Hi guys,

 

So I am trying to connect CAN HW [Vector VN1640 or Dauntless CAN 2.0B] to the Gateway [SDLC - OBD] port, using CAN H [Pin 6] and CAN L [Pin 14], however I am unable to record any traffic [data].

I've attached for reference, the wiring schematic which Skoda/VW/etc vehicles use, noting that it is traditional CAN High / Low config, and for now assumption that Bus Speed is 500k.

 

Has anyone had experience with connecting a data logging device, using SW on a PC, and if so, what HW & SW did you use?

 

Does the CAN Gateway need some kind of wakeup message on the Diagnostics CAN connections before it will start talking?

Possibly, but I wonder if it's as simple as VW [in line with ISO protocol] only provided data when requested?

I know with other makes [Ford/Subaru/etc] you can receive freely data via the OBD port.

I'm now thinking the solution is to tap into the CAN prior to the gateway, ie. raw CAN data.

9 hours ago, Hye993 said:

I'm now thinking the solution is to tap into the CAN prior to the gateway, ie. raw CAN data.

Which CAN? The Gateway also acts as a CAN switch between multiple CAN buses - Powertrain, Comfort, Infotainment, Extended, ...

If you connect to any of the canbuses directly and start sniffing,  you will definitely see data transfer assuming you pick the right baud rate.

 

Ages ago I grabbed a cheap can transceiver and was able to see data on my bench set up...

 

It's possible the diagnosis canbus only responds to requests but I'm a little surprised there is zero traffic. Did you try different bus speeds and do you have a scope to check nothing is happening?

@PetrolDave Essentially I want the Powertrain CAN, so I'm just going to make a patch loom to tap into this CAN only.

@langers2k Yes RAW CAN is the go, most of that stuff [Powertrain] is 500k, but I've got access to a Vector CAN+SW, which auto detects the Baudrate. The reason there is Zero traffic is because OBD Port only responds to requests [annoying! but in line with the CAN protocol - as confirmed with SW Engineers @ Ford].

Please keep us posted on how you get on.

 

Im looking into something similar, particularly on the Octavia 4 (NX) trying to find the message that the 5F module sends out when I press the start-stop button on the screen. (And also monitoring the start/stop status as shown on the screen also).

@sunshinedave The Vector stuff is rather pricey, but I'm able to find used units for sale on eBay. The catch is that there is perhaps little to no support from Vector, or the HW is outdated and no longer serviced/recognised by Vector.
In addition to this, you'll need a spliiter [Y-Cable] which is available on eBay too, but you need to be really careful when you poke and prod into Raw CAN.

The original post I put up because I was having issues with using the OBD port with the HW I'd purchased, I've resolved this issue with a FW update.

Good to know.

 

Let me know if you find a good CAN H/L pickup point for the power train bus. I know in the past Audis have had pins available in a connector on the side of the dash. I was in there recently on my O4 VRS, passengers side anyway and there was no such connector. I’ll have to check the drivers side, but it would be nice if we didn’t have to back-pin anything to get onto the bus.

@sunshinedave so the splitter I've bought from eBay goes between the gateway and the wiring harness, which is located below the steering column.

Per the diagram below which i've pieced together, it would be easiest at the Gateway based on all the traffic coming in and out.