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Discussion Starter #1
Hi everyone,

I have a bit of a puzzle with s strange and intermittent noise coming through the radio and wondered if anyone had experienced anything similar......

OK, basics are I have a 2007 CRD. I wanted Apple car play so fitted an after market Pioneer head unit. I used the PAC wiring kit to make the connection. The radio plays and functions fine.

From the outset though I have been getting a strange intermittent noise from it. It comes as a high pitched scratchy whine that only seems to sound through the front nearside dash speaker... Some specifics -
- It is not there all the time, and can sometimes be silent for a couple of days.
- Sometimes it comes on as soon as I start the car
- Sometimes it comes in gradually, like someone turning up a volume from silent, and sometimes it goes away the same way
- Sometimes it comes and goes quickly like someone flicking a switch.
- Sometimes it seems to come in at 'half volume' and stays there.
- It stays constant regardless of engine or road speed and does not turn down with the radio volume.
- I sometimes think it is influenced by bumps in the road, and sometimes I think it going off coincides with braking.
- The only other modification I have made that I thought may be a factor is replacing all of the interior lights with LED's I mention this because when the noise is there, switching on an interior light introduces another additional lower level buzz to the sound.

So far I have two theories, based on no knowledge whatsoever -
1. It is something to do with the control box in the PAC wiring room which is moving and causing the noise when it is in a specific position, or
2. It is to do with the LED lights in some way, although the lights being on or off doesn't seem to cause it to start or finish.

I have tried searching on this site and else where on the net and there seems to be a link to LED lights and interference but that seems more like headlights etc. Sound clips of that does sound very similar to what I am experiencing though.

So - any experience or suggestions??
 

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Discussion Starter #3
Thanks Big Blue - that makes sense. I've been waiting for some decent weather to pull out the dash etc again to have a look at that control box, so I will check this at the same time. I used the original ground connection from the factory head unit, but it could be the connection between the old and new isn't as good as it should be.... I will report back!
 

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Thanks Big Blue - that makes sense. I've been waiting for some decent weather to pull out the dash etc again to have a look at that control box, so I will check this at the same time. I used the original ground connection from the factory head unit, but it could be the connection between the old and new isn't as good as it should be.... I will report back!
Looking forward to it.
 

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Discussion Starter #5
Sorted!

Decent weather today so I pulled out the dash panel and the new radio. There's a lot of wiring in there due to three components -
  • Wiring on the new head unit
    • The PAC connecting loom
    • The original vehicle loom that connected to the factory head unit
I started moving and testing all of the connections and despite my original issue being a noise through the passenger side speaker, I moved a connection and it came through the driver's side... Exactly the same noise though, so the first indication that my electrical work was not all it should have been. I fixed the connection and moved on to the passenger side and moving the wires was able to generate the noise. Fixed that one too and tested all of the other connections while I was in there. Total time spent from unlocking to relocating the doors probably only about 60 minutes.

Lesson? Well, I thought that the noise was being generated by either an electrical component moving and causing interference or alternatively a bad earth (ground). I would have thought that a loose connection to a speaker would have caused it to cut the sound intermittently, not generate a high pitched buzz.....
Every day is a school day it seems!:grin2:
 
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