Hi!

I have had my third OctyII (2.0 TDI PD) for 14 days now. This one is the first to rattle like a snake – periodically – while driving on the highway.

Today I did a little faultfinding session trying to locate the circuit causing the sound. It turns out that the sound is linked to the use of the cruise control.

It is under warranty, so I don’t think it will be a large issue. – However I would like to know if any of you have experienced having a “speed controlling rattlesnake” in the dashboard?

By the way – I can confirm that the VW Ipod unit sucks – the sound quality is extremely poor. My Stream MP3 sound quality is interfered, probably by the CAN bus digital signal? – in AUX and Phone mode. However, I do NOT know if this problem is caused by the VW Ipod unit.

I love the car and consider the mentioned problems minor and I expect (hope) they will be sorted out smoothly..

For general information: My first OctyII – 1.9 TDI PD – suffered from the Fly Wheel problem mentioned in another thread in this forum. I used quite some time and threats to convince Skoda Denmark that it were NOT normal. After a struggle they fixed the problem under warranty.

Great Forum – Briskoda!

Regards AGB

Hi,

have you confirmed that the ground is properly connected on the VW Ipod cable?

About the strange sound...I have noticed a similar sound, it starts every now and then (every few minutes maybe) and lasts for maybe 10 seconds. I think it sounds like some fan starting to spin and then stop, as the sound fades in and out just like a fan would start and stop. At the end there is a clear "click" sound from some relay just before the sound stops.

Does the sound stop if you turn off cruise control when you hear the sound? I haven't tried this, have to try it today.

Does this sound the same as in your case? I'm also under warranty and will contact the retailer at some point.

I can confirm that the VW Ipod unit sucks – the sound quality is extremely poor.

Sorry to hear this, the sound quality from mine is fantastic, with no interfernce at all.

I did have problem due to a change in the loom/headunit wiring - this may help http://www.briskoda.net/forums/ice-security-insurance/skoda-ipod-interface-model-year-2007-cars-important/65921/

Thanks for the IPOD advice! I have tried the IPOD unit connected to an old generation IPOD, as I got the 6th generation, not mentioned on the papers from VW. Anyway, the sound quality is poor either way. The repair shop intends to exchange the IPOD unit to a new one sometime soon - I will give your advice to them!

Regarding the rattlesnake issue - the sound were not present in my two pervious OCTY II cars. And Yes, I can stop the noise by turning OFF the cruise control.

The repair shop has reset the car and re-programmed it, re-enabling the cruise control feature (and the other accessories fitted in the car). I can not make my final conclusion yet, but I haven't heard it since (got it back two days ago).

Did you try to disable the cruise control while the sound was present? Did it have any effect?

Hi,

I had cruise control enabled when I heard the noise - I disabled it, but the sound was still there (stopped after a while, just as it always has). Probably some other issue then...well, it's not a biggie - I'll ask about it the next time I visit the dealer.

Hi!

Well, here is some more information regarding my rattlesnake hunt. The shop tried to reset the cruise control, as I described previously, however, “the snake woke up again”, and I still got the rattling noise.

Today I did some experimenting – again – trying to locate the series of event enabling the rattling noise.

The noise appears only when the front screen wiper is activated – If I activate the wiper function with the timer, then the noise appears after approx. one minute of driving (with or with out the cruise control activated). It rattles for approx. 30 seconds, and appears again one minute later etc.

I can interrupt the noise by disabling the cruise control or by taking my foot of the gas pedal.

I can reproduce the result again and again.

Anyway, I will pass the information to the repair shop and they can have fun with it..

I agree the problem is to be considered minor – yet still annoying.

Would it be some sort of timer relay for the wipers ? I'm not sure but would the wiper setting also be speed dependant, hence why the noise changes when the speed is interrupted when on cruise (as its changing the timer setting).....just a thought.

Well, I had the same thought; however, I do not think that the wiper timer is speed dependent. I tried to change the wiper timer setting and even turn off the wipers while the sound appears – no change…

I wonder if the wiper relay or circuit is missing 0V/ground, and gets it via a not intended track, when I decrease the speed…. Well, I passed the info to the repair shop.

I will let you all, if there is any cure or news.

To let you all know I post an update on the issue. The repair shop exchanged a step motor in the climatronic system. I wondered , however, they are the experts….

I suggested that they checked all 0V connections in the area left to the driver. They did.

I still got the rattlesnake in the car, and now the sound is accompanied by a vibration/humming, probably coming from the engine. The eco meter shows increased diesel usage during the rattling period (approx 1,2L per 100 km). I have discovered that the problem also occurs without the cruise control active, I then have to set the speeder limit (pedal) to a fixed level or accelerating - no de-acceleration during a certain period.

Well, I decided to investigate the problem my self, and I found some information regarding the CAN and LIN busses in OCTY II, giving a good overview of the car electronic system. Volkswagen Technical Site

Facts about the problem:

The rattling sound comes from the area around the fuse box, left to the driver. It sounds like a relay toggling – or similar. The sound occurs only when the wiper is on (no matter if it is on delay or continuous mode). The sequence (sound) can be interrupted/removed by moving the foot from the gas pedal. It only occurs if you either have enabled the cruise control or you keep a fixed gas pedal limit (or accelerates) for a certain time (around 2 km at 80 km/h.). The fault has influence on the engine and gives vibrations / humming sound in the car. The sound level increases during the rattling sound period.

After reading the information (se link above), I am pointing at the “Onboard Supply Control Unit J519” as troublemaker.

The box is installed at the location where the rattling sound comes from. Its main function, among others, is: “Windscreen wiper and washer system” and ”Fuel Pump feed (pressure build-up)”. One of the relays mounted on the unit is switching the Fuel Pump feed on and off. If that relay toggles, then the available fuel pressure at the engine varies, possibly affecting the engine, causing the vibrations / humming.

The signal from the right arm near the steering wheel (enabling the wiper function), is sent via a “steering column electronics control unit” – and then via the CAN databus “convenience” to the “onboard supply control unit J519”. Right now I don’t believe that the “steering column electronics control unit” causes the problem; however, it might - in theory - be a possible cause.

The ”Onboard supply Control unit J519” sends the information from the wiper control (arm) to the wiper motor (containing contol unit) via ”LIN databus”. The “LIN databus” is distributed in three subsystems – Onboard supply control unit – convenience system central control unit – steering column electronics control unit. I do not have information about the dataflow and validation on the LIN-bus, so I can not determine if the wiper control unit / motor can affect the function of the “Onboard supply Control unit J519” – maybe it is a possible cause to the problem…

Both “J400 Wiper motor control unit” and ”J519 onboard supply control unit” are connected to the LIN Bus.

Well, a lot of information and thoughts…. I have passed my theory to the repair shop, and they have contacted a specialist to evaluate if the above written is the possible cause to the problem. I will let you all know sometime later.

For general information: My first OctyII – 1.9 TDI PD – suffered from the Fly Wheel problem mentioned in another thread in this forum. I used quite some time and threats to convince Skoda Denmark that it were NOT normal. After a struggle they fixed the problem under warranty.

Was it a manual one????????????

Facts about the problem:

The rattling sound comes from the area around the fuse box, left to the driver. It sounds like a relay toggling – or similar. The sound occurs only when the wiper is on (no matter if it is on delay or continuous mode). The sequence (sound) can be interrupted/removed by moving the foot from the gas pedal. It only occurs if you either have enabled the cruise control or you keep a fixed gas pedal limit (or accelerates) for a certain time (around 2 km at 80 km/h.). The fault has influence on the engine and gives vibrations / humming sound in the car. The sound level increases during the rattling sound period.

Sounds like it's the automatic brake dry/wipe function in action. This function applies a little bit of brake to dry the discs during heavy rain or otherwise very moist conditions.

It's a feature of the newer ESP system introduced in MY07 cars and onwards.

It only activates when the wipers are on and the speed is over 60km/h.

Yes, it was a manual transmission model. (My previous 105Hp OCTY II)

Thanks for the info about the automatic brake dry/wipe function; I was not aware of that.

Well, I will get back with more info later, when the repair shop has had another try...