T6 TPI - Start-stop System Fails Intermittently, Engine Does Not Switch Off Or On -

[Dellmassive]

Being a T6 geek and spending my Sunday afternoon trawling through T6 TPI`s and Service info i thought i would share this with you.

stop/start is a very complex system even though you would assume its simple.

An interesting read IMO and details the stop/start requirements and issues/non-fault scenarios.

T6 TPI - start-stop system fails intermittently, engine does not switch off or on -



11/14/2018 Technical product information 2039908/1




Technical product information:
Service info: start-stop system fails intermittently, engine does not switch off or on Transaction No.: 2039908/1
Release date: 27-Feb-2015

Customer statement / workshop findings:

The start-stop system fails intermittently. The engine is not automatically switched off or on.


Technical background:
This TPI only applies to vehicles with the with start-stop system.
The start-stop system allows automatic engine stops and starts.
Because of different factors the engine may not automatically be switched off although the driver expects it.
It is also possible that the engine starts automatically although the driver does not expect it.
For the start-stop system to work there must be no incorrect function and no event entry in the control unit that could affect its operation.


The engine is automatically switched off if the following conditions apply:

• The minimum engine temperature has been reached. Unless this is the case, the system does not switch off
the engine to avoid interrupting the warm-up and to ensure that the heating is available as quickly as
possible.
• The vehicle has exceeded 3 km/h and driven a few metres before coming to a complete standstill.
• On automatic vehicles more than 10 km/h must be reached.
• The charge level of the battery must be sufficient so that the engine can be restarted. To ensure this the
battery manager constantly monitors the charge level of the battery.
• The defrost function of the windscreen is deactivated and the outside temperature is over 3ºC.
• The driver must wear a seat belt.
• A gear must not be selected.
• The clutch must not be pressed.
• The driver door and the bonnet must be closed.
• The engine speed must be below 1,200 rpm.
• The diesel particulate filter (DPF) of the engine must not be in the regeneration process.
• The difference between target and actual interior temperature must not be more than 12ºC.
• The road incline must be under 10º.
• The steering wheel must not be more than 270º (3/4) turned, as the vehicle comes to a standstill.
• On automatic vehicles the brake pedal must be pressed and held as long as the start-stop function is to be
active.
• -
• -
In the following situations the engine is not automatically switched off:
• The vehicle is electrically connected with a trailer.
• The system was manually deactivated with the button on the centre console.
• The clutch is being pressed.
• A gear is selected.
• The brake pedal is not pressed sufficient hard and held.
• The parking aid is switched on.
• The interior temperature selected on the air conditioning system has not yet been reached.
• The charge level of the battery is too low.
• The windscreen is being defrosted.
• The steering wheel is turned more than 270°.
• The vehicle is inclined too much.
• The system remains switched off, if after a replacement the battery has not been adapted with the Guided
Functions or if after such an adaptation the system is in the process of calculating the charging curve. This
process takes about 10 start cycles and varies depending on vehicle and equipment.








In the following situations the engine starts automatically without driver involvement (without pressing the clutch pedal):

• The vehicle moves with switched-off engine and reaches a speed of more than 3 km/h, for example because
of a slope.
• On an automatic vehicle the selector lever position "R" is inserted.
• The coolant temperature drops or rises too much.
• The vacuum in the brake servo has dropped leading to reduced braking assistance.
• The interior temperature differs from value selected in the air conditioning system.
• The outside temperature is below 3ºC.
• The charge level of the battery is below a certain level.
• Many electric electrical consumers are switched on.
• The windscreen is being defrosted.



Requirements for the engine to be started deliberately after being turned off by the start-stop system:

• The clutch pedal must be pressed.
• On automatic vehicles the brake pedal must be released.
• The bonnet must not be open.
• When pressing the clutch pedal the driver door must be closed.
• The seat belt of the driver must be in the belt buckle and must not be released.


Further information about the start-stop system is included in the owner's manual.
Production change


This TPI applies to vehicles equipped with the-start stop system.

Measure

If a customer complaint is confirmed, proceed as follows:
For checking and effectively diagnosing the start-stop system use the Guided Fault Finding.
The start-stop system is complex and the number of the conditions affecting it is high.
Our analysis of the replaced components shows that a high percentage of damaged parts submitted under
warranty are correct and were replaced unnecessarily.
For the technical support and to avoid unnecessary repairs and repeat repairs we recommend to make a
technical repair enquiry if the check of the system with the Guided Fault Finding and this TPI finds no cause.
Always attach the historic and current event entries to the technical enquiries.
Please do not replace parts based on assumptions following the diagnosis. Please inform the customers about
the background and possibilities of the start-stop system.


Warranty accounting instructions
---
Customer information
The start-stop system is complex and the number of the conditions affecting it is high.
Please explain the factors outlined under Technical background. The customer required needs to understand
that the start-stop system may not necessarily malfunction (depending on the result of the Guided Fault Finding).



**************************************************************

why cant you disable perm? . . . . . now you know!

Customer statement:
The customer wishes a permanent deactivation of the start-stop system.


Workshop findings:
A permanent deactivation of the start-stop system is not possible.

Technical background
The start-stop system is an integral part of the registration and must not be permanently deactivated, as it is used for the consumption figures and especially the CO2 emissions for the registration. A permanent deactivation of the system would invalidate the operating permit of the vehicle.



Measure
- Customer information
Explain the background to the customer. It is only possible to deactivate the start-stop system with its button till the next terminal 15 change

 

[mmi]

Having read the above the way I understand is that one definite "rule" is that Start-Stop shouldn't shut down the engine below +3C. But, definitely shuts down well below and they are not going to fix it
----------
VAG Self-study Programme "Start/Stop System 2009" also sheds some light generally on VW Start-Stop system.
Available here --> Start/Stop System 2009 | SSP 426 Online | Free Download

 

[Cherokee]

150 dsg. 2018. My stop-start cut in this week, and upon release of foot brake it would not start. MFD came up with 'vehicle must be started manually' (or similar). I felt a right nob-end at green traffic light as I shifted into P & re started the engine whilst holding up the queue behind me. IMO it's a right pain in the arse.

 

[Sabre]

Damn! That's a complex list of if's and but's to make it work. No wonder it's not consistent. Mine happens sometimes but it's rare at the moment and now I know why. It's more frequent through the summer, which makes sense with the temperature requirements. I've had the manual start thing happen twice but was so hacked off I didn't work out what I'd done.
But I have to ask, how the hell did they come up with that list? Its the camel of the automotive world....
Gotta admit though, some of it makes sense.

 

[mmi]

 

[Dellmassive]

-10.5 AND START/STOP RUNNING.


kinda contradicts: • The defrost function of the windscreen is deactivated and the outside temperature is over 3ºC.

 

[mmi]

-10.5 AND START/STOP RUNNING.

kinda contradicts: • The defrost function of the windscreen is deactivated and the outside temperature is over 3ºC.

I agree. To complement the list of conditions - another a kind of frustrating one:

Captured from thread ---> I tell you what drives me mad about my T6

Just to recap that unfortunately there are some hidden inconsistencies or even failures. Like the "unstart" @Cherokee described a couple of posts ago above.

 

[Pete C]

It’s not just VW that get grief over Stop/Start and whether it works properly or not.

I had an Alfa Romeo Guilietta for a few years, and the complaints on the forum about Stop/Start not working were numerous. People assumed it would just work all the time, but as we know, it has loads of dependencies.

Having said that, Alfa Romeo definitely configured it to be over cautious, and everything had to align for it to kick in when you came to a halt.

Pete

 

[Dieseldonkey]

Since I posted that sometime ago @mmi, for some reason there has since been occasion where I did indeed put the transmission into park and the engine didn't restart when I released the foot brake. Its not on every occasion however. Only when the ground is flat or uphill and there is no rock forward onto the transmission lock and the foot brake is released and released slowly. Its very inconsistent. And as listed above, alot of parameters have to be met. Its a dark art this stop/ start function.

 

[toonaroon]

Wow, talk about food for thought!! Just tested my battery and it's reading 12.1 v and from what I remember being in the trade (a long time ago) that could mean it's been running at that since new, unless alternators are different now???

 

[Dellmassive]

12.1v is basically classed as flat (below 50% state of charge)

Best take your van for a long drive or Plug in the charger before the real cold weather sets in.

Note. some MOL battery's are known to have an issue, check yours and search T6F just in case.

Also smart alternators now are controlled very differently from old school ones. The van ECU controls the output from 0-100% depending on demand and to help fuel economy and emissions.

 

[toonaroon]

Yes I was quite shocked when I put the tester on it, the battery I have is a Varta so not to worried, will be charging and keeping an eye on the levels from now on..
Regards the smart alternators, thanks for that I never new, will have to start brushing up on my mechanical Knowledge...

 

[Dellmassive]

Have a rummage through these...

Stop/start...regen...smart Alternator... Dc-dc Charger For Leisure Battery Or Not?

.
Dellmassive`s -- "how I Done It" -- Thread

.

 

[sam wildcat]

hi what a read that was mines say ERROR stop start when i first start up and has never stop / started Do i have a fault or is it one of the reasons above on ist comment thanks

 

[Robuk]

Quote Wow, talk about food for thought!! Just tested my battery and it's reading 12.1 v and from what I remember being in the trade (a long time ago) that could mean it's been running at that since new, unless alternators are different now??? Quote

You have a smart charging system, here is how to fix your charging problem hopefully with your present battery unless the system has not already trashed it.
Disconnect the small sensor attached to the clamp on the negative rail of the starter battery, this will force the EMU to charge the battery continuously as was the case prior the stop/start. Firstly you will need to fully charge the battery with CTech charger or similar to see whether the battery is still good, allow battery to rest for a few hours then check voltage, should read 12.6 if fully charged, if it`s around the 12.1 it`s probably had it. If good, disconnect sensor then drive van for a few days.
To now test battery voltage release bonnet catch, lock van then wait say 1/2 hour to let vans sensors go to sleep, lift bonnet put multimeter across battery terminals and read voltage, should be about 12.6 fully charged for good battery. hope this is helpful. I run two Merc`s with the sensor disconnected, did it to get rid of stop/start as EMU is locked on Merc`s.

Here is how this system works on Hyundai,

Attached is A PDF from Hyundai UK explaining about the AMS system. The text from this pasted below.
This model has an engine ECU controlled alternator and this is designed only to operate in a way that reduces fuel consumption and emissions. So effectively it will actually do very little unless it really needs to, which means that until it detects an electrical load from things such as headlamps, HRW etc it will do the bare minimum to charge the battery up. If the customer is only doing those sorts of short journeys and not using any electrical items then the starting of the engine has taken charge out of the battery, but without any electrical items being used it won’t put that much back into the battery again. The Alternator Management System (smart charge) works in a very different way to a conventional alternator. The conventional alternator is charging at all times whenever the engine is running, and will increase its output back to the battery depending upon electrical load and the speed it is being rotated at. In the AMS system the charging function of the alternator is controlled electronically by the engine control ECU based upon various sensor inputs and how the vehicle is being driven, so it can be that the alternator will not be charging the battery at all dependent upon the circumstances at that time. Effectively as the alternator is controlled via the ECU it will only charge the battery when necessary, this is to reduce emissions and improve fuel economy. In certain conditions the system will only charge the battery in small amounts.
So if the vehicle is only used for short journeys, and as the system often does not charge at all after a cold start, if you are only doing low mileage the starting of the engine can take more charge out of the battery than the system will put back in again.

Start stop (ISG) and AGM brattery

 

[Deaky]

Quote Wow, talk about food for thought!! Just tested my battery and it's reading 12.1 v and from what I remember being in the trade (a long time ago) that could mean it's been running at that since new, unless alternators are different now??? Quote

You have a smart charging system, here is how to fix your charging problem hopefully with your present battery unless the system has not already trashed it.
Disconnect the small sensor attached to the clamp on the negative rail of the starter battery, this will force the EMU to charge the battery continuously as was the case prior the stop/start. Firstly you will need to fully charge the battery with CTech charger or similar to see whether the battery is still good, allow battery to rest for a few hours then check voltage, should read 12.6 if fully charged, if it`s around the 12.1 it`s probably had it. If good, disconnect sensor then drive van for a few days.
To now test battery voltage release bonnet catch, lock van then wait say 1/2 hour to let vans sensors go to sleep, lift bonnet put multimeter across battery terminals and read voltage, should be about 12.6 fully charged for good battery. hope this is helpful. I run two Merc`s with the sensor disconnected, did it to get rid of stop/start as EMU is locked on Merc`s.

Here is how this system works on Hyundai,

Attached is A PDF from Hyundai UK explaining about the AMS system. The text from this pasted below.
This model has an engine ECU controlled alternator and this is designed only to operate in a way that reduces fuel consumption and emissions. So effectively it will actually do very little unless it really needs to, which means that until it detects an electrical load from things such as headlamps, HRW etc it will do the bare minimum to charge the battery up. If the customer is only doing those sorts of short journeys and not using any electrical items then the starting of the engine has taken charge out of the battery, but without any electrical items being used it won’t put that much back into the battery again. The Alternator Management System (smart charge) works in a very different way to a conventional alternator. The conventional alternator is charging at all times whenever the engine is running, and will increase its output back to the battery depending upon electrical load and the speed it is being rotated at. In the AMS system the charging function of the alternator is controlled electronically by the engine control ECU based upon various sensor inputs and how the vehicle is being driven, so it can be that the alternator will not be charging the battery at all dependent upon the circumstances at that time. Effectively as the alternator is controlled via the ECU it will only charge the battery when necessary, this is to reduce emissions and improve fuel economy. In certain conditions the system will only charge the battery in small amounts.
So if the vehicle is only used for short journeys, and as the system often does not charge at all after a cold start, if you are only doing low mileage the starting of the engine can take more charge out of the battery than the system will put back in again.

Start stop (ISG) and AGM brattery

Not sure this is correct. I have a permanent battery monitor on my electrical system and I’ve never seen my alternator not charge the starter battery after starting, irrespective of whether I’m using a heavy load. The alternator will also dump charge back into the battery on braking, that’s one of the reasons why it’s not kept at full charge.

 

[Robuk]

Not sure this is correct. I have a permanent battery monitor on my electrical system and I’ve never seen my alternator not charge the starter battery after starting, irrespective of whether I’m using a heavy load. The alternator will also dump charge back into the battery on braking, that’s one of the reasons why it’s not kept at full charge.

This is the Hyundai system, My 2 Merc`s charge at 14.2 after starting car then drop back to 13.8 float, so appears different, this is with sensor disconnected The charge voltage with sensor disconnected NEVER goes below 13.8 volts therefor I always have a near fully charged battery. With smart charging/regeneration you have no control over when the battery will be fully charged if ever, it appears that if you mainly do short journeys with little regeneration you are likely to end up with a near to flat battery most of the time. I expect my battery to be as close to fully charged all the time, it appears with smart charging you don`t get that. The simple test is if you are having to charge battery overnight with CTech or similar, fully charge battery, disconnect sensor and drive vehicle, if the battery remains near to full that should show that the battery problems are down to this smart charging system.

Dealers are testing batteries as OK then advising customers to charge battery with a charger, that surely indicates something is wrong with the charging system.

 

[Deaky]

I really don’t see what the problem is. The only people who have reported battery issues are those with the faulty batch of MOLL EFB batteries.

 

[Pauly]

We get it you don’t like this system

Agreed there’s no reason to disconnect anything, flat battery = faulty battery (or faulty something else)

If you understand the pros and cons of this action fair enough but unplugging it has onward consequences

 

[Robuk]

I really don’t see what the problem is. The only people who have reported battery issues are those with the faulty batch of MOLL EFB batteries.

Have these replacement batteries been in the vehicles long enough to test the charging system, flat battery complaints are not just in this forum, anyway you also get rid of stop start, that 2 birds with one stone, NO stop/start and always have a fully charged battery.