VAG 1552 K-line not switching to positive

Hello,

When I connect a V.A.G 1552 diagnostic tool to the diagnostic connector of my Volvo V70 VII 2.5L diesel, which is an Audi MSA 15.8 model from the year 2001 and first registered on December 20, 2007, the following message appears:

<V>

After entering "00", the display shows [something].

Vehicle System Test - Q
00-Automatic test run >

Then I press the "Q" key, and the display shows:

<Automatischer>
and then, a short time later...

<Automatischer>


Press "Help", then select "Display cycle".

K-line not grounding.
K-line not switching to positive.
Possible causes:
1. The line is connected to the positive or negative potential.
at mass
Input/output stage defective in the tester.
- Choose your self-test!
Automatic test sequence Help
K-line not switching to positive.

Then, when the device is connected to the K-line and doesn't switch to positive voltage, pressing "Help" will display possible causes, etc.

I tested the connection cables (V.A.G 1551/3A) for continuity. All 5 wires have a continuous connection and there is no short circuit between them.

Voltage measured while connected to the power supply, using a probe connected to the brown wire.

View of the pin configuration on the VAG1552 connector.
brown + shielding, 9:00 AM.
gray: 0.0V
yellow 12.3V 12:00 PM
green 11.4V
white 10.1V 3:00 AM

Everything is fine, the ignition key is not in the ignition switch.

Does anyone know what's broken, or what I should check or investigate?
Does anyone know the pinout configuration for both sides of the connector?

Regards,

Andreas

If you have an aftermarket radio in your car, try disconnecting it and then trying again .

No aftermarket radio installed.
Would simply removing the fuse for the radio be sufficient? That way, I wouldn't have to disassemble all that plastic trim just to get to the radio connectors.