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12-30-2019, 07:13 PM | #1 |
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2012 128i mystery noise.
High pitched electronic noise. It seems to be coming from the drivers side/central dash area.
Seems this car has a new issue each week since getting it a month ago. Starts runs and drives fine. The sound starts as soon as the door is opened, though it may be there as soon as I unlock it. |
12-30-2019, 07:26 PM | #2 |
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Last edited by Ursan; 12-30-2019 at 08:38 PM.. |
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12-30-2019, 09:22 PM | #4 |
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No clue, take it to the dealer, I've never heard of this before.
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2012 BMW 328i 6-Speed Wagon | Deep Sea Blue with Grey Dakota Leather | Manual Swap, 330i Intake + Tune, 3.15 Helical LSD, Öhlins R&T
(SOLD) 2009 BMW 128i 6-Speed Coupé | Monaco Blue with Black Sensatec | chris_flies' 128i thread |
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12-30-2019, 09:56 PM | #5 | |
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12-31-2019, 09:20 PM | #7 |
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Might be related. Maybe something isn't grounded right?
Or you could try ferrite rings. https://headlightrevolution.com/radi...reducer-rings/
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2011 135i w/ DCT | ZSP Sport Pkg | PPK | Ohlins R
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01-03-2020, 12:58 AM | #8 | |
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01-08-2020, 07:57 PM | #11 |
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My 2008 135i did something like this when it was new, three or four times. It would last for a couple of minutes then stop. Before I took it in to the dealer to investigate, it stopped happening and never came back. This post brought back the recollection.
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01-08-2020, 08:15 PM | #12 | |
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Then, I re-connected the lamps but put ferrite filters on both cables. The noise was still there. So, I removed the radio. Once I disconnected it from its harness, the noise stopped. I then put ferrite filters on the speaker wires, power wire and both antenna cables. Noise was still there. Then, I decided to put the radio back and I re-connected the harness and wouldn't you know, the noise didn't come back. So I screwed the radio back in, replaced the heater control unit and started the car. Still no noise. BUT, none of my stations came in except for the one in the next town. I turned off the heater and the radio cleared up. It turns out that it's the rear window defroster. So, I'm thinking that it may be the radio that's faulty. Could this be possible? |
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01-08-2020, 09:17 PM | #13 |
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You might be on to something. The radio antennae are built in to the rear window on the coupe (the convert has the rear mast), so if the rear window defroster affects this, there may be a problem with the copper lines in the rear window, or the wired connections to the window. The owner's manual tells us "the upper wires (in the rear window) serve as an antennae and are not part of the defroster".
Last edited by Lester; 01-08-2020 at 09:24 PM.. Reason: Additional info |
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01-08-2020, 09:47 PM | #14 |
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I hope so.
But the question remains, is it the radio, a connector @ the radio, or the defroster or a connector related to that. I don't completely mind if the radio doesn't get all these stations (I'm trying to incorporate my SiriusXM radio using the factory antenna lead) but that noise needs to go. |
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01-09-2020, 05:30 PM | #15 |
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Try removing the fuse that controls the defrost circuit, (I'm not sure what else is on that fuse). If that eliminates the noise, then it's definitely a bad ground or connector that is generating EMF being picked up by the antennae wires in the rear window
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01-09-2020, 07:29 PM | #16 |
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Good thought. If it is the rear defroster, where does one find the bad ground?
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01-09-2020, 08:00 PM | #17 | |
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01-10-2020, 01:02 PM | #19 |
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Wow, you are going to need a shop with a tech that knows how to use an advanced multimeter or oscilloscope to trace this one. Somehow EMF is being transmitted through the radio and speakers from the defrost circuit. You could start replacing wires , switches and connectors (one at a time) but you'll soon run out of time and money unless you guess it right. Perhaps it's in the window itself?
First thing to get would be a Chilton's or Haynes manual (if one is available) and find a circuit schematic. BMW uses brown wires for ground. |
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01-10-2020, 08:40 PM | #20 |
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Interesting discovery today.
On my way to work, the noise randomly stopped. I don't remember hitting anything on the road. It was quiet for about 15 minutes. Then it came back about 10 minutes left in my commute. This time I think I did hit a pavement line that may have jostled something. Before leaving work, I went into the trunk. Everything was dry. No sign of water anywhere. The battery and connections looked perfect. There is what appears to be an amp in the trunk just behind the rear seats. I checked that for loose connections and found none. I even have it some heavyish taps. No change. The sound was still there. During my commute home, I heard some crackling coming from the left rear speaker. I drove over some rough pavement and the noise stopped again. I stopped off for fuel. When I got back into the car the noise was there again. When I got home, I opened and then closed the trunk "vigorously" The noise stopped. The crackling from that rear speaker was quite evident. I shut the car off, waited a minute and re-started. "crackle, crackle...whine...." Again, I got out, opened and then closed the trunk and the noise stopped. It was at this time I noticed what smelled like melting wax. Not burning plastic, but just like wax. So I'll see if I can look at the rear speakers for a wiring fault. I imagine that there's a good video for removing the rear parcel shelf and speakers? I'm getting closer. |
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01-11-2020, 01:16 AM | #21 |
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So tonight I thought it might be either the rear speakers or the amp connections in the trunk.
I removed the rear speakers but alas, no joy. Sound was still there. I'll next need to address the amp. But it was 1:30am and I was getting sleepy. |
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01-12-2020, 02:45 PM | #22 |
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Good news. It's not the HU. It was the amp.
I removed it and cleaned the contacts. I also cleaned and tightened the ground that was there. I reinstalled it and the crackling and the noise is gone. If it happens again, I'll know to replace the amp. |
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