VAG-COM: Correct Wiring Diagram?

I've been looking around the forum and trying to gather information for building my own VAG-COM adapter, but unfortunately, I'm finding a lot of conflicting opinions. Does anyone know where I can find a complete, tested build guide?

'Thank you.'

Hi,
They are all running (more or less).
The circuit does not yet exist.
The latest version of Ulf (see link) seems to handle more combinations (STG <-> Notebook/PC) than the original version by Jeff Noxon.

Ulf is currently working on a version without optocouplers, and I want to build one using the Motorola driver (MC33199). When they will be finished (especially mine ) is still uncertain. Whether they will be better remains to be seen.

Best regards, Rudi.

Does anyone recognize this circuit? Is it any good?


http://hal9000.vc-graz.ac.at/3rdfloor/projects/diagnose/Diagnose-Interface.htm

Hi,
It's an implementation of Jeff Noxon's design, using components that are readily available (in Germany).
I use a similar setup and haven't had any problems with it so far. Whether it will work with your specific STG/PC combination, you'll need to test.

Best regards, Rudi.

Rudi wrote:

Ulf is currently working on a version without optocouplers.

Hi everyone,

Yes, that's correct.
The basic concept is now finalized on paper, but building and testing a corresponding prototype will take me a few more weeks due to personal time constraints.

If there is an urgent need for a glimmer of hope.
(so that all previous solutions fail for a particular customer, even though their respective control unit is not listed on the official VAGCOM problem list).
and Rainer were willing to include a circuit that only runs in my theory into his website, I could soon upload the circuit to my computer and email it to him.

However, in that case, each user would be a real "test pilot" and should, if necessary, provide not only superficial (offensive) "doesn't work" responses, but rather as detailed symptom descriptions as possible, and potentially suggest solutions. Furthermore, all "electronics experts" would be invited to discuss the circuit and contribute improvement suggestions .

Can I also connect all the wiring, plugs, etc. to a regular desktop computer? Unfortunately, I don't have a laptop, but luckily my car is right next to the window of my room. I could connect it with a 10-meter long COM cable. Is something like that possible?

'Thank you.'

Hi,

Sure, you can. The program and the adapter don't care, and 10 meters shouldn't be a problem with a serial connection.

If you don't already have the cable, and you want something universal, there are adapters available that convert from a serial 9-pin connector to TP connectors. You can then connect any standard TP cable (which are quite cheap) to it, allowing you to achieve considerable distances without having to buy expensive new cables.

Muss always had to run back and forth between the car and the computer .

Best regards,

Jan.

Where can I find the connection point on the side of the car? I have an Audi A3 1.9 TDI.

Year of construction: 1998.

Hi.

The connector looks roughly like a giant, 16-pin RS-232 connector made of plastic.

It should be located somewhere within easy reach of the driver's seat, possibly behind some panels or covers.

where can I find the connection on the side of the car? I have an Audi A3 1.9 TDI.

Hi,

The diagnostic port is located at the rear end of the storage compartment, underneath the ashtray. Carefully remove the plastic cover, and the two hooks on the back will easily break off.

Regards,
Peter.

How about the connection now? So, if I have the board described here, it has a connector for the computer on one side and a connector for the car on the other. But how can I connect the board to the car? Can I simply connect pin to pin using regular copper wires? Or do I need a special cable for that? If so, where can I find such a cable?

'Thank you.'

Hi,

A special cable is not required for VAG diagnostics via the K-line, as it operates at a speed of 9600 bits/s and with a sufficiently high signal level, making it technically non-critical in terms of radio frequency.
You can connect the vehicle-side connectors of the circuit board to the diagnostic connector, as indicated in Ulf's schematic.
Currently, there's a DIY kit for an OBD2 diagnostic connector available on eBay for 12 or 15 euros.

Regards,
Peter.