Ungewollte Vollbremsung durch ABS | Posts 32+

Okay... but... why would it only be on the left front if it were swapped, and not also on the right?

We'll probably be explained why this is the case later - I was just pointing out the general idea that the data might be incorrect. I haven't quite grasped the underlying reason yet, but if Rainer writes something like that, there's probably a good reason for it. Let's wait and see.

Assuming there are only two swapped items - for example, the front and rear ones - that's good.

ABS engages the brakes, the wheels are braked - now it detects that the front right wheel is free, and releases pressure - but due to a reversed line, the front left wheel (VL) rotates freely - the ABS sensor reports 'Hey, the front left wheel is rotating freely, are you stupid?' - then the ABS system says 'Full pressure on the front left wheel, which is actually the front right wheel...'

I can imagine that the ABS might be affected by the wind, and it would likely be quite difficult to steer properly during a critical braking maneuver with steering input to avoid something .

'Therefore, I believe that swapping them is impossible. Firstly, a swap should be impossible due to the different diameters of the nipples. Secondly, the ABS control unit should recognize this as an error and turn on the warning light (due to a discrepancy in the control parameters).'
I think the problem is more likely to be in the valve block, which, as far as I can see, is separate from the control unit and the pump. Could that be the case?

Quote:

but if Rainer writes something like that, there's a reason for it

.
This time, I was just guessing . I actually thought the entire valve block with the pump had already been replaced, but the first post only mentions the pump... so it might be the case.

Best regards, Rainer.

Okay, so the pump (which I consider to be a valve block) and the control unit have been replaced, and that's basically all there is to it.

Okay, I'm retracting everything I said before and claiming the opposite. I've looked into it, and it seems that it is indeed possible to swap them out, as it appears that 'Einsraupnippel' with the same diameter were used here. Therefore, it is possible to interchange them.
The instructions for actuator diagnostics state that this procedure should be performed by two people. The displayed statuses (locked, free) must be checked. The pedal *must* show some give when the inlet valve and outlet valve are in the UBatt state, and the wheel must be able to rotate freely. If this is not the case, the lines may be reversed, or there may be a fault in the valve block.

In short, it's very likely a problem with the brake lines.

So... we just performed an actuator diagnosis.

Has anything been swapped around by chance, because when the car is lifted, the wheels seem to be aligned correctly during the test.

However, the front wheel is locked, while the rear wheel is free. On the right side, it's the opposite: the wheel is free, and the lock is engaged. So, it's the correct way around.

Now the idea is to swap the ABS module from the left side to the right side, and vice versa. If the module is defective, the error should then appear on the side where the module was moved. However, the probability of both ABS modules being defective and having the exact same issue is very low.

If that's not the case, then it must be due to the wiring, although that raises the question of why it works without ABS.

Frustrated...
Chris.

Okay, so it works like this! "Free" means the wheel is not blocked, and "locked" means it is blocked. However, it's exactly the opposite for the left wheel. And on the right side, it's correct, so "free" means it's free, and with "locked," it won't turn.

ABS Hydraulic Pump (V64) => works without issues.

front left inlet valve: 0 volts
outlet valve: 0 volts
wheel: locked

front left inlet valve: VBatt: outlet valve: 0 volts: wheel: locked.

front left inlet valve: VBatt: outlet valve: VBatt: wheel: Free => The pedal simply goes down to the bottom plate AND the wheel cannot be turned!

front left inlet valve: Vat: outlet valve: 0 volts: wheel: Free.

front left inlet valve: 0 volts; outlet valve: 0 volts; wheel: locked => Pedal goes back up AND the wheel can turn again

Well, just like you, I'm also completely out of ideas .

Quote:

If that's not the case, it must be due to the wiring, although that raises the question of why it works without ABS.

Perhaps it's because the valves are behaving in a "neutral" way? The brakes are supposed to work even without ABS.
Have you finally checked the lines, or not?

Could you please explain what exactly was modified and in what order? Did the vehicle previously have ABS, or was it retrofitted? How was all of the wiring done?
Could it be that the wiring of the ABS connector is incorrect?
Currently, the wheel is rotating in the opposite direction, so there must be a reversing component somewhere. It also seems unlikely that two control units and two hydraulic units would all be causing the same error.

basti188 wrote:

Could you explain to me what exactly was modified and in what order? Did the vehicle previously have ABS, or was it retrofitted later? How was all of that wiring done? Could it be that the wiring of the ABS connector is incorrect? Currently, the wheel is behaving in reverse, so there must be a reversing mechanism somewhere. It also can't be the case that two control units and two hydraulic units are causing the same error.

"It didn't have ABS before, but it has the original wiring harness, so there's practically nothing that could be wired incorrectly because nothing has been modified. If the ABS connector is wrong, shouldn't there be an error code stored somewhere?"

2 control units = same error: I agree with you on that.

Hi everyone,

I'm having the same problem with my ABS (ATE 1j0 907 379), which is installed in my Polo GTI, manufactured in 1998/1999. The ABS is bringing the car to a complete stop.

Here's the story of what happened. After I had new tires installed (about 2 weeks later), the ABS light suddenly came on. I went to ATU to have the error codes read (it's cheaper there). The error codes indicated that the hydraulic pump was reporting an intermittent fault. ATU cleared the error, but it reappeared after a short drive. They couldn't do anything else and referred me to VW.
Dann hab ich den wagen bei VW checken lassen und die haben direkt eine Diagnose an der ABS einheit gemacht. Dort lies sich dann (angeblich) keine Stellglieddiagnose durch führen. Pumpe lies sich aber (durch überbrücken) ansteuern. Erklärung VW ABS Steuergerät defekt. Da dies nur in Verbindung mit der Pumpe getauscht werden könne belief sich der Kostenvoranschlag auf ca. 1200€ mit einbau... Da mir das ein wenig viel vorkam hab ich das erstmal nichtmachen lassen. Und da ich gelernter Informationselektroniker bin hab ich mir das Steuergerät rausgebaut und die Platine auf kalte bzw. oxidierte Lötstellen sowie Platinen brüche untersucht. War aber nichts festzustellen. Nach dem ich alles wieder verbaut hatte und die Foren durch wühlt hatte, wurde mir dazu geraten (das das Steuergerät) vielleicht nicht genügend Spannung bekommt, dass X-Relais zutauschen, was die Verbraucher im Zündmöment abschaltet wozu auch das ABS gehört. Also Das Relais getauscht und siehe da, die Lämpchen gingen aus. Nach einer Vollbremsung blieb allerdings das Pedal unten (nachdem ich den Fuss runtergenommen habe) und kam erst nach dem Stillstand des Wagens zurück. Mein Tuner (ehm. Meister bei VW) guckte mich mit grossen augen an und sagte mir, dass das Lebensgefährlich sei, aber hatte auch keinen weiteren rat für mich... Da"Eventually, I disconnected the fuse for the ABS system, so that normal braking without ABS is possible."
Also bin ich nochmals mit diesem Fehler in eine andere VW werkstatt gefahren um diesen Fehler checken zulassen. Nach test fahrt mit deren Meister und auslesen des Speichers stand nicht mehr die Pump, soderen das Steuergeärt an sich im Speicher ( ebenfalls sporadisch und messwerte ausserhalb der tolleranzt). Aber ich geb ja nicht soviel auf die Fuscher von VW . Also hab ich mir einen Diagnosestecker besorgt und mich dort nochmals hintergeklemmt. Im Speicher standen beide Radsensoren und nix von Pumpe oder Steuergerät. Also hab ich die Sensoren sammt Drehzahlfühler vorne links und rechts getauscht. Allerdings war bei der Stellglieddiagnose es so das das Pedal bei dem Rad vorne links bis zum Bodenblech durch sackte. Also hab ich auf Luft in der ABS-Pumpe oder dem System getippt und habe (mit anleitung von VAGCOM) die Bremse entlüftet (mehrmals). Nach anschliessender Testfahrt war es nun so das bei Bremsungen von 30-40 km/h das ABS normal reagierte, aber bei bremsungen von 40-70 etc. das bremspedal zwar direkt wieder zurück kam, aber das ABS trozdem bis zum kompletten stand des Wagens runter gebremmst hat. I suspect either that the control unit is faulty or that there is still air in the pump, and I might need to have it professionally bled by a VW technician.
I'm just very surprised that the error is still present on ChrisdaKing's device even after replacing the unit, and I really don't want to have to pay a lot to replace my own block...

Maybe someone still has a tip or an idea.

P.S.: I believe it's impossible to swap the cables, as they are so tightly secured that you would have to force them into a different position.

Best regards, Marc.

"How cool! I'm not alone anymore! Please send me your ICQ number via private message or something like that ."

I think it's really crazy that the same thing is on the front left side for you too!

mein ABS geht wieder auf einen Tip von meinem Superhelden "MarcM" !!!! THANK YOU!

But it's really embarrassing to bother you with this, I never thought I'd have such a trivial error... oh man .

http://www.polo6n-tuning.de/abs.jpg

The brake line for the wheel was connected to the fitting for the handbrake booster... lol! (The top right and bottom right were swapped.)

Okay, actuator diagnosis performed: no errors found, everything is okay!

Sorry and thank you for the help.

Chris *is embarrassed*.

Hi,

Well... Rainer was completely right about that, pretty much from the very beginning!

Best regards,

Jan.