Help appreciated re VW Golf Stop/Start and Assisted Cruise Control problem

I purchased a Diesel 1.6 Bluemotion 132 Golf during the summer. Running perfectly, flew through NCT, but the Stop/Start stopped working about 2 months ago.

I checked the media console and all Stop/Start (And ASS) settings as per service book/YouTube videos etc and decided to replace the battery as the most likely culprit. No joy.

I took it to a well known specialist garage in Liffey Valley last week, explained the Stop/Start problem and that the media indicates "ERROR Stop/Start Deactivated" & "ERROR ASS Deactivated".

The dealership charged me €355 and took the entire day to tell me they checked all the wiring and couldn't find a fault. They said the Stop/Start is maybe because of an issue with the ASS. The only way to find out is replace the ASS at a quoted cost of €2488!!! But if they replace the ASS (which I never use) they can't guarantee it'll fix the actual problem with the Stop/Start.

Needless to say a very dissappointing and frustrating outcome all round to be charged €355 and be told what I told them dropping the car off. I took it to this vendor based on the expectation their diagnostics could identify the problem and remedy swiftly. (I found an article on carbuyer regarding an inflated quote for a similar job which on 2nd opinion at a different garage turned out to be a €50 fix caused by loose screws).

I'm hoping someone on the forum has been through this before and has a solution.

Much appreciated.

*I should also mention the car has never had a bang so problem is not based on damage caused that way.

Polo_Cluvie

I had similar issues with a passat. Turned out by changing the battery it was sorted. I did purchase from main dealer and they coded it in. VW have a budget option for some parts. I done a lot of investigation when I was trying to sort it out. If it's a cold day and you have your heater on rear window defrost etc they supersede the s/s function. Same goes for anything drawing on the battery. As a side note when I did eventually get it sorted the s/s done my head in and I was constantly turning it off 😆

Atlantic Dawn

I was going to suggest changing the battery too...when you did change it did that make any difference whatsoever initially?

Thanks both. Yes I got a (stop/start) battery fitted by Halfords about 6 weeks ago. It didn't fix the issue and the garage last week said the battery charge and specification is ok, so not likely the cause of the error.

Atlantic Dawn

Maybe have a look on some VW specific forums, better to exhaust every possible avenue before shelling out the €2488 if that's definetely needed, here's one...

https://www.vwvortex.com/forums/

blackvalley

https://www.boards.ie/discussion/2058220314/help-appreciated-re-vw-golf-stop-start-and-assisted-cruise-control-problem

I have actually deactivated the stop start permanently . I hate the bloody thing.

Toyotafanboi

I's just leave stop/ start not working.

Is it an original Irish or a UK car?

To be fair, generally stop/ start issues and front assist issues are easy to track down, painfully easy so given the fact that they weren't in this case i'd be questioning does the car have some degree of colourful history? I'd be double thinking that if it's boiled down to wiring checks in the workshop.

The reality of it is, it's probably not worth pursuing getting it working on your car from a financial point of view, particularly if you don't know the cars history very well. Really the garage should have put it to you like that too, just called it a wash and not charged you in the interest of no negative PR vs. the current situation.

If they called you and asked for the €355 before doing the work, you are bunched IMO but if they didn't call you and just stuck you for that i'd probably argue it and they might knock it back to the entry diagnostic fee.

Purely wild guess stuff here, but trying to think what ACC and stop start would take joint information from and the only thing I can think of apart from the J519 is probably the clutch position switch as with the clutch dipped it will prompt an engine start in stop/ start and would also cut out the ACC. That being said you also need to dip the clutch to start the engine and that's working, so maybe not, but maybe. Is the gear shift promper working in the centre of the instrument cluster? If not i'd definitely take a punt at clutch position switch, if you want to take a cheap shot in the dark.

If not, honestly, it's probably a hornets nest, best avoided.

Thanks for all the comments.

Car is an Irish reg, not UK import. I checked vehicle history prior to purchase. No red flags. And service history in the logbook didn't indicate any errors like this, all standard service work. And it was running perfectly at purchase and a couple months after. No bangs or damage. Clutch feels completely normal.

Polo_Cluvie

I know how frustrating it is to have a feature not working correctly on your car and not being able to sort it out. However in this instance I wouldn't bother. You've gone as far as is reasonable and I'd advise stopping there. Genuinely the s/s function is really a pain in the proverbial and I'm always turning it off. Take a fools advice and drive on

I think I'll have no other option as I'm not shelling out €2.5k ontop of over €500 already spent. I'm just mindful that I don't want it creating any knock-on problems and also about resale a bit further down the line.

I actually would like to have the Stop/Start function back. But not at all bothered re the ACC.

You paid too much money for DTC readings, it is not the diagnostics. DTC can read even the 5 years old child. Sure it takes time but at least you should have that data what was really done and what was checked. At the moment you have almost zero evidence and paid for nothing. For that money the bare minimum what I expect is to get wiring test result (including pinout, waveforms)

DTC reading (Done) / actuation (bi-directional)

Service manuals / wiring diagrams (hard to find free)

Actual readings / circuit testing (multimeter / oscilloscope / test light / resistor decade box)

Fault finding

Receipt att for work, charge €312 incl VAT total €354.69.

No alternative solution offered. Just a quote for €2488 if I took the route of ACC replacement.

Sorry, we did not had that information before. At least you have a starting point. I do not like they presented the canbus signals as voltages. It requires oscilloscope to see what really going on. Can High and Can Low must cancel each other out and it is visible only as waveform. So they used multimeter , why there other way 1.8V and 3.2V. I will check later they measured the right pins or not.

Sorry, It is too big, about 2000 pages. Wiring diagram is useless if everything is cross integrated.

Ah right. Well thanks for taking the time to have a look. Much appreciated.

It's a bit of a confusing case. Just find it hard to believe that the fix for the Stop/Start is the ACC and that will cose €2.5-3k on a nearly 8 year old car that's otherwise running perfectly.

Do not pay that money. The further diagnostics I suggest to take a waveform from communication and check module plugged/unplugged. Also you can make a virtual network and use only 1 module there. It must try to communicate by the network. Ok, it is may be too advance for them. The next part is more time consuming but need to figure out what cause the problem. Unplug the connected sensors and other modules (pin by pin, cross integrated), except most important (power and communication). No any external cause then you have internal problem. Yes, it is blind trouble shooting because can not see internal connections.

Schorpio

Had a similar issue with my 2013 Golf.

I bought it from a main dealer in 2016 with only 15k km on the clock. ACC worked fine until earlier this year when 'ACC not available' message would appear when starting the car. No other issues, so figured I'd wait a few months until service time to sort - that was until the battery died a few weeks later. Original battery, so not too much of a surprise there.

Changed the battery (correct spec) - ACC error did not disappear on its own. Had to take to my garage, who is an indy specializing in VW group. As I understand it, he tried re-coded the ACC unit. Only cost me about an hour's labour. (I'm based in Cork though).

Thanks for that. They told me at the VW dealership that the new battery spec seemed fine and it had a charge. I assumed they also checked the coding. But that's good to know.

Did your stop/start have any issues stemming from the ACC problem?

zg3409

Make sure after battery change that car was told new battery (that it was coded). If car thinks it has old dodgy battery it will disable stop start. There is typically a connector right next to battery terminals that measures battery voltage. Make sure this is fully plugged in, as people unplug them to disable start stop, and you may have unplugged during battery replace. Otherwise I would say it's not worth the fix. Stop start may have been disabled in software, some dealers flip bits in the coding to disable it. This was done on BMW mini I owned. On some cars it's hard to permanently disable stop start, so some dodgy changes are made to disable it such as forcing car to read very low temperatures, incorrect 12 volt minimum voltage, or some other input that permanently tells stop start to not activate. It may be hard to identify what was changed. Possibly looking at what is normally done to disable it for you car would be a good start. If it was working before then presumably some value is not within the range to allow stop start to activate. Try to get a list of them all.

Schorpio

https://www.boards.ie/discussion/comment/118257803#Comment_118257803

Strangely enough, no - never had any start/stop errors. Well, I say that - there may have briefly been a start/stop error immediately after the battery was changed, but if there was, it cleared itself on the first drive after the battery change (as I understand it's supposed to).

I am guessing that my ACC error was a persistent error, i.e. if the error gets thrown it needs intervention to clear; it won't clear itself. My mechanic told me that an unstable battery voltage (from a battery which is dying) can affect the CANBUS (communication system between modules in the car), which can cause the ACC to lose it's coding. That's just an guesstimate as to what happened though.

Low voltage can corrupt the memory.