Ungewollte Vollbremsung durch ABS | Posts 16+

Guest Free account, no CAN development support

Then, why don't you do as mentioned above?

25-03-2006, 15:23 Subject:

Well, if there's no error code showing up in VCDS, then it won't detect anything, or what exactly should appear in the log?

The polo is still deregistered, so I can't drive it right now

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Guest Free account, no CAN development support

Well, the self-diagnosis feature on the older models wasn't very smart – I'm thinking of my 1997 model – it didn't even detect the two chewed-through lambda sensor wires. I noticed it through the car's behavior, and you could see it in the data blocks, but there was still no error message.

It's definitely worth a try - it doesn't take much time, and if it doesn't work out, you can always keep looking. But since there must be a reason for it, it's important to figure out what that reason is!

25-03-2006, 23:29 Subject:

Quote:

The brake pedal slips all the way down to the floor.

Then the pedal comes back up, and I can continue driving. }

Due to the mechanical connection between the brake booster and the master cylinder (pushrod, pushrod cup), the force can only be transmitted from the pedal and brake booster towards the master cylinder, but not in the reverse direction.
This means that the brake pedal cannot, due to an ABS malfunction, activate itself without the driver's intervention.

If the fault is as you describe, and the pedal is actually pushing itself into the floor without you doing anything, I strongly suspect a faulty brake valve control unit (BKV).

26-03-2006, 3:53 Subject:

Well, but... why would the whole thing then work with the ABS disabled? So, it brakes normally, except that it overbrakes the rear wheels due to the lack of a brake force distribution system.

chris with 1 promille

26-03-2006, 9:30 Subject:

I suspect that the brake lines to the individual wheels are incorrectly connected to the ABS module or the hydroboost unit, and it wasn't initially noticed because a full stop wasn't performed.

26-03-2006, 12:03 Subject:

Quote:

well, but... why would the whole thing then work with the ABS disabled?

So, it brakes normally, except that it overbrakes the rear wheels due to the lack of a brake force distribution system... }

Okay, please explain exactly how the brake pedal is behaving, or who is pressing the brake pedal down.

26-03-2006, 12:55 Subject:

What do you mean? So, when I brake, the brake pedal goes all the way to the floor (like in the test with VAGCOM) and only comes back up when the car comes to a complete stop.

26-03-2006, 20:52 Subject:

Quote:

What do you mean? So, when I brake, the brake pedal (like in the test with VAGCOM) simply goes all the way to the floor and only comes back up when the car comes to a complete stop.

Does that mean the brake pedal stays depressed even after you've taken your foot off it, until the car comes to a complete stop?

26-03-2006, 21:19 Subject:

27-03-2006, 14:45 Subject:

After replacing the ABS sensor on the front left, the same problem persists. I'm starting to run out of ideas.

27-03-2006, 15:05 Subject:

Hi,

Are you absolutely sure the connections are correct? Please see Rainer's last post about it.

Best regards,

Jan.

27-03-2006, 15:26 Subject:

What exactly is wrong with that?

27-03-2006, 15:30 Subject:

Hi,

Rainer actually wrote: "Swapped wires."

Best regards,

Jan.

27-03-2006, 15:33 Subject:

Then it wouldn't just be on the left, but also on the right, would it?

And as far as I know, you can't swap the wires.

Guest Free account, no CAN development support

Oh yes, it's possible - I know an artist who managed to do something similar - it was a 3D project, but it worked

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