Need a Bose owner to Check something.

[sierra248]

I been trying to find out where I am getting a hum from my system and I think I just figured it out. Its hard to hear at low volumes but its there at high ones and just quieter at low volumes.

Can someone with a GT go outside and do this:

Go to Aux Input and Turn it up to say 25, I do it at MAX(34) so I can really hear it.

1. There's probably a noticeable Hum if your headlights are off (Maybe, Maybe not)

2. Turn on your headlights, Does the Hum get much more noticeable and louder.

3. Leave Headlights on and Dim the Instrument Panel lights, thats where my Hums the most.

4. If it doesn't seem that bad to you, Keep turning on and off the headlights, and playing with the dimmer. Can you hear any difference on or off at all?

5. Remember this is with nothing plugged into the AUX port or cig lighter just on AUX and at loud 25+ volumes and headlights on and IP lights dimmed . It happens at all volumes but its easiest to hear with windows up, doors closed and volume up.(Bose, No Sirius)

I'm hoping this is just my car and they can fix it, but it may be a bad ground built into all the cars AUX port(Though I did disconnect entire center console and AUX port and it was still there).

Thanks in advance for checking if you would guys.
Tom

 

[sierra248]

Sorry I forgot to mention, do this with nothing playing. Just leave AUX in Center Console empty.

 

[RelliMS3]

I just tried this out on my GT. Turned it up to 25 and heard a slight high pitched sound like when the tv is on but nothing is playing. There is no change when i flipped the headlights on or off.

 

[sierra248]

Thanks RelliMS3, appreciate it, others please check also. Seems I'm gonna have to take my speed into dealer, ugh hate that. So far havent had to go to dealer.
Tom

 

[sierra248]

Tore out center console, and checked all the connections and such, disconnected the whole center console wiring connector and tried it again, same thing, except it is a small amount louder with the console connected. Disconnected TT to see if maybe that was it, nope. Its got to be a grounding problem somewhere. God I hate to take my car to the dealer. Its a pretty significant HUM when u get it cranked up past 30, and at least twice as loud a hum when the headlights come on, I cant imagine I been driving around with it like this so I'm imagineing it is something new so maybe theyll replace the radio and it will be fine. I put in a cd and really cranked it all the way up in between songs and its almost dead quiet, no hum or hiss or anything, so its obviosly something with the AUX Input, but it must be in the wiring before the Center Console..Hmm
Tom

 

[sierra248]

Figured out another thing, the HUM will only stop if you turn the vol up and the headlight switch to OFF, even just turning the light switch to the first notch where it just turns the running lights on makes same HUM, so its not the HID headlights.
Tom

 

[Abaddon]

There is a ground loop in the AUX in.

It is a well known problem on the 3.

 

[sierra248]

Thanks....?

 

[shockdoctor]

It's waiting for you to get the Sirrius installed. No hum or buzz at any output level from mine. But I do have the Sirrius installed though.

 

[Abaddon]

Thanks....?

lol. sorry

I don't have an actual fix for it yet as it's too cold to trace out the wiring.

The main reason is that the AUX line is grounded in a different location then the head unit. The proper solution is to isolate the AUX in line and add a wire and physically ground it at the head unit.

 

[sierra248]

I have a PAC Ground Loop isolator to get rid of what your talking about abaddon. Took it to dealer Friday, they traced it to the dimmer switch which as crazy as it sound, it only makes the noise when you Dim them, when you set switch to brightest setting, no hum. The Service guy seems to think its in the actual Radio and ordered me a new Headunit and they are installing Tuesday, well see?? They were pretty knowledgeable as far as I could tell. I'm not a fan of going to the dealer at all but its wasn't an awful experience. I'll post where and what dealer when they do the work to my satisfaction.

For all of you who would like to see if you are getting this the instructions are aw little different now, I edited it to include the dimmer switch.
Thanks,
Tom