Well a brake light switch is about £8 and takes 5 minutes so would be worth eliminating? Have you read for fault codes ?

 

Plan in place to do both, just need to find someone with a good code reader.

 

Definitely start with a diagnostic scan as if it's managed to light up a warning light it should be logged.
It could be anything from an exhaust gas temperature sensor malfunctioning (I had similar on my van - no loss of power but intermittent glow plug light flashing) or it could be faulty EGR etc. getting clogged up etc. Either way a scan should point you in the right direction and save you spending out on something that might actually be at fault.

 

Hi @64 SPLIT and @stuartt5t30 So I've not read the codes yet, but I did go to replace the brake light switch. However, I don't have one fitted. There is not one present on the clutch pedal either. The holes for them are there. There is also no cabling so no point in fitting the new one. How can that be explained? Mine is 2012 T5.1 so was it removed as part of the facelift do you think?

 

Also, no codes at all.

 

What are you scanning for codes with, and did you do a full vehicle scan of ALL control modules? Some generic code readers can't extract some or all VW codes.
VCDS will definitely find any stored codes.

 

What are you scanning for codes with, and did you do a full vehicle scan of ALL control modules? Some generic code readers can't extract some or all VW codes.
VCDS will definitely find any stored codes.

Yes, I think I'll have to try a better one. I'm going to get a TopDon for Christmas (well I'm going to buy it for present for my son) then borrow it!!

 

I'm confused as to how you don't have either clutch or brake pedal switches. Either way a full diagnostic scan should throw something up (VCDS will show pending faults too - issues that haven't presented themselves enough times or beyond set parameters to be logged as permanent faults). You'd also be able to run live data too whilst driving it and recreate the situation in which you say the light flashes and see if you're getting unexpected spikes in data (ie from an EGT sensor)

 

@64 SPLIT Reading another post the problematic switches were removed from the pedals in the T5 facelift so that would explain that. It is now a magnetic switch on the master servo, something to do with hill start assist and auto braking. So I'll have to log it as I drive with VCDS, do you have link to where I could buy one from. Presumably I just need a cable then I can download the free software?

 

I have read somewhere that flashing indicates the Glowplugs are not working optimally

 

I'm surprised to hear about the lack of the pedal switches too. They are still listed by VW. This is for a 2014.

 

If there are no swiches how do the brake lights work? I can understand the clutch perhaps if there is no Cruise but not the brakes
not sure if this is the same?

 

No, it's different to that. No Engine Management Light and only intermittent flashing when up to temp, nearly always in 5th gear between 1700 and 2000 rpm when I accelerate relatively hard. If I back off (a bit) then the flashing stops I've not checked but there is apparently a magnetic switch on the master servo (see link above) I have hill start assist and cruise control so maybe that's why? If I come to a stop on a hill, the van holds itself on the brake for about 2 seconds so I can pull away without using the handbrake.

 

Well they are definitely not there on mine (see link) No loose cabling to speak of either to even connect to. I've had no problems (with brake lights) since I've owned the van. But now the weather is colder it's very lumpy when cold. Drives fine and idles fine after warmed up a bit. Maybe fuel pressure regulator. It feels like fuel starvation so could that be the cause. Yet to get diagnostics on during a run. T5.1 2011 brake lights on

 

I'd forgotten that thread from 2016 even though I was part of it! I agree with triffic's comment in it about needing something more accurate
than a plastic mechanical switch for some of the more modern driver assist functions. I see l suggested it might be part of the brake servo. It's worth having a look at that to see if that is correct. Post some pics if you can.

I can only speak for genuine VCDS but you are right in that once you buy their cable, the software and updates are free for life. (Mine has been updated free since 2001!) You can cut the cost slightly by limiting your cable to either 3 or 10 VIN numbers which you choose in advance and simple fault code reading doesn't count so you can code read for as many mates as you like.

 

If it has that you may find it also has brake hold when stationary in gear, to test it just give the pedal an extra push down briefly and the handbrake light should come on, most VWs with that system also have the hold function and the traction etc it all works on the same system have had it on a Passat and 2 Skoda supurbs, my E class has the same system fitted sure helps the leg in traffic jambs! when you set off it automatically senses the clutch coming up or the accelerator going down and releases, good luck with the fault

 

Can you give more details of your van please, auto or manual, year and engine power. Do any of the related functions like hill start assist or cruise control work?

 

TRANSPORTER T30 BMT TDI SWB, 2012, Manual. I think is 104 BHP, pulls quite nicely. Hill start assist and cruise control all work nominally. No other issues with anything, just a bit stuttery when weather is cold right now. Above 12 or 13 degrees all good, other than the coil light flashing (which I can reproduce reliably)

 

Cruise control gets switched off immediately if any input to it is not working correctly and it must be the same for other safety related functions. I'd be surprised if there can be much wrong with the brake light switch (wherever it lives) if the CC and the hill start both work. The only exception to that is the fault is temporary. I have an 'implausible signal' for the CC switch on my van so it will suddenly stop working but if the fault stays away for a while it will allow CC to be set again. But a code is always left for each event of course.

Address 09: Cent. Elect. Labels:. 7H0-937-049.lbl
Part No: 7H0 937 049 K
Component: BORDNETZ SGVER 1.0 1901
Coding: 0000551
Shop #: WSC 02756 785 00200
VCID: 3A7FC64E7610145FC1-513C

1 Fault Found:
00895 - Cruise Control Switch (E45)
008 - Implausible Signal - Intermittent

Your bad running could be something as simple as a fuel temperature sensor or fuel pressure sensor or it could be a turbo fault but it needs a full scan on diagnostic as a basic start point because you could be guessing expensively for a long time! .

Your van should be running perfectly however cold it gets.

 

Glow plugs aren't used once the engine is started - and even then they only come on when it's particularly cold. I'd suspect injectors or fuel sensors as T5 TDI mentioned above.
VCDS is expensive to buy so unless you have a friendly mechanic friend or want to pay someone to do the data reads for you, you may be better off looking at some of the other 'subscription' service OBD scanners like OBD11 or Carista so you can cancel the payment once you've got the information you need from it.
These should allow you to scan and read live data too but don't hold me to that as I haven't used either (always stuck with VCDS).

 

Glow plugs aren't used once the engine is started

That's true of the pre-facelift engines, but it got more complicated with the 2 litre engine:

"Post-heating is performed up to a coolant temperature of 64°F (18°C) after the engine start for a maximum of five minutes. Post-heating helps reduce hydrocarbon emissions and combustion noise during the engine warm-up phase."

So I ~think~ on the later engines you might still get a warning light for a glow plug fault even after engine start. But without doubt you would also get a fault code logged in that case.

 

Yeah that's what I was thinking as the OP stated the issue only occurs when the engine is up to temp - so wouldn't be the glow plugs.

 

One other possibility is the EGR valve. On the 2.0 engines the failure rate is fairly high. They can cause poor cold running if they are failing. You can't really do much more until you get diagnostic kit which will almost certainly have some codes. Post anything you get here and if we can help we will. If you don't mind saying roughly where you are located there might be someone not too far away with VCDS.

 

I'm in Gloucestershire. My TOPDON has arrived today so will check with that.

 

OK so no fault codes. But using my new TOPDON diagnostics was able to determine that fuel pressure was fluctuating heavily. Since the weather has got cold and damp I have a very rough idle. Researching posts on this site I have determined that I have a faulty fuel pressure regulator or IMV. So can anyone tell me the part number for a new fuel pressure regulator? I think it 057130764H and I can get them on fleabay. Are these OK? I also have a sensor and new fuel filter ready to be fitted. This may or may not also fix the coil light flashing in my OP. Van drives OK but just very rough idle, but not as rough when warm. Rough idle has only started since the weather got cold pas week.

 

Update - Replaced Fuel Pressure Regulator, Fuel Pressure Sensor and Fuel Filter. Rough idling has gone away now and engine sounds much better, no matter the temperature. Was fine for a the first run but now I get code P0191 Fuel Rail Pressure Sensor A Circuit Range / Performance. I can clear the code and it runs fine, then after a while at next start the code will return. Engine starts and runs fine even with the code, I clear the code and it comes back though. Is it possible I have a pressure leak, or do I need to 'run an adaption on the fuel pressure regulator' to reset it to what it thinks it should be now I've replaced FPR, and Fuel Filter and Sensor with new. BTW the glow plug still flashes briefly, when up to temp, and under acceleration but appears more often now.

 

My first port of call would be changing the glow plugs I think one of them on cylinder 3 has some kind of pressure sensor in it, you can have a bad one going out of spec and it not show on vcds

 

Update - So I spoke with my trusted garage (who did the fuel filter, regulator and sensor work) and he suggested running an injector cleaner through the fuel and driving for a while. So I did that last night (Wynns Extreme Diesel Clean), added to quarter tank of fuel. Drove 65ish in 4th (3250 rpm) for about 15 miles. Engine light was still on, and still get the coil light flashing (at times) so not hopeful the P0191 Code was gone.....BUT this morning the engine light has turned off which I was not expecting, could be the high revs for while but I'd already tried that. Early days so not counting my chickens but the Wynns looked to have helped with P0191 Code. I think the coil light flashing when accelerating maybe a timing issue but I'll monitor. Found the exact same issue on another forum after I trapped the code P0016 when driving. P0016 - crankshaft sensor and camshaft sensor correlation error

 

Update - So after timing belt was replaced today and timing now all as it should be the coil light flashing under acceleration has gone. The fuel pump was 2 teeth out of timing it was discovered.

 

Thanks for getting back. The HP pump on a VW common rail engine doesn't have a mark to line up. It just pumps and the ECU does the timing. It must be the valve timing they were talking about (hence the cam/crank correlation code). Some other engine makes do have a pump mark for balance but not VW.