ECU Connection Error: Troubleshooting Guide

Hello everyone, I'm new here.

I have set up the interface with version 4.0, but unfortunately, I am unable to connect to the control unit.

It always says:

interface status 3 - no connection to the control unit, or: the control unit is not responding

Now my question: Does version 4.0 actually work? Has anyone here ever tried it out?

I'm trying to read the error codes from my VW Corrado VR6 (although it's not a diesel ). It still has the 2x2 connectors under the shift lever.

During the LED test, LEDs 1 and 2 are blinking.

'Doesn't the Corrado have both a K-line and an L-line? I modified the adapter so that the switching between K/L-line and K/K-line is no longer necessary, and now it only has a K/L-line, as described in the manual.'

Can someone explain how this specific adapter works? I can't quite imagine how the data from the car is transmitted to the PC via the K-line.

Thank you for your help.
Sure, here is the translation of the text from German to English:

'Hello.'

Does anyone have any advice?

Okay, the adapter is working perfectly; I tested it on my workbench. I simulated responses from both the PC and the car, and the adapter shows logical switching states. Based on that, I think I assembled it correctly.

Do I perhaps need to enter something specific in the options of VCDS (formerly VAG-COM), such as the baud rate, etc.?

'Thank you.'
Sure, here is the translation of the text from German to English:

'Hello.'

Okay, so it turns out, I can now access my control unit . I can read the data from the engine control unit and the ABS control unit .

Can anyone tell me where the OBD2 port is located on a VW T4?

'Thank you.'
Sure, here is the translation of the text from German to English:

'Hello.'

Thanks, the website is really great.

Sure, here is the translation of the text from German to English:

'Hello.'

Okay, so it would be great if you could let me know what the problem was in the first place...

I just had to set the VR4 to its maximum setting, and then it worked .

Sure, here is the translation of the text from German to English:

'Hello.'