VAGCom: No Control Unit Found - Troubleshooting

Hello everyone.

I have a small problem.
I tried to access the control unit for the parking assistance system.
STG 76.
However, I'm not able to connect.
Even during the car scan, it cannot find the control unit.

In my opinion, the number is correct. In other Superbs, the number 76 is associated with this model.
Even with a complete search, nothing could be found.

Does anyone happen to know a solution for this?

Sometimes I have problems with the parking assist system.
However, troubleshooting becomes relatively difficult without being able to directly interact with the system.

Thank you in advance for your efforts.

Hello.

Is the K-line possibly interrupted? Is the PDC (Parking Distance Control) installed from the factory or added later?

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

"MFG" is an abbreviation for "Mit freundlichen Grüßen," which means "Sincerely" or "Best regards" in English.

Hello,

What exactly does VAG-COM report when accessing address 76? Does the control unit return any data, and then the connection is interrupted due to errors, or does it simply display "Control unit does not respond"?
Have you ever tried accessing the control unit (STG) using the diagnostic tester at a VAG workshop?

Best regards, Rainer.

Hello everyone.

The PDC (Parking Distance Control) was factory-installed.

The car scan shows "Control unit not responding."
"It's as if there were no parking sensors installed."

Could it be that the control unit is integrated into the comfort control module?
(Just a guess) It's supposed to be Stgnr.:76.

I've been to the dealership before to get issues with the PDC (Parking Distance Control) fixed.
They gradually replaced all the sensors and then the entire wiring harness.

But I haven't been to the workshop for that reason yet.

It also only fails to work occasionally.
I also believe that dirt on the sensors is unlikely, because I regularly wash my car, and the parking sensors were still working even when the rear was very dirty.
(Or sooty)

Okay, if the wiring harness has been replaced before, I suspect that the "K" line simply wasn't reconnected. Since it's not needed for operation. Or was only the wiring harness between the control unit and the sensors replaced? If so, that wouldn't be relevant. Try putting the car in reverse while you're reading the data. It's possible they used the reverse signal for power. In that case, the parking sensors would only respond when the car is in reverse. If that's not the case, the only solution is to check the entire wiring harness.

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

"MFG" is an abbreviation for "Mit freundlichen Grüßen," which means "Sincerely" or "Best regards" in English.

As far as I know, only the wiring harness between the sensors and the control unit was replaced.

Hmmm. Reverse gear, I might give that another try.
If the radio is turned off, VAGCom won't be able to detect it.

I probably could have figured that out myself, right?

I'm going to test it out and will get back to you later.

Hello everyone.

I just got back from my car.
Despite attempting to shift into reverse, the system cannot be activated.

Still getting "control unit not responding".

Does anyone have any other ideas on what else I could do?

Hello.

The only thing that could be interrupting the K-line signal is a break in the wire, or the control unit (STG) might be faulty. I suspect the K-line wire has been cut.

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

"MFG" is an abbreviation for "Mit freundlichen Grüßen," which means "Sincerely" or "Best regards" in English.

Hello pa-mm6.

So, I don't really think the control unit is broken. (Or, to put it another way, I don't want to believe it. )
Because, in 95% of cases, the PDC works perfectly fine.
I just wanted to investigate the reason for the missing 5%.

A severed K-line is likely more difficult to deal with.
Finding that will probably be a bit more complicated.

I didn't actually want to pull the entire wiring harness out of the car.

Is that a single line or two?
If we had a way to measure the capacitance, we could determine the location of the fracture based on the measured values, right?

HI.
K-Line has only one cable. At the parking sensor connector, there should be a connection for ignition power, a reverse signal ground, the K-line, and possibly a trailer hitch connection. The second connector is only for the sensors. I suspect that the power supply or the K-line might have a broken wire or something similar. I would first check the connector to see if there's anything wrong there.

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

"MFG" is an abbreviation for "Mit freundlichen Grüßen," which means "Sincerely" or "Best regards" in English.

Here is the pinout of the power connector:

T16c/1: black/blue wire from fuse 5 (positive).
T16c/2: li/br to the warning tone generator, slot 2.
T16c/3: ---
T16c/4: ---
T16c/5: brown/blue wire from the socket for trailer operation (only needed if you have a trailer hitch to disable the parking sensors).
T16c/6: sw/bl (reverse signal (RS))
T16c/7: ---
T16c/8: br (mass)
T16c/9: black/blue wire from fuse 5 (positive).
T16c/10: Connect the alarm sound generator to slot 1.
T16c/11: ---
T16c/12: gr/ws (K-diagnosis line)
T16c/13: ---
T16c/14: ---
T16c/15: ---
T16c/16: br (mass)

Thank you for the information.

That's absolutely fantastic how things sometimes work out here.

I will gradually check everything over the course of next week.

I'll get back to you later.