Cable causing electrical crackling in dash and speakers.

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Placeborick

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Tried to use vcds on my TTs this morning and kept getting electrical crackling coming from dash display and speakers.
Quickly turned ignition off and removed cable. Tried again assuming cable wasnt connected properly. Same issue.
Reluctant to try again to be honest...
What do you reckon is causing this!?
 
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DV52

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^^^ rick:Hi - interesting observation!

I guess that anything is possible - but it's mighty difficult to comprehend how the addition of a VCDS dongle into the OBD port would cause an electrical problem of concern of the ilk in your question. I also guess that there might be a difference in our respective definition of the term "electrical crackling" - to me, it connotes something sinister and foreboding; an electrical fault simmering away in the background waiting for it's time to avalanche into a serious incident. Again, difficult to join the dots by simply plugging-in a VCDS dongle and interrogating CAN modules.

That said, I've found that it's not unusual when powering up a VCDS cable to hear a "sparkle" sound from the car's speakers as the device interrogates the MIB module @ address hex5F. I've never thought to understand why this happens and I've certainly never been concerned at its occurrence - quite the opposite in fact; I would tend to worry if it didn't happen because it would indicate that the normal hex5F challenge/response dynamic has not been successful.

So, is my "sparkle" noise = to your "electrical crackle"?

Don
 
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Placeborick

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Could well be :-D
I've never heard it before so aborting immediately seemed the safest option.
So nothing unusual?
And no chance of smoking any electrical components? Pulling out mid scan seemed to throw a speaker fault in the drivers bass speaker.
Could it be possible the crackling is a result of the software accessing it on scan?
Apologies for my noob fear of breaking something :-D
 
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Bruce

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So nothing unusual?

I agree with Don - I don't think that if it is coming from audio system there is any concern.
And no chance of smoking any electrical components? Pulling out mid scan seemed to throw a speaker fault in the drivers bass speaker.
Could it be possible the crackling is a result of the software accessing it on scan?
Apologies for my noob fear of breaking something :-D

I do not think there is chance of damaging a speaker. Never heard of any user having such a problem.

Every vehicle on which I scanned an audio system made some sounds when VCDS accessed the module. Pulling mid scan may confuse things and it is not recommended. However, I also do not think pulling the VCDS connection will cause harm. Setting a code? maybe..

Don't apologize for learning. That's why we are here to help.
 
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Placeborick

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Thanks for the reassurance.
I'm handy with tools, not at all with electrics :-D
 
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Uwe

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When exactly does this happen?
When you plug it in?
When you start a scan?
When you access a particular module?

More details please!

-Uwe-
 
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Placeborick

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When exactly does this happen?
When you plug it in?
When you start a scan?
When you access a particular module?

More details please!

-Uwe-

During the basic scan.

I was looking to clear an airbag fault i'd picked up when faffing with my front bumper
 
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Uwe

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Tell us about the computer you're using. Is it a laptop? Is it on battery power, or do you have it plugged into the some source of external power?

Can you make a video of this behavior?

-Uwe-
 
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Placeborick

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Old toshiba laptop, not mains connected.
Sure I can try.
 
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DV52

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Every vehicle on which I scanned an audio system made some sounds when VCDS accessed the module. .

Bruce: now that rick has raised this matter and (I assume) piqued our collective interests in the phenomenon - does RT have a theory as to why the "sparkle" sound happens?

What is it about the challenge/response interrogation process from VCDS that causes this effect? Incidentally, the same dynamic occurs with my OBD11 dongle - so it can't be caused by earth loops (unless the earth pin in the OBD connector itself is implicated).

Don
 
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Bruce

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Bruce: now that rick has raised this matter and (I assume) piqued our collective interests in the phenomenon - does RT have a theory as to why the "sparkle" sound happens?

What is it about the challenge/response interrogation process from VCDS that causes this effect? Incidentally, the same dynamic occurs with my OBD11 dongle - so it can't be caused by earth loops (unless the earth pin in the OBD connector itself is implicated).

Don

Don't know what Ross-Tech thinks. Bruce thinks that during the dialog of/with the audio system for faults, perhaps the system actually does a real fast test to see if speakers are shorted. If it did as this old one thinks, the speaker would likely make a sound. Since one of our techies was in the car once when it happened and I asked about it, the response - yeah that's normal- I quickly learned to ignore it and moved on. I am not quite as curious as some on this.

Maybe someone in the real know will reply.
 
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o33err

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My guess is that it gives out a ping that the mic picks up to verify that the speaker is OK. That's probably why there are Test Freq values in the admaps.
 
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just out of curiosity, when is this supposed to happen? I have scanned my car a gazillion of times and never heard any tone/noise from the 5F.

of course if idle it will power up when polled, but it just plays whatever source was selected as last.
 
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Placeborick

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When performing basic scan.

I'd used it a couple weeks and never heard anything before either.

Tried to get a vid but the mic on my phone isn't great and it didn't pick it up.

Its several seconds into the scan, definitely as it accesses that module.

Nothing has blown up anyway 😄
 
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Uwe

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Its several seconds into the scan, definitely as it accesses that module.
If this happens only when accessing the radio, or perhaps the amplifier ("Sound System", if installed) or a similar module, I really wouldn't worry about it much.

-Uwe-
 
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Placeborick

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Here is the error thrown by the phenomena

2 Faults Found:

0517 - Front Right Bass Speaker
B1062 13 [009] - Open Circuit
[Tieftonlautsprecher Kanal 2: Unterbrechung]
Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 6
Fault Frequency: 1
Reset counter: 20
Mileage: 93670 km
Date: 2020.05.25
Time: 11:44:37

Voltage terminal 30: 12.1 V

0518 - Front Right Treble Speaker
B1064 13 [009] - Open Circuit
[Hochtonlautsprecher Kanal 2: Unterbrechung]
Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 6
Fault Frequency: 1
Reset counter: 20
Mileage: 93670 km
Date: 2020.05.25
Time: 11:44:54

Voltage terminal 30: 12.1 V
 
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o33err

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Those two speakers are normally connected in parallel. It would appear that that speaker line has been disconnected from the HU.
 
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Placeborick

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Those two speakers are normally connected in parallel. It would appear that that speaker line has been disconnected from the HU.

Interesting, I've never messed with that.

However I replaced the drivers door a few years ago.... I will whip the doorcard off and see if everything is connected properly.

Thanks for the info
 
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Placeborick

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There was indeed a dodgy speaker connection on the back of the head unit.
Sorted and the crackles have vanished with it.
Mystery solved. :-D
 
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