WFS: What to do when the connection drops during a ride...

Does the car then run out of steam and stop, or does it just keep running? I currently suspect that our WFS (window lift system) in the Passat isn't getting enough power (voltage) during startup, which causes the car to shut down. When it's running, everything is fine, but it's not okay during startup. At first, it only happened when the lights were on, but my father now complains that it's happening even without the lights on.

Best regards, WarLord.

Hi,

Okay, I can only speak from my experience with my old Polo 6N. It once had a similar issue where it would briefly start and then immediately shut off. In that case, the reading head in the ignition switch was faulty... but I don't know if that applies to the Passat generation as well.

Hi,

As far as I can dimly recall, the WFS is only queried shortly after startup.
It is not advisable to query the Wheel Friction System (WFS) while driving because vehicle vibrations could cause the sensor to produce invalid signals, potentially causing the car to stop unexpectedly. The WFS must be designed in such a way that failure during operation is impossible; otherwise, this design will not receive approval (which means no querying while driving).

Could it perhaps be the Wunder Relay 109 instead?

joergs wrote:

könnte doch aber auch das wunderrelais 109 sein oder ?

... which also serves as a kind of unintended Web Feature Service .


Sure, here's the translation:

"Anything else?"

The WFS coils (in the ignition switch) seem to be subject to wear and tear. Lately, I've been hearing more and more people who had to replace the reading coils in their (older) vehicles (not just VAG products).

Okay, I'm ruling out relay 109 because the motor runs for about 1 second after starting and then shuts off. I once had a similar result when I was experimenting and, just for fun, pulled a plug from an unknown device. *g* The reading coil also seems interesting to me, since the car is already about 7 years old and approaching 8 years. Is it possible to replace the reading coil separately from the lock?

Best regards, WarLord.

Bertil wrote:

The WFS coils (in the ignition switch) seem to be subject to wear. I've been hearing more and more people lately who had to replace the reading coils in their (older) vehicles (not just VAG products).

Hi Bertil,

A coil is one of the most "non-mechanical" things there are – what could possibly wear out?

A permanent magnet that could weaken over time is not a factor in the WFS, as far as I know.

I can only imagine that the cause might be...
a) Corrosion of the coil connector contacts on the WFS control unit.
b) Instability in the coil circuit due to vibration-induced cable breaks.

At least in case a), installing a new coil would once again be the usual way to waste money instead of thinking things through + checking the connectors.