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.
I've already seen it, but I thought it was just superficial, not that the entire cable is rotten. That's embarrassing.

Yes, you're right, it certainly wasn't for nothing, 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 crooked; the steering wheel lock had engaged, which caused the steering wheel to be fixed at an angle.

When I reconnected the battery today and turned on the ignition, it snapped back into 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. (And it might be a good idea to also check the battery positive cable 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, 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 faulty?
I believe the fuse for the servo is an 80A fuse.
If something doesn't fit, 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 power consumer.

I'll call the workshop foreman again today. Maybe 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, running engine) 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 feature to prevent harsh braking impulses from being transmitted to the drive when loads are switched on. This results in brief voltage dips with each additional load connected.

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. Is this simply normal for the Polo 9N3? ... and I have to accept it.

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

Once you start paying attention, 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 the 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 observed when applying the brakes in the dark, if you look closely at the radio display and the headlight. Is this simply normal for the 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"?

When the electrical load of the vehicle increases, the alternator attempts to supply all the necessary current to prevent the battery from discharging. Therefore, when powerful consumers with a high inrush current are activated (e.g., incandescent lamps, electric motors), the power demand of the alternator increases abruptly, causing it to suddenly pull 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 barely visible, only noticeable if the headlight is pointed directly at the garage wall and you look very closely.

If you don't know, 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 the last percentage of charging? 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), solve the problem for the last percentage?

Or are you more likely to break something? In any case, you're more likely to damage your bank account than it will objectively help.
A capacitor can only "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, which acts like a battery. What is its age and condition?
I would start by checking the voltage at the regulator/battery and at the affected consumers. There might be more unwanted resistance, and it's possible that 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 it took a while to start the car in the winter. Well, maybe I should invest in a new battery, or perhaps I could ask the dealer to install one as a test, if he's willing.

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