Ground Loop Noise After BT Install?

Wondering if anybody can point me in the right direction... installed a new TCU unit last weekend so the car would have BT; followed this thread:

http://forum.e46fanatics.com/showthr...=installing+bt

Had a little bit of low frequency noise when I tested post-install in my garage but figured it was acceptable. When I finally had a call come through whilst I was driving, interference from what I think is ground loop noise went through the roof.

Any obvious places I should check first, before tearing the install apart? Does it make any difference that the battery wasn't unplugged when I did the install?

FYI, I only get the ground loop noise when using the BT, radio sounds fine and I'll check the aux first thing tomorrow (was fine before though)

Thanks

Maybe its some kind of othr noise. Why do you say it is ground loop related? How does hat noise sound like?

The best way I can describe it is alternator noise, which I've heard before when I installed a USASpec in a previous car

I don't have any experience with the bluetooth tcu, but you might want to check the back of the radio plugs to be sure they are all tight. I believe the tel audio is carried in the same plug as the cd changer on the back of the radio.

given that you also had that with the USA spec, maybe you want to check your ground in the engine bay? you said its alternator noise, do you mean whine , that increases with engine RPM ?

most answers you'd get is that you have a ground loop. But how to find that damn ground loop, no one says !!! make sure your ground is solid, blah blah, but no real answers !

Try this, measure the the DC voltage in your engine bay between two points. the suspension tower bolt and the engine metal piece to lift the engine with. it should be very close to 0V. it may lead you to somewhere, but maybe nowhere !

I am still on the hunt for that ground loop/bad ground in my car.

Cool, thanks guys