sporadischer Ausfall Servo Lenkung Polo 9N3 BLT TDI | Posts 16+

Just came back from the doctor's office.

However, the mass cable at the top was quite heavily corroded with verdigris.
Gesehen habe ich es schon, nur dachte ich das wäre Oberflächlich, nicht das das Ganze Kabel durchgegammelt ist. Schön Peinlich.....

Yes, you're right; it certainly wasn't for free, because I now know a lot more about the car than I did before. That's good and will make future repair work easier for me.

It's really annoying that I didn't notice the persistent damage to the cable.

I'll keep you updated.

The steering wheel appeared crooked, but it wasn't actually misaligned; the locking mechanism of the steering column had engaged, causing the steering wheel to be fixed at an angle.

When I reconnected the battery today and turned on the ignition, it jumped back to the center position. So there's no fault here, just my own mistake. (Embarrassing!) I promise to do better...

Okay, great! Let's start by replacing the ground cable. It might also be a good idea to check the battery positive cable going to the starter and alternator. After that, clear the error codes and check them again after a few days.

Okay, here's my initial assessment after a few days.
Power steering is no longer malfunctioning, and the error memory is clear.

Yesterday, I turned on the low beam headlights and all the high-power consumers (Climatronic and radio) in the dark garage, with the engine running.
The headlights are still flickering when the brakes are applied...

Could it be that the steering angle sensor is still faulty?
I believe the fuse for the servo is an 80A fuse.
If something doesn't fit right, I can imagine that everything could be stalled or put on hold.

I assume it's normal for the headlights to dim slightly when steering with power steering while the car is stationary, as power steering is a significant consumer of electricity.

I'll call the workshop foreman again today. Perhaps there's something about it in his task list (TPL).

Wurschdler wrote:

Yesterday, I turned on the low beam headlights and all the high-power consumers (Climatronic and radio, engine running) in the dark garage. The low beam headlights are still flickering when the brakes are applied... Could it be that the steering angle sensor is still working somehow?

How did you come to that conclusion?

Modern load controllers (LiMas) have a "soft" load acceptance to prevent harsh braking impulses from being transmitted to the drive when consumers are switched on. This results in brief voltage dips with each additional consumer connected.

Ok, und den Spannungseinbruch sieht man dann bei Betätigen der Bremse in der Dunkelheit, wenn man genau hinsieht im Radio Display und im Hauptscheinwerfer Licht. Das ist dann beim Polo 9N3 schlichtweg normal ? ... und ich muss mich mit abfinden....

I'll check tonight to see if the Golf 5 does the same thing...

Once you start paying attention to something, you often become more sensitive to it.

What do you actually mean by "applying hard braking impulses to the drive system"?
Sure, here's the translation:

"About ESP, for example?"

I only remember this from back in the day when I had a 500-watt amplifier in my trunk and huge subwoofer boxes. The car's voltage would even drop when the system was running at full power.
A buffer capacitor provided a solution to that problem...

Wurschdler wrote:

Okay, and the voltage drop can be seen when applying the brakes in the dark, if you look closely at the radio display and the headlight beam. Is this simply normal for a Polo 9N3? ... and I have to accept it...?

Basically, yes.
I can't say whether there might be any additional effects at play with your car, such as increased resistance due to (more) corroded cables, etc.

Quote:

What exactly do you mean by "applying hard braking impulses to the drive system"?

When the electrical load of the vehicle increases, the alternator attempts to supply all the necessary current to avoid discharging the battery. Therefore, when powerful consumers with a high inrush current are activated (e.g., incandescent lamps, electric motors), the required power for the alternator increases sharply = it suddenly pulls strongly on the belt. Unless it has the aforementioned soft load regulation.

Okay, thank you for the explanation.

Hello everyone,

The light machine regulator will be replaced, and then we'll take another look.

It's likely that the light machine regulator also had a way [to do something].

The flickering when pressing the brake pedal is now only minimally visible when the headlight is pointed towards the garage wall, and you have to look very closely and pay close attention to notice it.

If you don't know about it, you won't notice.

The master technician at my dealer also examined the other two Polo 9n3 models (1.2 and 1.4 TDI) that he had in stock. He observed the same phenomenon in those cars as well, if you pay attention to it...

Could a buffer capacitor installed directly after the alternator (between the alternator and the battery) help to improve performance by that last percentage point? Or would I end up causing more problems?

Wurschdler wrote:

Could a buffer capacitor, installed directly after the alternator (between the alternator and the battery), help to improve the last percentage? Or am I just going to break something else...?

In any case, you're more likely to damage your bank account than it will objectively benefit you.
A capacitor can only provide "support" by discharging, but you will never achieve a perfectly smooth voltage this way.

You're probably right; I think I'll just have to accept it.

You already have a large capacitor; that's the battery. What is its age and condition?
I would start by checking the voltage at the regulator/battery and at the affected consumers using a multimeter. There might be more unwanted resistance in other places, or perhaps the regulator voltage is too high, or the battery is too weak.
hg
Herbert.

The battery is as old as the car, so it's from 2007. Now that you mention it, I remember that starting the car took quite a while in the winter. Well, maybe I should invest in a new battery, or perhaps try having the dealer install one as a test if he's willing to do it.

After 4 years, it will probably be time to get a new one anyway...