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Scotes 04-20-2008 01:13 PM

03 e39 13th gen bt ulf with alternator whine
I have a 12/02 build 2003 e39 in which I recently installed the 13th gen bt module from bimmernav. I have a retrofitted nav system with two amps tied into the 12 & 26 pin connectors in the trunk. Prior to installing the bt ulf I hod no alternator whine / noise in the system. After plugging in the ulf I now have a faint alternator whine and I am trying to figure out how to get rid of it.

As I have the euro armrest I did not install the try and only have a hack momentary button for pairing. With the euro storage tray in the armrest there really isn't room to keep the button plugged in so that connector is open. I thought that this might be an issue but keeping the button assembly plugged in does not solve the problem.

As I noted I have a set of amps powering the stereo. These are pulling power off of a direct connection to the battery with a separate single ground to the chassis. As the ulf ties into the audio system and it is not tied into the same ground used by the amps I think that is causing the open loop. So I think if I tie the two grounds together it should solve the problem.

I would just tap into the ground wire going to the ulf in the 54 pin harness and run a line to the ground used by the amps. Or, would it be easier to run an additional ground wire from the ground block the amps are connected to to ground point in the 12 pin connector?

Any help on this would be greatly appreciated!

Scotes 04-24-2008 12:57 AM

Anybody got any thoughts on this. Am I gong to blow something up if I try this?

Barney Rubble 05-08-2008 06:59 PM

did you do the install of the amps etc?
If you are able, try removing everything and see if the whine is gone, then add in a component at a time.
My guess is that the lazy electrons are choosing the path of least resistance to ground, and that it may be via your BT setup.
Redo all of your grounds, make sure they are to bare metal.

Scotes 05-08-2008 07:44 PM

Both amps were installed prior to the BT module being installed and they are tied to a distribution block which is grounded to the metal under the rear deck.

Prior to installing the BT module there was no noise in the system - it was only after I put the BT module in.

As the BT ties into the audio system but grounds to a sep location I am going to run an additional ground wire from the distribution block to the ground pin on the 12 pin oem stereo harness (the one that carried the power/ground/woofer connections) to try and tie the grounds together. I just haven't gotten to it yet.

Scotes 06-30-2008 12:58 AM

I tried tying the grounds together but it didn't work. The only thing that gets rid of the whine is removing the ulf. If I disconnect it everything is clean with no whine Only when it is plugged in do I get the whine.

Anybody have any thoughts? Should I try running an additional ground wire from the ulf to bare metal?

This is driving me nuts. Any help would be appreciated. Thanks.

ccfj1 06-30-2008 06:26 AM

Do you still get the whine when you use the VR mode of the ULF, (not when making and receiving a call)?

It could be that the ULF audio out is picking up some interference from somewhere (the amps at a guess), you could try putting a choke of the ULF audio out on the radio modules telephone input pins.

Scotes 06-30-2008 01:00 PM


Thanks for the response. It just dawned on me what the VR mode of the ULF was, duh. I didn't think that when I read it this morning. Anyway, here's some more info - the whine is there whether the radio is on or off and also while making a phone call. I will test to see if it is still there when I kick it into voice recognition but I am thinking it probably will be.

When you say "put a choke on" could you explain that a little better? What would I use and what pins would I put this on?

There are two more things I am going to try:
-I am going to plug the oem amp back into the 12 & 26 pin connectors removing the aftermarket amps from the chain to see what happens.
-My sub amp is nestled in the spot where the oem amp used to live so it is quite close to the ulf. I am going to cut the power to this to see if that is generating something that is getting kicked into the ulf.

The main amp is under the rear deck to fairly well away from the ulf.

Scotes 07-01-2008 02:26 AM

Ok, so I did a little more testing tonight. Here's the results...

- With everything connected I entered VR mode and the whine is still there. The whine is there radio on or off, in VR mode, or in phone mode.
- I disconnected the sub amp which is in the oem amp location and no joy - whine was still there.
- I then disconnected both amps and reconnected the oem e39 amp to the 12 and 26 pin connectors. The whine was still there but very very faint - it was at a level I would be happy with. Down side is the oem amp sounds like shite compared to the Alpine I am running.

One odd thing about reconnecting the oem amp was the level of the amp. I could turn the volume down real low and still hear something. The lowest (or highest; don't know how you refer to it) gain setting on the Alpine is 4v which did not give the same precise control the oem amp gave. It was almost as if the oem amp was running a gain of 5v or 6v.


ccfj1 07-01-2008 03:29 AM

Looks like the noise is being compounded by the new amp setup, I found this, it may help re the amp noise.


Not sure about the gain problems ask over on the e46fanatice I.C.E forum there are some good blokes over their.

Scotes 07-02-2008 01:13 AM

Note there is no noise at al if I remove the ulf module - the noise is only there is the ulf module is connected. I don't think the gain thing is a problem but more of an observation.

Tonight I decided to unplug the rca patch cable from the 26 pin connector to the Alpine amp per the suggestion on the Crutchfield link. No alternator whine. So, it seems that is where the it is picking it up but I don't know where along the line it is grabbing it. The patch cable is cat5 cable with rca jacks soldered on one end and the other is soldered to the bmw leads that go into the 26-pin connector. These have the pins pre-crimped and soldered so I know that end of the pins going into the connector are good.

I'm guessing I should redo this? What do you think?

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