[tilt]

2015 Jetta TDI DSG Highline

This car has hill-hold assist which I believe is supposed to hold the car on an upward incline for about 3 seconds.

The issue is, it works intermittently. Sometimes it works perfectly, sometimes the car rolls back a little. I have been complaining about this since August 2018.

The frustrating point in my case is that it never seems to misbehave when trying to replicate the issue with VW service people on board - it occurs only when they’re not there in the car.

Well, actually it did happen a couple of times with them on board, but they refuse to accept that they observed it.

They also tell me that “it only rolled back very slightly, and that’s how it’s supposed to behave”; and “hill-hold only works when you shift from neutral to Drive, and not when coming to a complete stop without shifting to Neutral”.

To their credit, the VW service centre did try speaking with VW India’s senior tech folks at the factory; but the tech folks say that unless there is a fault code there is nothing they can do. And there is no fault code!

I did try to shoot a video of when this happens, but the video only shows a slight roll-back and they’re unwilling to accept that the video shows any rollback.

Any ideas on what else I could do to try and get them to do some trouble-shooting without fault codes?

The car is completely stock, no mods of any kind anywhere other than using a spare fuse to connect a dash cam.

Thank you and cheers

[ajmat]

My take is

1: The sensor which detects an incline is kaput or
2: The motors / holding device which grips the brake disks might have a connectivity issue or the motor is failing

Am not sure re: point 2 on how the Hill Holder works. I applied the logic of electric handbrakes, the motors within these which bite the disc usually fail after lots of mud and water corrodes and wears the motor out. Happens to a lot of Passats.

[mpp19]

Seems to be a typical VW dealer's behaviour, unfortunately, too much reliance on the software does not help either.

I had some issue (not similar) with my Vento, it used to make some noise (not always but at times) when running on 2nd or 3rd gear and I had to take it to the service centre for 3-4 times. Each time they would cut me down citing no warnings/fault codes displayed or they could not hear/notice any noise in their test drives, but I didn't give up.

Finally, it was thanks to a wonderful service person, who in one of the test drives agreed that there is some noise made and it turned out to be some fault with the front passenger seat positioning. And then it was an easy fix.

So, don't give up and keep persisting and I am surprised how can they deny the video evidence. Have you tried/tested in one of their test-drive cars to see if something similar happens?

[tilt]

Originally Posted by ajmat

My take is

1: The sensor which detects an incline is kaput or
2: The motors / holding device which grips the brake disks might have a connectivity issue or the motor is failing

Am not sure re: point 2 on how the Hill Holder works. I applied the logic of electric handbrakes, the motors within these which bite the disc usually fail after lots of mud and water corrodes and wears the motor out. Happens to a lot of Passats.

Thank you Ajmat. I shall ask them to check the motor. Hill hold apparently applies the rear brakes for 3 seconds to give the driver enough time to move the foot from the brake to the accelerator. It is somehow part of the ABS system in the car. I think what it means that it is part of the ABS portion of the software.

BTW, if the incline sensor is kaput, I am guessing it should show a fault code, no? The main problem here is that there are no fault codes at all!

They did update some software now after I c0omplained, but that has to deal with the DSG portion and not the ABS portion.

According to them, if they have to replace the ABS system it would cost them 1.5 lakhs; and I am of the opinion that they do not want to eat this cost under warranty. BTW, this is the Rajaji Nagar service centre I am talking about.

Originally Posted by mpp19

Seems to be a typical VW dealer's behaviour, unfortunately, too much reliance on the software does not help either.

I had some issue (not similar) with my Vento, it used to make some noise (not always but at times) when running on 2nd or 3rd gear and I had to take it to the service centre for 3-4 times. Each time they would cut me down citing no warnings/fault codes displayed or they could not hear/notice any noise in their test drives, but I didn't give up.

Finally, it was thanks to a wonderful service person, who in one of the test drives agreed that there is some noise made and it turned out to be some fault with the front passenger seat positioning. And then it was an easy fix.

So, don't give up and keep persisting and I am surprised how can they deny the video evidence. Have you tried/tested in one of their test-drive cars to see if something similar happens?

Thanks mpp19. I am not giving up. The video evidence is not that obvious, you need to look carefully to spot the roll-back.


I just got a call from Rajaji Nagar saying that a senior tech from Pune is visiting next week and that they would like me to bring the car over to show the tech and see if the issue can be replicated. Keeping my fingers crossed and praying fervently that the problem does crop up!

Thanks again and cheers

[Flyer]

Originally Posted by tilt

2015 Jetta TDI DSG Highline
This car has hill-hold assist which I believe is supposed to hold the car on an upward incline for about 3 seconds.
The issue is, it works intermittently. Sometimes it works perfectly, sometimes the car rolls back a little. I have been complaining about this since August 2018.
Any ideas on what else I could do to try and get them to do some trouble-shooting without fault codes?
The car is completely stock, no mods of any kind anywhere other than using a spare fuse to connect a dash cam.
Thank you and cheers

It might be a problem with the ABS sensor.

Im encountering the same problem in my A3. But my vehicle showed error code for ABS. The SA said Hill Hold & Brake Assist wont work if any of the ABS sensor is not working properly. After checking, they found one of the four ABS sensors faulty and they have agreed to replace under warranty. One sensor costs around 15k rupees. So try checking if the ABS sensors in your car are in proper working condition.

I have been complaining about this since August 2018.

The frustrating point in my case is that it never seems to misbehave when trying to replicate the issue with VW service people on board - it occurs only when they’re not there in the car.

Well, actually it did happen a couple of times with them on board, but they refuse to accept that they observed it.

I also encountered this first in 2018 July. But then car will show the error intermittently only, and the error wouldn't appear while at service center. So the technicians refused to accept that there is actually any fault. Quoting my post then on TBHP then on the same issue below. After almost a year they have finally accepted to change the sensor under warranty.

Originally Posted by Flyer

- ESC/ABS fault warning message appeared twice on MID.
This issue is due to the fault with one or more of the four sensors for ABS. The SA mentioned that many A3 & Q3's are now coming in with this problem since the heavy monsoon started in Kerala. The problem occurs due to moisture and dirt getting accumulated on the sensors. The SA assured to replace the faulty sensor under warranty.

But with my car they were not able to find the faulty sensor since the error is not always present. They cleaned all four sensors and did some simulation to find the faulty sensor but in vain.

They said they need the car with them for an uncertain period (that is till the fault reappears) to find and replace the faulty sensor. But I refused to give the car as I need it in the coming weeks. The SA confirmed to me that there is no safety issue and it's totally safe to use the car now and I can bring back the car if the issue appears again.

Today morning it reappeared. The MID showed two errors.
1. ESC / ABS fault.
2. Hill hold assist unavailable.

It appears for few minutes only and then disappears. It doesn't come when the car is in the workshop. Does any other A3/Q3 owners face similar issues?

[tilt]

Thank you, Flyer. They said they had checked the sensors and that they could find nothing wrong with them (just like in your case); and refused to change anything citing the high cost to replace.

Like I said above, some tech from Pune is expected to visit this week. I hope I get to demonstrate the issue to him.

I shall keep you folks posted as to what happens.

Thanks and cheers

[tilt]

OK, update:

I showed the car to the VW tech who was visiting (they call them Flying Doctor BTW). And I was finally able to replicate the issue in their presence.

They refuse to accept that this is a problem, they say it is expected behaviour. To prove me wrong they took out a Passat (that has Auto-hold - which is different from Hill Hold in function) and showed me that when Auto-Hold is turned off, the car does roll back.

When Auto-Hold is turned on, of course the car does not roll back; nor does it roll forward - which is exactly how auto-hold is supposed to work, as opposed to hill hold which only works on an incline.

My contention was that in cars equipped with Auto-Hold there is no separate Hill-Hold function at all, and that Auto-Hold serves both purposes, but they disagreed with me.

I asked them to take out any other car with a DSG without auto-hold, say a GT TSI or a Vento DSG or an Ameo DSG. Their contention is that in a Vento the DSG is programmed differently and that it will not roll back, but in a Jetta it is not a function of the DSG, but rather ABS, and therefore Jettas will roll back.

This is getting to be ridiculous. I am getting the (mistaken maybe?) impression that they are flat out not interested in undertaking any investigation that might lead to an expensive warranty replacement and that they are doing everything they can to deny that the issue exists.

Their claim again is that if there were a problem with any component, a full code will show up, and that if there is no fault code, there is no problem at all.

I finally managed to convince them to say that they will discuss it and see what else they can look into in the absence of fault codes and see if they can come up with any ideas, and off so, they will get back to me.

Now that brings me to a favour I am asking of TBHPians - any of you who owns a Jetta Highline DSG, I need you folks to do the following tests for me and report back here:

1. While in Drive, bring the car to a complete halt on an upward incline, release the brake, and see if the car rolls back (within three seconds). Do not shift into Neutral for this test, leave it in Drive, brake to a complete stop, release the brake and test.

2. Repeat the same test, but this time after coming to a halt, shift to Neutral for a few seconds with the brakes on, then shift back into Drive and release the brake and see if the car stays for three seconds or if it starts to move back immediately.

I request you to please do this test a few times if you can, and please, please, do report back here. I would like to use this thread here to show VW India that nobody else with the exact same car has this issue and that it is only my car that has this issue and that they do need to look deeper into it rather than just rely on non-existent fault codes.


Oh, and BTW, they also claimed that since the GT TSi and Vento and Ameos were Dry-Clutch and mine was a wet-clutch, they cannot use those cars to compare. My contention was that hill-hold is a function of the ABS subsystems nd NOT the transmission subsystem, so it should not make a difference - they refused to accept this.

Thank you and cheers

[shashank.nk]

I have the exact same model with DSG. Will try what you've suggested and post results once I get home.

[GoBlue]

Originally Posted by tilt

Now that brings me to a favour I am asking of TBHPians - any of you who owns a Jetta Highline DSG, I need you folks to do the following tests for me and report back here:

Sharing observations based on a Polo GT TSI driven for 48k+ kilometers.

Originally Posted by tilt

1. While in Drive, bring the car to a complete halt on an upward incline, release the brake, and see if the car rolls back (within three seconds). Do not shift into Neutral for this test, leave it in Drive, brake to a complete stop, release the brake and test.

If the brake is applied 100%, the car does not roll back after releasing the brake (whilst the accelerator pedal is not applied).

However, in my observation if the brake pressure is not applied 100%, the car does roll back slightly after releasing the brake pedal.

[Tanveer_2558]

Originally Posted by tilt

Now that brings me to a favour I am asking of TBHPians - any of you who owns a Jetta Highline DSG, I need you folks to do the following tests for me and report back here:

VW service centre at its best!

Jetta's hill hold is the most sensitive one that i have come across, Jab the brake pedal lightly even on the slightest of incline the car will hold itself for 3 seconds or simply keep ur foot very slightly on the brake pedal (As if your feet is resting on the brake pedal) And the car will hold itself till you don't take off your feet from the brake pedal. Infact its that sensitive that initially when i had bought the car, While taking few speed breakers very slowly once your front two wheels are on the breakers and your very slow the car would engage auto hold if your pressing the brake pedal slightly.

Worked like a charm in my MT jetta Highline too and yes the car should NOT roll back even the slightest !

[audioholic]

Originally Posted by tilt

They refuse to accept that this is a problem, they say it is expected behaviour. To prove me wrong they took out a Passat (that has Auto-hold - which is different from Hill Hold in function) and showed me that when Auto-Hold is turned off, the car does roll back.

When Auto-Hold is turned on, of course the car does not roll back; nor does it roll forward - which is exactly how auto-hold is supposed to work, as opposed to hill hold which only works on an incline.

As far as I am aware, the two technologies are slightly different in how they are implemented. In case of Hill Hold, you are required to press the brake pedal hard and that pressure is held by the ABS/ESP module for a while before it is released. Hence, you should ideally be pushing the brake pedal hard for the car to hold it after you release the pedal. Do check if the car rolls back even after you press the brake pedal hard. If thats the case, then check if the roll back is intense or gradual. Intense rollback will mean the pressure was never held, while a gradual rollback will mean the ABS/ESP module will have a leaky/malfunctioning solenoid valve. If its the latter, then it isnt a good thing. But if its the former, then it would be an external factor and the troubleshooting process will be valid.

Typically it should work for a slight press of the brake pedal also but that press must be hard enough for the vehicle to come to a standstill manually too. If it works fine with a hard push of the pedal, the issue can be something as simple as improper bleeding of brakes. Please get it done if that hasnt been done yet. Air in the brake lines will make the brake response spongy. Especially if the air is downstream of the module, even though the module can hold the pressure, air which is compressible will play havoc and wont engage the brakes properly. Like the name goes, its a hill hold mechanism and cannot build its own pressure to keep the car standstill. Whereas, AFAIK the auto hold uses the electronic park brakes which can be engaged and disengaged automatically. But the usual hill hold is a mostly mechanical tech with very little electronics or software playing around.

[shashank.nk]

Originally Posted by tilt

I request you to please do this test a few times if you can, and please, please, do report back here.

I tried this on my car and it works as it should.

1. While in Drive, bring the car to a complete halt on an upward incline, release the brake, and see if the car rolls back (within three seconds). Do not shift into Neutral for this test, leave it in Drive, brake to a complete stop, release the brake and test.

2. Repeat the same test, but this time after coming to a halt, shift to Neutral for a few seconds with the brakes on, then shift back into Drive and release the brake and see if the car stays for three seconds or if it starts to move back immediately.

In the three times I tried, whether I left it in D with my foot on the brake pedal, or shifted to N before coming back to D, the car stood still even when I took my foot off the brake pedal and only began moving ahead around the 2.5 second mark.

The second time, the car was barely at crawling speeds and on an incline,so a slight tap was all it took to bring it to a stop, didn't notice any roll back despite not having my foot on the brake pedal and not pressing it down as much as say I would in a Swift.

In both cases the car moved forward, and didn't roll back by even a mm.

Once i'm a little free,I'd be glad to accompany you and show it to them as many times as may be needed until they acknowledge the issue. I don't see any reason for yours to behave differently considering its the same year,model and color too!

[tilt]

Originally Posted by GoBlue

Sharing observations based on a Polo GT TSI driven for 48k+ kilometers.



If the brake is applied 100%, the car does not roll back after releasing the brake (whilst the accelerator pedal is not applied).

However, in my observation if the brake pressure is not applied 100%, the car does roll back slightly after releasing the brake pedal.

GoBlue, thank you for testing. Yes, brakes are applied 100%, that car actually comes to a complete stop.

Originally Posted by audioholic

As far as I am aware, the two technologies are slightly different in how they are implemented. In case of Hill Hold, you are required to press the brake pedal hard and that pressure is held by the ABS/ESP module for a while before it is released. Hence, you should ideally be pushing the brake pedal hard for the car to hold it after you release the pedal. Do check if the car rolls back even after you press the brake pedal hard. If thats the case, then check if the roll back is intense or gradual. Intense rollback will mean the pressure was never held, while a gradual rollback will mean the ABS/ESP module will have a leaky/malfunctioning solenoid valve. If its the latter, then it isnt a good thing. But if its the former, then it would be an external factor and the troubleshooting process will be valid.

Typically it should work for a slight press of the brake pedal also but that press must be hard enough for the vehicle to come to a standstill manually too. If it works fine with a hard push of the pedal, the issue can be something as simple as improper bleeding of brakes. Please get it done if that hasnt been done yet. Air in the brake lines will make the brake response spongy. Especially if the air is downstream of the module, even though the module can hold the pressure, air which is compressible will play havoc and wont engage the brakes properly. Like the name goes, its a hill hold mechanism and cannot build its own pressure to keep the car standstill. Whereas, AFAIK the auto hold uses the electronic park brakes which can be engaged and disengaged automatically. But the usual hill hold is a mostly mechanical tech with very little electronics or software playing around.

Brake pressure is hard enough to bring the car to a complete stop, in case that's what you mean. I never tested by pressing very hard on the brakes because that brings the car to a sudden and jerky stop - I usually try to brake smoothly enough that the passengers to do not feel any sudden change in motion. However, to reiterate, the braking is hard enough to bring the car to a complete stop.

And, if it were indeed a leaky/malfunctioning solenoid valve, I would expect that it would throw a fault code maybe? Would it be possible for this to happen with no fault codes?

And I forgot to add, the brakes themselves are working absolutely fine and crisply while driving. So, my doubt here is - if the issue were improper bleeding, ,would it or would it not show up in normal brake-operation?

If I am not catching your drift, please continue snowing

Thank you, both of you, and cheers

[audioholic]

Originally Posted by tilt

Brake pressure is hard enough to bring the car to a complete stop, in case that's what you mean. I never tested by pressing very hard on the brakes because that brings the car to a sudden and jerky stop - I usually try to brake smoothly enough that the passengers to do not feel any sudden change in motion. However, to reiterate, the braking is hard enough to bring the car to a complete stop.

And, if it were indeed a leaky/malfunctioning solenoid valve, I would expect that it would throw a fault code maybe? Would it be possible for this to happen with no fault codes?

Well, you could press the brake gradually by all means to keep things comfortable with the passengers. But once the car comes to a stop, a little bit of extra pressure would not make a difference in comfort or would it be felt. Like I explained earlier, the Hill hold system can only hold the pressure you applied to the brakes. Compared to this, the auto hold system can add pressure if it detects that the car is moving. Hence, its pretty straight forward to understand why the HH system is not working or if its working in the intended manner. For all the sake of simpler discussions I would refer to the ESP module for the ABS/ESP/HH unit since its all in one box.

Lets say you apply the brakes normally on an incline. The ESP module must detect the incline and hold the applied pressure on all wheels. If it hasnt detected the incline, then probably the IMU in the ESP unit is faulty or not calibrated correctly in this scenario, the vehicle will roll back as if the brakes were released naturally and there is no HH system. If it detects the incline and holds pressure, then the car must not roll back - working correctly. If the car rolls back in this case, then the reason is that the pressure isnt sufficient, or there is loss of pressure somewhere in the system. Then the roll back will be gradual or slow. This loss of pressure could be at the valves which are controlled by solenoids, or could be because air in the system is acting cranky.

Now coming to the diagnostics part, these systems can detect a faulty solenoid based on the electronic characteristics only. For example, if the solenoid is short circuited, or open circuited, there will be an error showing up. But the valve is a mechanical part, and it isnt possible for the system to detect that there is a minor leakage of sorts, but this is quite rare to occur.

If you can do a step by step analysis on this behavior then probably some clarity will be achieved as to what the issue could be, or if its normal behavior. I am not sure if I can explain beyond this, but perhaps someone else could.

[tilt]

Originally Posted by audioholic

Well, you could press the brake gradually by all means to keep things comfortable with the passengers. But once the car comes to a stop, a little bit of extra pressure would not make a difference in comfort or would it be felt. Like I explained earlier, the Hill hold system can only hold the pressure you applied to the brakes. Compared to this, the auto hold system can add pressure if it detects that the car is moving. Hence, its pretty straight forward to understand why the HH system is not working or if its working in the intended manner. For all the sake of simpler discussions I would refer to the ESP module for the ABS/ESP/HH unit since its all in one box.

Lets say you apply the brakes normally on an incline. The ESP module must detect the incline and hold the applied pressure on all wheels. If it hasnt detected the incline, then probably the IMU in the ESP unit is faulty or not calibrated correctly in this scenario, the vehicle will roll back as if the brakes were released naturally and there is no HH system. If it detects the incline and holds pressure, then the car must not roll back - working correctly. If the car rolls back in this case, then the reason is that the pressure isnt sufficient, or there is loss of pressure somewhere in the system. Then the roll back will be gradual or slow. This loss of pressure could be at the valves which are controlled by solenoids, or could be because air in the system is acting cranky.

Now coming to the diagnostics part, these systems can detect a faulty solenoid based on the electronic characteristics only. For example, if the solenoid is short circuited, or open circuited, there will be an error showing up. But the valve is a mechanical part, and it isnt possible for the system to detect that there is a minor leakage of sorts, but this is quite rare to occur.

If you can do a step by step analysis on this behavior then probably some clarity will be achieved as to what the issue could be, or if its normal behavior. I am not sure if I can explain beyond this, but perhaps someone else could.

The bolded part - yes, thank you, now I get your drift

To answer your question., yes, once stopped, I do use more pressure on the pedal and hold the car on the incline in Neutral. Sometimes, if it is a traffic light, then I pull the handbrake and take my foot off the brake pedal.

So, in the traffic light scenario, I would get my foot back on the brake, with some significant pressure, shift into Drive, give a little acceleration while simultaneously releasing the handbrake, exactly like in a manual car on a slope. I have got into this habit because otherwise, the car rolls back most of the time.

In other scenarios where I may not be stopped for any significant amount of time, I either hold the car with just the brake pedal (with significant pressure), and gear either in Neutral or Drive depending on how long I expect the stop to be - say in slow moving traffic or in a traffic jam.

All that said, I shall still take your suggestion and test specifically the way you ask me to and I shall post my results here.

I appreciate your patiently explaining this to me, thank you.

Cheers