you probably need a request command sent to get the information to the Diagnostic port. Your ELM software has this request command being sent and it is running it. You need to identify that command if your M2 works with it in place but not when it isn’t. SavvyCan supports including these “wake” commands.

#5

Hi Rick101,
Did you ever get this issue resolved? I have the same issue with a 2013 Audi A7. I’ve tried the suggestion above using a Y connector with VCDS running on one side the the Macchina with M2RET and Savvycan working on the other. VCDS works perfectly and I presume sends the prompt. Savvycan shows the M2 as connected with green LED on, but no traffic from the car to Savvycan.

I’ve cycled through Buses and speed settings, but no joy!?

#6

I could be wrong but I think what you and @rick101 are experiencing is a gateway. See in the attached A7 wiring diagrams how the can pins from the obd2 port (bottom of page 3) run into that “data bus… interface” on the top of page 4.

They are very common in all modern VW group cars. I don’t personally have much experience with these but the easiest fix might be to tap in somewhere other than the OBD2 port. I would maybe try that right CAN disconnect plug.

I think these cars are also known to have many channels of CAN and that seems to be what we are seeing in the diagrams. So be sure to start with the module or sensor you want and then find a bus that connects too.

Printer Friendly View.pdf (169.5 KB)

#7

Hi Subarubaru,
Thank you for the reply and the diagrams, they will be a great help. I didn’t get to test tapping into the bus away from the OBDII yet but hopefully this weekend and I can report back.

#8

@rick101 @nkiernan, SavvyCAN has a UDS Scan window, you could try sending a Tester Present message, see if you get something back. If you do, you have a UDS-enabled diagnostic gateway.

1 Like
#9

Thanks @alien.technology, I will try this

#10

Hi @rick101 and @nkiernan did you get your issues solved? I’ve got the same issue with a VW T5 and a Triumph Street Twin. SavvyCAN can talk to the M2 but I can’t see any frames coming in. I also tried a UDS scan with the default settings, but without any output.

#11

The VW is probably the same gateway issue. You can either figure out how to work with it or physically go around it and tap in somewhere else.

I’m not sure the Triumph is the same problem though, have you tried different baud rates?

#12

I think I’m gonna give a Y connector (splitter) a try, cause like with the others, an ELM327 works. When the issue really is caused by a disabled diagnostics port, the idea to tap in somewhere else is also worth a try. (Maybe the dash connector is a good point to start. How to find out which wires to connect to is the next problem to solve then.)
No I didn’t try different baud rates. Are there changed in the connection window of SavvyCAN?

#13

I just wanted to share some news: I’ve seen CAN frames in SavvyCAN coming from my Triumph! At the end it’s been the baud rate. I’ve set it to 500k and now it works.

#14

Hi s.eichler,
Sorry for delayed reply, glad you got sorted and it wasn’t the gateway issue. Just to update, I did get a UDS response from the Audi from the OBD port. Tried a Y connector cable also but that didn’t work. Didn’t try tapping in elsewhere as doing savvycan work on a range rover first