Re: Hum/Buzz from Instrument Panel (car_guy)

I know exactly the sound you're hearing as I could hear it at a low , low volume on my CL500. It is just as you described....like a transformer, flourescent bulb kind of sound. Why yours is so loud is the question.

 

Re: Hum/Buzz from Instrument Panel (car_guy)

Not in my car!

 

Re: Hum/Buzz from Instrument Panel (car_guy)

Hi Steven:
My Phaeton doesn't make any noise either, at least, not that I recognize as a noise.
Can you try to narrow down the noise a bit more for us? In other words, is it present when terminal 30 power (battery power only) is present, or when terminal 15 power (ignition power) is present, or only when the engine is running? Does turning the HVAC system off get rid of it? What effect does turning the sound system on and off, or changing the sound system source (AM, FM, CD, OnStar) have on the sound? What about turning the lights on and off? Does the position of the decor panels over the dashboard air vents (open - closed) have any effect?
Perhaps listen carefully to the area in front of the glove compartment door, see if the noise is coming from in there. Be aware that if you open the glove compartment door, you will hear noises, because the system gets ready for you to insert or eject CD's when you open the door. So, first listen with the door closed.
When you say 'instrument panel', are you referring specifically to the instrument cluster under the binnacle that has the tachometer, speedometer, etc. in it? If so, see if changing the brightness level of the instrument panel lighting with the dimmer switch affects things at all, and pay extra attention to whether turning the main lighting switch from OFF to ON and back has any effect. Let us know, if we all put our heads together, we can probably get the problem solved for you. The challenge will be precisely identifying the source of the noise, and what systems have an effect on the noise.
Michael

 

Re: Hum/Buzz from Instrument Panel (car_guy)

Steven,
I do notice a low-level noise (more of a hum than a buzzing noise, I would say) coming from the general area of dashboard, localized in the center section. The only times I notice this is when I turn off the engine after a long trip, and even then it is barely noticeable. I don't know how long it goes on this way, I never stayed in the car long enolugh!
Stefano

 

Re: Hum/Buzz from Instrument Panel (Motorista)

There is an electric afterrun pump which will circulate coolant through the system (depending on a number of conditions being met) to allow even cooling of the engine. If I remember correctly, this is the same pump (V50) which circulates coolant for the "REST" function on the Climatronic.

 

Re: Hum/Buzz from Instrument Panel (PanEuropean)

Michael's questions and my answers:
Q: Can you try to narrow down the noise a bit more for us? In other words, is it present when terminal 30 power (battery power only) is present, or when terminal 15 power (ignition power) is present, or only when the engine is running?
A: It is present during all three states.
Q: Does turning the HVAC system off get rid of it?
A: No.
Q: What effect does turning the sound system on and off, or changing the sound system source (AM, FM, CD, OnStar) have on the sound?
A: No affect. The volume of the noise remains constant.
Q: What about turning the lights on and off?
A: This affects the volume of the noise to quite a degree if the car is not running, i.e., noise is louder with the lights on and ALL the instruments in the binacle lit..
Q: Does the position of the decor panels over the dashboard air vents (open - closed) have any effect?
A: No. The A/C is turned off during this analysis described here and the noise is present.
Q: Perhaps listen carefully to the area in front of the glove compartment door, see if the noise is coming from in there. Be aware that if you open the glove compartment door, you will hear noises, because the system gets ready for you to insert or eject CD's when you open the door. So, first listen with the door closed.
A: The noise in not coming from the glove box.
Q: When you say 'instrument panel', are you referring specifically to the instrument cluster under the binnacle that has the tachometer, speedometer, etc. in it?
A: Yes.
Q: If so, see if changing the brightness level of the instrument panel lighting with the dimmer switch affects things at all...
A: Has a slight effect, brighter = slightly louder
Q: ...and pay extra attention to whether turning the main lighting switch from OFF to ON and back has any effect.
A: Yes. The noise is substantially louder when the instrument panel (tach, speedo, etc.) light up.
Let me run through a scenario that may shed some light (noise?):
Get in car. Headlight switch is in 2nd of 3 positions. No key in ignition. Small screen between speedo and tach is the only instrument lit and I hear the noise distinctively coming from that area. Turn the headlight switch on to the third position, which turns on all the instruments in the cluster, and the noise gets considerably louder. Turn the headlight switch off and all the instruments except the small screen become unlit and the noise lessens. Sit in the car for approx. 15 seconds more and the little screen becomes unlit and simultaneously the noise completely disappears.
It is certainly not the coolant circulation pump because the noise occurs when the car is cold and hasn't been started.
The noise in definitely originating from the binacle and not the center stack.
Not knowing much about the instruments themselves, I would suspect something to do with the power supply or supplies.
My service writer says he clearly hears the noise while sitting in the passenger seat. He says that VW says, "they all do it" and that it's a normal noise. It is an 'electrical' sound rather than a mechanical sound and is very annoying.
Thank you all for your help.


Modified by car_guy at 9:12 PM 3-17-2006

 

Re: Hum/Buzz from Instrument Panel (car_guy)

Quote, originally posted by car_guy »

Q: If so, see if changing the brightness level of the instrument panel lighting with the dimmer switch affects things at all... A: Has a slight effect, brighter = slightly louder Q: ...and pay extra attention to whether turning the main lighting switch from OFF to ON and back has any effect. A: Yes. The noise is substantially louder when the instrument panel (tach, speedo, etc.) light up.

OK, Steven, I think you pinpointed the source of the problem, and by doing this, you have enabled the rest of us to make well-educated guesses about what the cause of the problem is.
My guess is this: I think you are hearing a noise that is being made by the power supply to the instrument panel lighting. I'm not exactly sure how the instrument panel lighting is powered, it is possible that there might be an inverter or a transformer in that instrument cluster that is used to control the power supply to the lighting for the purpose of dimming it.
The fact that the noise becomes substantially louder when you turn the car lights on (with the main lighting switch) is very significant. When you turn the main car lights on, the instrument panel lights also come on. They are off when the exterior lights are off, including when DRLs are on but the rest of the lights are off. The fact that the nature of the noise varies with the dimming level of the instrument lighting also points to the instrument lighting power supply as the probable cause of your problem.
Instrument clusters are quite expensive (over $1,000 each), and that may account for the technician at your dealership being reluctant to replace the cluster without knowing for sure that it is the source/cause of the problem.
I don't hear any such noise from my Phaeton - so, that kind of shoots down the 'they all do it' comment.
My suggestion to your tech is that he first update the software in your instrument cluster to the very latest version (x21). To do this, he needs to call the VW Technician helpline, and the staff at the help desk can perform the software update by telematics. There is more information about this process (the software update via telematics) at these two posts:
TB: Phaeton Technical Bulletin 90-05-05 "Clock Runs Too Slow"
TB: Distortion in the Display Unit in the Instrument Cluster (MFI, or Y24)
If that does not solve the problem, then I don't think there is any alternative but to replace the instrument cluster. I suggest doing the software update first because there is a reasonable chance that the software update might solve the problem, and if it does, then the only money that will have to be spent will be about an hour's labour (or less) for the software flash. I think it's reasonable for VW to first try and fix the problem with an hour of warranty labour, rather than diving right in there and replacing that very expensive part right off the bat.
While your technician has the experts at the VW Technician helpline on the phone, he or she can explain the nature of the problem (the noise) to the experts, and they will be able to authorize replacement of the instrument cluster if the software flash does not do the job. This will remove the 'risk' from the dealership staff, and my guess is that they are a little scared about replacing that part without the prior consent of VW. Heck, it's even possible that the staff at the technician helpline will say 'order a new instrument cluster', and not even try doing the software update - if, for example, they have encountered this kind of problem before.
If you encounter any more difficulty from the service department, perhaps call the team at Phaeton Customer Care - this is exactly the kind of problem that they are very, very good at facilitating solutions for.
Michael
PS: Thanks for doing such a GREAT job of diagnosis - I sure wish everyone documented things as well as you did.

 

Re: Hum/Buzz from Instrument Panel (car_guy)

Steven,
Let me join Michael in complimenting you on an excellent diagnosis! And let me confirm that, in 6 months and over 11kmiles, i have never heard any such noise from my instrument panel (2005 V8). I have, however, heard a similar buzz coming from multifunction displays installed in early stereo equipment (especially european, like early Revox cd players), which I sometimes repair. In these cases, I have sometimes taken care of the problem by re-routing or shielding *other* cables which happen to run by the display unit inside the machine. I have no diea whether something like this could apply to the Phaeton instrument cluster, however.
Good luck with the repair, and keep us posted!
Stefano
P.S.: Chris, thank you for clarifying the source of my hum: it makes perfect sense that the pump would run for a while after a 300+ mile run.

 

Re: Hum/Buzz from Instrument Panel (PanEuropean)

An update on the resolution of this problem:
The bad news. As Michael suggested, an update to the software for the instrument panel cluster was performed, but had no effect on the noise.
The good news. VW Techline has authorized replacement of the instrument cluster. It is on order and is expected within a few days. Hats off to VW for doing the right thing! And kudos to service writer Brendon Siefert and Bernardi Volkswagen in Natick, MA. I will add them to the recommended dealership thread shortly.
Soon I will be cruising in my Phaeton in complete serenity.
As an aside, many years ago someone at Rolls Royce came up with the slogan, “It’s so quiet, you can only hear the clock ticking." Supposedly an engineer heard about it and said (paraphrased), "Well, we should do something about the damn clock!"