Haldex V / implausible values

Good morning, everyone.

I hope you can help me, as the Skoda authorized workshops are unable to do so.

I have a Superb with a 200 horsepower TDI engine and all-wheel drive. Since the 60,000 km service (which included an oil change for the Haldex system), I have noticed unusual noises and increased fuel consumption, and this problem occurs sporadically.

I then purchased VCDS to examine the data from the all-wheel drive control unit in more detail, and that's when I noticed some unusual values regarding the temperatures of the clutch and plates, as well as the speed signal of the pump.

The PWM signal always displays 53%, regardless of the load or blocking level, while the pump's voltage changes. The temperature of the clutch ranges from -224 to over 400 degrees Celsius, while the temperature of the friction plates ranges from over -100 to also over 400 degrees Celsius.

I have attached a VCDS log file. I took a test drive in a Kodiaq 4x4, and the temperatures during that drive were consistently between 20 and 25 degrees Celsius, with no significant fluctuations.

The all-wheel drive system is working, but I have the feeling that it doesn't disengage properly sometimes. Car dealerships are saying there's no fault in the control unit, but it could be the control unit itself, or the pump might be clogged, or the VCDS values might be incorrect, and therefore they don't want to do any further work.

Does anyone have any ideas?
Thank you in advance!

Hello,

Unfortunately, there is no .csv file available for KDataScope, but I have read all the lines of your 26MB PDF.

Please, let's be serious from now on.
Okay, I'm ready. Please provide the German text you want me to translate.

Please post the car's scan data so we can see which control units are involved. The problem you're describing sounds quite unusual to me, like cable damage, power supply issues, or water leakage, etc.

First, check the operating voltage of the control unit to see if it remains stable.

Best regards, Rainer.

Hello and thank you very much for your reply!

I apologize for the data issue from my end; it won't happen again.

Attached is the Autoscan report and the most recent log file. I hope the data is correct!

Thank you again in advance, and have a great weekend!

Best regards,

T. Kehl.

Hello, Thank you

Quote:

You can find SSP333 as a PDF on the web; please check if the structure still corresponds to your vehicle. After the SSP, the implausible temperature sensor would be internal, and the connection of the control unit would essentially be CAN.

I checked, and there are now several generations. The corresponding temperature sensors would be internal.


The operating voltage looks fine, and I don't see any sudden jumps in the temperature readings, even though they seem like fabricated values.

Unfortunately, the control unit or the internal sensor connections would be a very likely source of error.

The question is whether there's a cable connected to the hydraulic pump on your system, and if so, what signals are transmitted through it. Please inspect this cable for signs of damage caused by martens.

Best regards, Rainer.

Good evening, Rainer,

First of all, thank you for your reply. I'm currently on vacation, so I'm only just getting back to you now.

As far as I can tell from my research, the Haldex 5 no longer uses thermostats or temperature sensors; all values are calculated. The version installed appears to be one of the later variants, as the control unit is no longer located on the Haldex itself, but somewhere inside the vehicle. There's only one label leading to the pre-charge pump, but it's encased (it looks like the rodent protection for the engine compartment), and as far as I could see, there was no visible damage.
I have now received an appointment with a Skoda dealer for November 15th. The first Skoda dealer I contacted was simply unmotivated or unable to help me.

I also suspect a faulty cable or control unit, but in a car with so many interconnected systems, the values could be coming from various control units, so it might not necessarily be the Haldex control unit.
"However, it's always good to know what might be causing it for one's own well-being, especially in rare cases, because dealers often lack the experience, and unfortunately sometimes the motivation, to help the customer... after all, they'll probably come back."

I'm now going to focus on enjoying the rest of my vacation and returning home safely.

Thank you very much, and have a pleasant evening.

Good evening.

The vehicle has been at Skoda for two days. According to the diagnostic tool (Odis), the all-wheel-drive coupling is opening and closing as it should. The unusual temperatures, according to the Technical Support Center, are not a major issue as long as everything is functioning correctly. It cost another 130 euros because Skoda doesn't consider it a problem or a warranty case.
I guess I'll have to check the Haldex oil level myself and see if that fixes the strange readings.
It's kind of sobering, I'm not sure whether I should be happy or annoyed.

Thank you very much for your support, and have a pleasant evening.

Thank you for the feedback!

You can try searching for the Haldex control unit using the VAG part number in VCDS via the web.

Possibly, it's a software issue, and you might find an Autoscan with a newer software version somewhere.

You have device 5WA 907 554 P with software version 0724.

Hello Rainer,

Thank you for your reply. According to the workshop, the software needs to be up-to-date, but it's difficult to find the correct information online because these pumps have only been installed since 2021 (and the control unit is no longer located externally on the Haldex system).

For me, the explanation wasn't entirely satisfactory; there has to be a reason for the behavior and increased fuel consumption (in good weather, driving at 100 km/h, it uses between 3.7 and 4.4 liters per 100 km; on a wet road, covering the same distance, it uses 5.5 liters or more).

I performed a logging session of the wheel speed readings. I will upload the data later, and I noticed that there are significant discrepancies, especially on the rear right wheel, with differences of up to 5 km/h. For example, the readings were: front left 84.1, front right 85.2, rear left 85.9, and rear right 80.8.

It can have both negative and positive implications.
I'll measure the sensor later (there's a good YouTube video about it) and check if the voltage is correct. If necessary, I'll also explain the connection to the wet road.

I will report as soon as I can.

Have a great weekend!

Hello,

The Haldex system only distributes power between the front axle and the rear axle.

Between the left and right sides, there is a certain differential, and as long as neither side is being braked by the ABS/ESP (or a wheel is spinning on ice), the wheel speeds can only be very slightly different (in a curve). Or you have a very, very fast driving style.
Even if your car had an electric/mechanical differential lock, in the event of a lock, the wheel speeds on the left and right sides would still have to be equal, as they are rigidly connected.

It's possible that your problem isn't related to the Haldex system at all, but rather that the ABS/ESP system is detecting incorrect wheel speeds and then braking individual wheels, which could also explain the noises you're hearing.

The problem only occurring in the rain suggests a connector or cable issue related to the ABS sensors. Also, don't forget to verschandeln the ABS/ESP sensor rings on the wheel hubs. Magnetic particles (like rust from the brake discs, etc.) can interfere with the ABS sensor signal.

Does a Superb MJ2021 with an electronic locking system and XDS+ have significant differences?

Theo0984 wrote:

Is this a Superb MJ2021, and does it have an electronic locking system and XDS+? Can that explain the significant differences?

When locked, i.e., mechanically connected, the speed is the same on the left and right.

Be careful of marketing terms; my T6 also has an "electronic differential lock," which means that if a wheel starts to spin, the ABS/ESP system brakes that wheel and redirects the power to the other wheel. Unfortunately, it's not implemented optimally, and nothing is mechanically locked.
So, you need to examine in detail whether a locking mechanism is actually installed in the differential, and as I said, if it is locked, there should be absolutely no difference in speed between the wheels.

I just remembered something else: are the wheel bearings okay? If defective, the wheel may wobble, which can naturally also cause the ABS sensor to give incorrect readings.

Best regards, Rainer.

Today I cleaned the two rear sensors. The voltage to each sensor is 10.25 volts, but I couldn't measure the voltage after they were connected.
I then conducted another test drive and calculated the speed differences. As a result, the right rear wheel had a speed approximately 4% lower than the right front wheel (the difference between the left and right front wheels was less than 0.1%), and the difference between the right and left rear wheels was about 1.5%.
I'll check the air pressure again, but 4% shouldn't make that much of a difference.