VW CAN Gateway / OBD Socket

Hello everyone!

I have a basic question about the CAN bus at the OBD socket of VW vehicles (Golf V, Touran, Passat).
Do all the data packets transmitted within the car (regardless of whether they originate from the engine, infotainment, or comfort CAN bus) pass through the OBD connector, or are some of them filtered by the CAN gateway?
I would like to eventually tap into the wiring harnesses for the auxiliary heating system in a VW (Golf V, Touran, Passat).
Since I don't own a car like that, I have to do it on someone else's car.
It would therefore be ideal if I only needed to connect to the OBD socket to do that.
You can't just connect to the comfort CAN bus like that.

Can someone please answer this for me?
Edit: An der OBD2-Buchse liegt nur der Diagnose-CAN an, der macht von sich aus gar nichts.

LG
Maxx.

Hello.

The VW diagnostic connector has CAN lines connected to the gateway, which handles the communication and translation between different speeds, and also relays information from the engine CAN bus to other systems like infotainment or comfort controls.
Certainly for all vehicles of newer models, including the GOLF V.
See http://shop.dieselschrauber.de/obd-faq.php.

Sure, here's the translation:

'Best regards,
HG'

The signals are not constantly present at the diagnostic connector; instead, the corresponding frames are only forwarded to the OBD interface after a diagnostic session is started. This makes sense, as it indicates that an OBD-compatible device is now connected and expects data.

The corresponding protocols must be followed, and the session setup should be designed according to the specific details.

Of course, not all data is available there; the traffic would be too high for the diagnostic gateway, which handles multiple CAN buses with different speeds, and the diagnostic system connected to it would be difficult to manage.

The OBD interface is not the most suitable place for your own experiments; it's better to use the interior or comfort CAN bus instead, even if it's potentially more difficult to access. However, doing so allows you to create your own dedicated connection.

Regards,

Mike320

Hello Mike320.
Well written.
But aren't we all mixing things up here?
The pinout of the diagnostic connector is certainly well-known.
Does an OBD-compatible device necessarily have to communicate via CAN bus?
AND the transport protocol is not responsible for handling traffic.

That's why we're all always looking for IDs.
where senders and receivers are located.

And how does VW handle software updates for its vehicles?
'Not about ODB, but it can also be done through...'
Diagnostic socket???


That's why I thought it would be nice if the Canhack adapter could simply be plugged into the diagnostic port.
And 'lauschen' might be right about the start.

CU HG.

Hello everyone,

I'm currently reading a response to an old post of mine on 'Lichtjahren' that I want to comment on again. It's important to first take a look at the relevant ISO specifications, especially the complete ISO 15765 standard.

Hello Mike320
...
Does an OBD-compatible device necessarily have to communicate via CAN bus?
...


This is very manufacturer-specific. At V****wagen, for example, old technology is constantly repackaged and sold as innovation, so at the time of the post, there were still many cars rolling off the production line with older, serial OBD diagnostics. However, I had been working with a Stuttgart-based manufacturer for years, where OBD = CAN.


...
AND the transport protocol is not responsible for handling traffic.
...
That's why we're all always looking for IDs.
where senders and receivers are located.
...


... another innovation from Wolfsburg, but whether it's their TP1.2/2.0 or the actual standard ISO15765-2, the IDs are not defined in the TP but in the vehicle's data matrix. Furthermore, there are no senders and receivers in the traditional sense in a broadcast-oriented protocol like CAN; instead, any node that needs the message sets the corresponding filter mask.


...
And how does VW handle software updates for its vehicles?
'Not about ODB, but it can also be done through...'
Diagnostic socket???
...


ODB (Onboard Diagnostic Bus) = diagnostic connector...


...
And 'lauschen' might be right about the start.
...


... and here, whether it's K-Line or CAN, without a session initialization, nothing happens. In the case of K-Line, it's even important, depending on the SG type, whether to use a SlowInit or a FastInit!

Best regards, Mike320.