Subwoofer Buzz

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Berf

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The subwoofer behind the left rear seat is making a low frequency buzz sound when the CD player is on. I don't notice it when just using the FM radio. Has anyone else run into this, and if so how did you fix it?
 
Can anyone tell me where the subwoofer amp is located, and what fuse # it is tied to? There are three different fuses for the radio, 3, 11, and 12. Is one of these for the subwoofer amp?
 
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So I found the amp to the left of the subwoofer. It is only making the noise when the truck is running, and it is doing it both on FM and on CD. It sounds like it may be from noise being induced on the power leads and maybe just needs a better noise filter on the power, but I'm wondering if they all made this noise from new, or if there is a problem with a ground somewhere I need to chase down. Has anyone ever had this problem and found a fix?
 
I searched through the service manual and found several references to checking the noise suppression equipment for good contacts, but I can't find any reference that shows what the noise suppression equipment actually is, and where it is installed. Any ideas?

NoiseSuppression.PNG
 
So I guess I'm just talking to myself here, but just incase anyone else runs into this, here is what I've found.

There are two capacitors on the front of the engine, one left and one right. They act as noise filters for the radio. I removed the connectors for both and cleaned them and it made a very slight improvement. Further investigation has revealed that the noise is much louder when the headlights are on with the engine running. So I'm thinking it is simply noise from the alternator (which Ford calls a Generator) being loaded. At this point I think I will determine which wire is positive power for the subwoofer and just install a large capacitor between it and ground and see if that is enough to filter it out.
 
Well, just to close the loop on this thread, I found the problem. Removed sub woofer amp and took it apart. One of the connector pins for the connection to the truck harness was internally broken and not physically connected to the circuit board inside the amp. So rather than try to source and install a whole new connector on the circuit board, I simply soldered in a jumper wire to jump the bad pin and then soldered it to the harness in the truck. The amp now works properly and I have no more buzz. Once connected I realized that the amp wasn't even working prior to this, and probably hasn't ever worked, as it looked like it was this way from the factory.

Oh, and by the way, I have also successfully disassembled, troubleshot and rebuilt the 6 disc CD changer mechanism that was previously jammed as well as fixed the dim display issue, so if anyone wants theirs fixed, I can do that for you.
 
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Its slow here, But cant be impatient either.... Pins break from water or heat on those.... Water from rear window and third brake light leaks are the main cause.
 
The connector pin problem I had was internally inside the amp where it was soldered to the circuit board. It was never connected properly at the factory. I had to take the amplifier out of the truck, and then disassemble the amp down the circuit board to fix it. There was no evidence of water intrusion or corrosion, it simply was not built correctly to begin with.
 
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