Traction Contol activates over bumps:

[Buksie]

Traction Contol activates over speed bumps while accelerating at low speed. (App. 25-35km/h)

VW Transporter 4motion T6.1 2022 with 15000km’s since new.
This is worrying me that the traction control is activating unwantedly or spontaneously by braking one or both the rear wheels. Normally when the traction control activates the system will reduce power, but not in this case! The bus accelerates while the traction control “noises” can be heard from the rear of the bus and the traction control light flashes on instrument panel.
This happens while traveling in a straight line and crossing the speed bumps at a right angle(90deg) with marginal acceleration. This only lsat for a second but happening between 3 to 6 times per day.

More recently my left rear CV/drive shaft broke splines and was replaced by VW. However, the brand new CV and booths lasted only 1400km’s in 10days when a similar breakage happened, but this time the damage was on the differential side of the same CV. So VW is now replacing the rear differential and CV. “Much appreciated”.

My line of thinking:
Our residential area is filled with speed bumps. When crossing over bumps on slight uphill one needs to accelerate, causing the traction control to activate. The fact that the enjin or power to drive train is NOT automatically reduced should/can cause unwanted strain and stresses to parts of the drive train. The weakest points will have premature failure.

This never happened with my previous 4Motion Transporter!

I think the spontaneous traction control activation weakens the splines (and everything els in the drive train). Something is bound to break!

Have you experienced or heard of this?
Can it be a faulty abs/asc sensor?

Hope to find some help or opinions, pls?


IMPORTANT:
VW South Africa and the VW dealer is of great assistance by keeping me informed and providing alternative means of transportation.

 

[mmi]

What size of tyres you have - all identical?

VW Transporter 4motion T6.1 2022

Manual or DSG?
What's the engine code (on sticker under dash by steering column)?

 

[Phil_j89]

The tyres look close, if not touching the inner wheel arch in that photo.
What size wheels / tyres are fitted?

 

[Buksie]

Hey guys, valid comments
All 5 tyres are exactly the same.
And I do a 5wheel rotation including the spare wheel. This specifically to have all tyres at the same diameter.

The tyres doest touch!

 

[Oceanis]

At parking speeds there is a function that will slam on the brakes if the vehicle thinks you are going to hit something, this happens with large kerbs and other obstructions .... then there is front assist, which will also apply the brakes if it thinks you are going to hit something. I have come accross one speed bump in the U.K. where this behaviour was repeatable. There was a very unpleasant graunching noise and speed reduction as I approached the speed bump - didn't notice what was displayed on the dash though.

The VW handbook says ....

Switching off Front Assist

Front Assist is not suitable for use in the following situations due to the limitations of the system and must be switched off → Switching off Front Assist:

• If the vehicle is utilised in a capacity beyond usage on public roads, e.g. offroad or racing tracks.
• If the vehicle is being towed or is loaded onto another vehicle.
• If the radar sensor is covered by any auxiliary equipment, e.g. auxiliary headlights.
• If the radar sensor is faulty.
• After external force on the radar sensor, e.g. after a rear-end collision.
• In the event of multiple unwanted interventions.

... my guess is that your speed bumps are big enough to fall between "off-road" and "multiple unwanted interventions". I'd try turning off front assist.

 

[Buksie]

At parking speeds there is a function that will slam on the brakes if the vehicle thinks you are going to hit something, this happens with large kerbs and other obstructions .... then there is front assist, which will also apply the brakes if it thinks you are going to hit something. I have come accross one speed bump in the U.K. where this behaviour was repeatable. There was a very unpleasant graunching noise and speed reduction as I approached the speed bump - didn't notice what was displayed on the dash though.

The VW handbook says ....



... my guess is that your speed bumps are big enough to fall between "off-road" and "multiple unwanted interventions". I'd try turning off front assist.

View attachment 210606

Thank you, but no, we have tested the slow/parking speed emergency brakes and they work very well resulting in a sudden stop! They don’t work at high speed such as 25km/h

 

[Buksie]

The tyres look close, if not touching the inner wheel arch in that photo.
What size wheels / tyres are fitted?

The tyres definitely don’t touch the wheel arches and definitely not when driving straight. Also my Traction Controll light is illuminated for the second it happens. And the sound is clearly from the rear. The vehicle does not break or experience any kind of slowing down or reduction of power… the acceleration continues as requested BUT the traction control is breaking a wheel at the same time.

There is no doubt that it is the traction control activation causing the sound.

The real question is: because the power is not removed from the drive train while the traction control is breaking a wheel, CAN THIS CAUSE THE CV SPLINES AND GEARBOX TO FAIL?

 

[Buksie]

The tyres look close, if not touching the inner wheel arch in that photo.
What size wheels / tyres are fitted?

235/65 R17 AT GoodYears
This Kombi has the factory ordered/fitted Rough Road Suspension resulting in a +-20mm lift
They

 

[Buksie]

What size of tyres you have - all identical?


Manual or DSG?
What's the engine code (on sticker under dash by steering column)?

DSG 7speed

Will the info in the photo below be of any help?

 

[Oceanis]

Thank you, but no, we have tested the slow/parking speed emergency brakes and they work very well resulting in a sudden stop! They don’t work at high speed such as 25km/h

Up to 30km/h Front Assist applies full braking, and can detect moving or stationary objects.

... mine exhibits exactly this behaviour, triggering the brakes for large speed bumps.

Check this out too.

Volkswagens Needlessly Brake on Their Own Due to Defects in the Front Assist Technology

VW's collision avoidance technology is detecting objects that don't exist. When that happens it slams on the brakes and ends up putting unsuspecting occupants in harm's way. A lawsuit wants the automaker to do more than simply suggest that owners turn the premium feature off.

www.vwproblems.com

 

[Buksie]

Up to 30km/h Front Assist applies full braking, and can detect moving or stationary objects.

... mine exhibits exactly this behaviour, triggering the brakes for large speed bumps.

Check this out too.

Volkswagens Needlessly Brake on Their Own Due to Defects in the Front Assist Technology

VW's collision avoidance technology is detecting objects that don't exist. When that happens it slams on the brakes and ends up putting unsuspecting occupants in harm's way. A lawsuit wants the automaker to do more than simply suggest that owners turn the premium feature off.

www.vwproblems.com

Thanks, but my Kombi is only fitted with the Park Assist = full breaks (and it works

My Kombi is not equipped with Front Assist technology.

 

[Buksie]

DSG 7speed

Will the info in the photo below be of any help?
View attachment 210680

MMI, could you find anything on my engine number?

 

[mmi]

MMI, could you find anything on my engine number?

Oh, apologies not explaining. I had a thought that the issue possibly would have been related with strange (IMO) behaviour of 4Motion described below

[T6_measured] A Comparison of 4Motion traction modes

4Motion Adaptation channel - MAS06098-Acoustic measure wiring logic STANDARD / INCREASED TRACTION / REDUCED NOISES T6/T6.1 Haldex clutch has an adaptation channel which presumably changes clutch clamping behaviour. The channel can be tweaked with various tools. Conditions for the measurements...

www.t6forum.com

[T6_measured] 4motion Abnormality And Subsequent Failure

Reference documents: VW Self Study Programme SSP 561 –The T6 2016, which in chapter Power transmission (p.26) for details on 4Motion control logic refers to: VW Self Study Programme 414 – 4MOTION with 4WD coupling generation IV. The document can be read and downloaded at SSP 414 Spesifics...

www.t6forum.com

However, the strange behaviour - full lock between front and rear axles - even foot off the throttle - has not been an issue with CXEB/CXEC engines. (your engine number CXE....) Also the strange behaviour with vans with DSG happens only on gears 5-7.

 

[Buksie]

Oh, apologies not explaining. I had a thought that the issue possibly would have been related with strange (IMO) behaviour of 4Motion described below

[T6_measured] A Comparison of 4Motion traction modes

4Motion Adaptation channel - MAS06098-Acoustic measure wiring logic STANDARD / INCREASED TRACTION / REDUCED NOISES T6/T6.1 Haldex clutch has an adaptation channel which presumably changes clutch clamping behaviour. The channel can be tweaked with various tools. Conditions for the measurements...

www.t6forum.com

[T6_measured] 4motion Abnormality And Subsequent Failure

Reference documents: VW Self Study Programme SSP 561 –The T6 2016, which in chapter Power transmission (p.26) for details on 4Motion control logic refers to: VW Self Study Programme 414 – 4MOTION with 4WD coupling generation IV. The document can be read and downloaded at SSP 414 Spesifics...

www.t6forum.com

However, the strange behaviour - full lock between front and rear axles - even foot off the throttle - has not been an issue with CXEB/CXEC engines. (your engine number CXE....) Also the strange behaviour with vans with DSG happens only on gears 5-7.

Wow, tx for the above.
However my engine is the CXE... and i dont see a correspondence. Or what do i miss?

Mine sounds like traction control activating and only at very slow speeds. Instead of traction control activating, can it be ABS or anything else?

 

[mmi]

However my engine is the CXE... and i dont see a correspondence. Or what do i miss?

I'm fairly confident the full engine code is either CXEB or CXEC - the last letter (B, C) is just hardware revision. Please find configuration sticker under dash, in driver's footwell - the full engine code is printed there.

Mine sounds like traction control activating and only at very slow speeds. Instead of traction control activating, can it be ABS or anything else?

The traction control is triggered by ABS. It would be easy to track or even pinpoint wherefrom the trigger comes - with a proper diagnostics tool - e.g. VCDS cable and software - VCDS with HEX-V2 USB Interface - Unlimited - Hex Diagnostics

By monitoring traction control trigger and watching what happens at the same time in the ABS. Chafed wire perhaps?
The ABS has about 230 data values to monitor, the most obvious related to traction control are:

IDE02986-IDE04431 Indicator lamps-ASR and ESP indicator lamp​

​

IDE04425-IDE00920 Left front ABS wheel speed sensor-Front left wheel speed​

IDE04426-IDE00921 Right front ABS wheel speed sensor-Wheel speed: right front​

IDE04427-IDE00922 Left rear ABS wheel speed sensor-Left rear wheel speed​

IDE04428-IDE00923 Right rear ABS wheel speed sensor-Right rear wheel speed​

​

IDE04422-IDE04450 Brake system sensor-Brake pressure sensor 1​

​

IDE04443-IDE02241 Slip control system sensor-Lateral acceleration sensor 1​

IDE04443-IDE02538 Slip control system sensor-Longitude Acceleration Sensor​

IDE04443-IDE04429 Slip control system sensor-Lateral acceleration sensor 1: offset​

IDE04443-IDE04430 Slip control system sensor-Longitudinal acceleration sensor: offset​

IDE04443-IDE04449 Slip control system sensor-Rotation rate sensor 1: Z-axis​

IDE04443-IDE04460 Slip control system sensor-Steering angle sensor: offset straight line running​

IDE04443-MAS00815 Slip control system sensor-Steering angle sensor​

IDE04446-IDE01599 Hill descent control-Incline​

​

The first one would pinpoint the exact moment of traction control activation, I would expect to see something drastic in other data values.