Interfering braking system

Moin! The new one again (with a problem, which hopefully every second one here had before)...

I finally managed to register my treasure today and it's called -V836 ;-)

But that joy was short. After a week's time here in the garage, I took a grip, and today the first exit was on. After 10 sec. However, my broad grin passed away abruptly because: I was sold the car with the words "...and if you brake strongly the BC reports a mistake in the servo system". Yes, I had read the American manual to the UFO brakes and thought relatively confident that it was the bomb that was over. It's just a pity that it was supposed to be twice as expensive today at VAG as I thought it would be, and I first said that I'd postpone the purchase. So far, the BC only started after the usual tests: 3x strong standing on the brake - beep beep beep. But now I'm driving out of the garage and THE FAHREN the little shit yells at me, I should slowly get to the next V8 base...

After 500m I remembered that during the round view in the engine compartment I found two battering plugs and also an unplugged probe below the main brake cylinder. Of course, I could do it from plug shape, cable length, bend etc. Assign immediately. But after 700m I had to stop screaming loudly.

Is it possible that the salesman of my treasure has been so right to fuck with me? Could it be that in a defective servo pump the BC noticed this sensor just after the engine start over above and this was intentionally jammed before my test drive to cover up this error?

I finally took some brake samples in an industrial area on wet road tonight and let a mate drive for cross comparison: is it normal that a V8 brakes as if it had no brake force gain? I turned off ABS for the test and made an emergency brake at 50. I almost broke my chair out of the holder, so I had to step in! This morning in my old 80 with low pressure amplifier I remembered the braking power on the pedal also much less...

So, what's all that messed up? Bomb? Servo pump? Amplifier on the main brake cylinder? All at once? And who am I gonna shoot first? Me? This #§&$% seller? Both of us?

:,-(

(will [hopefully] continue...)