I installed the AVIC X920BT in my 2004 Audi S4. When it's hooked up, it causes this high-pitched whining/whistling noise that goes up and down according to the engine's RPMs. It is very noticeable at idle and at some points it becomes even louder than the music I'm listening to. It sounds like a combination of radio interference and a supercharger.

I've been told a bad ground can cause this. I inspected the headunit's ground today and sanded down the whole area around the bolt to bare metal, but the sound still persists. Someone on another forum recommended that I might need some type of special wiring similar to what a laptop power cord uses. Currently the two power wires for the headunit(red and yellow, I believe it's switched and constant? I can't remember) run to the fuse box where one taps in to the windshield wiper fuse and another taps into the radio fuse. The headunit works fine in every way except for this whine noise.

Does anybody know the cause of this? Is it from tapping into fuses in the fuse box? Is it the ground wire? Something else..?

u runninng an amp?

u runninng an amp?

nope, just the headunit with everything else stock.

I also have the GPS antenna sitting on a metal platform near the fuse box. Don't think that could be the cause of any issue but figured I would mention it.

anyone have any ideas?

anyone have any ideas?

Try floating the ground. Sometimes there is a difference resistance between the car's antenna and the ground wire. some antennas offer enough gound to power a car stereo.

Disconnect the ground wire from the chassis and see if the system still works.

If it does, you don't need to connect the ground wire to the chassis because the antenna is acting as the ground.

with it being a S4 instead of a regular A4, do you know if you have the premium sound system, which means that there is a factory amp somewhere in the car that actually drives the speakers, there could be a difference in resistance in ground between the radio and the factory amp, if this was the case you could try extending the ground wire to the same location as the amp (with German cars, its usually in the trunk)

another easy ban aid sort of fix (if it has the premium sound system) is to use a ground loop isolator (or two for all channels)

Try floating the ground. Sometimes there is a difference resistance between the car's antenna and the ground wire. some antennas offer enough gound to power a car stereo.

 

Disconnect the ground wire from the chassis and see if the system still works.

 

If it does, you don't need to connect the ground wire to the chassis because the antenna is acting as the ground.

It does work without the ground wire well...grounded. I always thought that was odd but didn't know what it means. I did the install a few months ago so I'm having some difficulty remembering exactly how it was all wired. I bought a Metra 40-VW54 Amplied Antenna Adapter and attached that to the headunit as per instructions from an Audi website. I'm not sure if that has any effect on what you're mentioning.

with it being a S4 instead of a regular A4, do you know if you have the premium sound system, which means that there is a factory amp somewhere in the car that actually drives the speakers, there could be a difference in resistance in ground between the radio and the factory amp, if this was the case you could try extending the ground wire to the same location as the amp (with German cars, its usually in the trunk)

 

another easy ban aid sort of fix (if it has the premium sound system) is to use a ground loop isolator (or two for all channels)

I've done some more research and my opinion is somewhat similar to yours. I'm pretty positive I have a premium sound system, I'm fairly sure there is a factory amp, and I'm fairly sure that has something to do with my whining sounds.

I know next to nothing about audio so forgive me if I'm sounding like an idiot. From what I've gathered on google searches, I could have an issue with the RCA plugs that go into the back of the headunit. I think those have something to do with the factory amp. There is some grounding issue with them, or some interference issue where the RCA's are too close to the power plug for the headunit. The recommendations I've seen are either:

(1) solder a ground wire onto each RCA that plugs into the headunit, and ground each RCA individually, or

(2) use a ground loop isolator.

I bought two PAC SNI1 ground loop isolators from Amazon because I've heard that it's pretty likely to fix my whine issue. I'm not entirely sure how they work, where I install them, whether I need 1 or 2, etc. I realize I'm talking in very inexperienced terms as far as audio installs go, and don't even fully understand why I have this whine and why ground loop isolators would fix it. Will these ground loop isolators work? Do they install on the back of the headunit and then plug into the RCA's? Any advice would be appreciated!

well a common cause of "engine whine" is from ground loop, ground loop is caused when the resistance to ground is different, the GLI's will kinda separate the grounds from each other which will clean up the sound a bit, adding grounds to the rca's will only help if the signal grounds are bad in side the unit (this does seem to be becoming more and more common with pioneer's units)

if you used all four RCA connectors behind the radio to integrate the AVIC with the factory amp, then you would need two GLI's (because each GLI will work for two channels)

How did this work out for you? I'm having a similar problem on my '05 Scion xB. I suspected I just needed better grounding and I think I'll be trying that first. I've heard that year and model was given a questionable grounding connection.

How did this work out for you? I'm having a similar problem on my '05 Scion xB. I suspected I just needed better grounding and I think I'll be trying that first. I've heard that year and model was given a questionable grounding connection.

I too had whine (Mazda 3 hatchback) - installed two PAC ground loop boxes ($16 each) and problem was gone - totally silent now. I also had to do this when connecting a simple iPod to the Mazda's Aux input via a Griffin ciggy lighter holder. Bad grounding in the car - not the fault of Pioneer.