Haldex failure - Audi S3 8L, year 1999

Hello everyone in the forum community,

It seems that a new problem arises every day... many of them only become visible when using VCDS, and it helps many people .

This specifically refers to a pre-facelift Audi S3 8L, with 209 horsepower, manufactured in 1999. The Haldex system is writing an error code to the error memory: "mechanical error - intermittent" (I unfortunately deleted the error memory, so I only have the part number available).

It's certain that the all-wheel drive system isn't working at all - there's no engagement, no locking, no noises, and no warning light!

It only became noticeable when the man, who regularly takes the S3, got into the car again, especially when he had a trailer attached, causing the front wheels to spin.

Wednesday, April 3, 2013, 4:24:27 PM: 16637
VCDS Version: RKS 11.11.5
Data as of: 20130111.


Address 22: All-wheel drive
Label file: RKS\02D-900-554.lbl
Control unit part number: 02D 900 554 B.
Component and/or version: HALDEX LSC ECC 0006.
Encoding:
Operating number:
VCID: 1F4697D39DFD21E0386
No error codes found.

Even the actuator diagnosis doesn't produce any output, which leads me to believe there's a serious defect.

Now, I have a Haldex system including the differential in sight, but it has a slightly different part number than the one that's currently installed -> 02D 525 554 D.

My questions:

Is there anything else I can check, perhaps something mechanical, to help pinpoint the actual cause of the problem?

The oil change hasn't been done yet, as nothing seems to be happening. Could it be that the pre-charge pump is also defective or not being activated?

I hope this issue hasn't already been discussed – I couldn't find anything about it, but maybe someone can help me!

Thank you very much, and best regards.
Alex.

Hello.

I haven't personally had much experience with Haldex all-wheel-drive systems, other than routine maintenance.
However, the cables and connectors of the pump are prone to corrosion. Sometimes, the pumps also seize up, especially if they are used infrequently or with a conservative driving style.

Here's something I found while searching on this topic: "It also helps with '4Motion', since the A3 is actually..."
Golf/VW is


Okay, I understand. Please provide the German text you want me to translate into English. I will only provide the translation.



Greetings Mpire

Okay, I'll check that out, I'll use the measuring device tomorrow... Of course, it's possible that the pump seized up... especially in that driving mode!

I'll take the measurements tomorrow and write them down here.

I will link this thread in the other one as well, if I am allowed to.


Thank you for the prompt reply...it's very valuable when you don't feel like you're alone .

Best regards, Alex.

UPDATE:

Yesterday, I connected the pump's cables and measured the current, which was in the range of 23-27 mA, while the actuator diagnostics were active. I suspect a lack of contact in the brushes or wear.

The pump is receiving onboard voltage, which means the power supply should be fine, but it's not making any noise!

"When I disconnect and reconnect the entire wiring harness of the Haldex unit, a high-frequency squealing or buzzing sound can be heard... probably the control unit (ECU)?"

When selecting the first option in the actuator diagnostics, a clicking sound is heard (like the switching of a solenoid valve, I would say), but strangely, this doesn't happen when "pre-charge pump off" is selected.

"You can't really hear anything when it says 'all-wheel drive engaged' or 'all-wheel drive disengaged'."

By the way, the handbrake switch is probably the faulty component, but it shouldn't trigger any errors during the actuator diagnosis, right?

I also found a guide on how to check the wiring harness, which helped me identify the issue with the faulty handbrake switch. Additionally, I found some inconsistencies regarding the CAN bus lines (the Haldex control unit is sometimes not selectable).

I'm wondering if it makes sense to replace the pump now.

Oil change hasn't been done yet as part of the troubleshooting process --> I left that out for now, because if the pump isn't making any noise, it's probably not related to the oil, right?

The error code in the control unit is back: 01155 - Clutch - mechanical fault, intermittent.

A working Haldex system has been found, as mentioned above, but with some parts having different part numbers!

What should I do next?

Thank you very much for your valued assistance!

Best regards, Alex.

Please check if there's enough oil in it.
I'm not entirely sure if there's a level sensor installed here.
I would start by replacing the faulty handbrake switch.

It is known that Haldex drives sometimes experience contact problems between the control unit and the Haldex unit itself, as the control unit is located directly on the rear axle.

Expand this and take a look at how the contacts appear.

Haldex oil level is okay!

I'll still need to check the control unit... Regarding the pump, I have to say that I didn't find any oil in the connector!

I've now manually applied voltage again, and the pump just doesn't make a sound! The car had also been to the , and he also checked the pump!

The rear wheels are not being driven at all. If the diagnostic tool doesn't show anything wrong with the control unit, I'll just replace the pump!

I've done a little research and also found out that there's a smaller version of the pump available for the all-wheel-drive Seats! Apparently, this smaller pump is supposed to be easier to install and remove... it might be possible to use it.

Does anyone happen to know if the pump can be removed without disassembling any attached components?

Thank you very much, and best regards.
Alex.