Valve Actuation: Control & Operation

Hello everyone!

"Which of you knows which connection is correct?"

a) When the solenoid valve for the shut-off valve is energized, the shut-off valve closes.
b) The solenoid valve for the shut-off valve is energized -> The shut-off valve remains open.

Purely from a logical standpoint, option b) makes more sense because when the engine is switched off, the power supply to the MSG (Motor Steuergerät - Engine Control Unit) is cut off via relay 109. How, then, would the shut-off valve be actuated?
Upon engine start, the valve would immediately be activated to prevent the increasing vacuum in the system from causing the shut-off valve to close prematurely.

Is my understanding correct or incorrect?

Thank you for the information .

Regards,
Alex.

I'm not sure, but my observations suggest a).

When you park the car, the tailgate closes automatically and opens again after 2-3 seconds. It is pulled closed by a spring force and vacuum. - I once held the tailgate closed on my T5 to see how much it would shake if it weren't closed.

It remains open permanently when the vehicle is parked.

It would be pointless to keep them powered on for days at a time, solely based on their electricity consumption.

Perhaps there is a shut-off valve solenoid valve capacitor in the control unit.

The cooler fans might continue running even after the system is shut down.

m;

Hello everyone!

'Which of you knows which connection is correct?'

a) When the solenoid valve for the shut-off valve is energized, the shut-off valve closes.


Here I am!

Relay 109 is exclusively controlled by the EDC (Electronic Control Unit). The EDC can maintain voltage for an indefinite period (theoretically several minutes) even after the ignition is switched off. During the control unit's after-run function, various actions are performed, such as actuating the shut-off valve or monitoring the mass airflow sensor for drift (not in VAG applications). Furthermore, the EDC establishes a defined state (e.g., completes EEPROM write cycles) and then deactivates itself via relay 109. After the ignition is switched off, simply listen carefully.

Your option B would also be a great way to cause a fatal accident in the event of a cable break or valve failure.

Hi,
What BSE described, I can observe quite well in my car, since the daytime running lights also get their power from relay 109.
Turn off the ignition, remove the key, and then you can drive approximately 'einundzwan' (presumably a local measurement) before the lights go out.

Best regards,
Rudi