Hi. I've got an alternator whine problem in my system that I can not get rid of. I've been posting on some of the BMW specific sites but haven't had any luck and thought I would try over here.
Here's the details on my system: It is a 2003 BMW 530i with navigation and the oem Sirius tuner. I have swapped out all of the speakers for a/d/s components using the stock wiring and replaced the oem amp with a 4 channel Alpine and a mono Sony running an a/d/s sub in a custom enclosure sitting over the battery in the right side rear corner of the trunk. All of the oem electronics - nav computer, Sirius, radio - are in the rear left corner along with the crossovers for the a/d/s components and the Sony amp for the sub. The Sony amp in mounted in the same spot the oem amp used to be located in the this corner. The 4 channel Alpine amp is mounted under the rear deck along with power and ground distribution blocks. There is 4g running to the battery and ground block and then 8g running to each amp. The main ground wire is about 1ft long and is bolted to the metal under the rear deck. BMW has a 12-pin and a 26-pin connector that carries the radio line level output, speaker outs, turn on lead, power, and ground that would connect to the oem amp. I have the corresponding male connectors and have fashioned harnesses to carry the signals where they need to go. I am using the turn on lead but not the power or ground in these connectors. Speaker outs are 18g Belden twisted pair speaker wire and the line level is being carried over cat5 with rca's one end and hard wired into the connector on the other. I also have an ice>link ipod adapter running from the trunk to the glove box with the actual ice>link circuit and the ipod in the glove box.
With everything above the signal is perfectly clean with no problems. Recently I purchased the BMW bluetooth ULF module to integrate the phone into the car. This sits on top of the nav dvd/computer and has a 54-pin plug on one end and an fakra antenna connector on the other which connects to a small bluetooth antenna sitting under the rear deck. With the ulf connected I get alternator whine. The whine is present with the radio (radio/sirius/ipod) off or on, in phone mode, and in voice recognition mode. If I disconnect the ulf module from the 54-pin connector the whine goes away.
Here are some things I've tried that have not worked:
- removing power to the Sony sub amp which is near the ulf - no good
- run a wire from the ground distribution block to the ground on the 12-pin connector - no good.
- run a wire from the ground distribution block to what I believe is the ground on the ulf - no good
- tie the ground wire from the block, the 12-pin, and the ulf together - no good
- wrap the ulf to remove any conductivity between the metal of the ulf and the brackets it is sitting on - no good
- electrical tape around the exposed bits of the 26-pin connector carrying the line level audio to the amp - no good
- plugging the 12 & 26 pin connectors in the original oem amp - this seemed to get rid of the whine but then, well, I've then removed the amps out of the system and it sounds horrible...
- pulling rca jacks from 4 channel Alpine and powering on - this also go rid of the whine. It did appear that the Alpine was still driving the speakers just with silence so I don't think it was muted.
So it seems that it is being picked up through the line level inputs going to the Alpine amp but only caused by the ulf. Dows anyone have any thoughts on what else I should try to do to sort this out. Any help is appreciated. Thanks!
