SL500 W230 - radio interference

[dickb]

Have a 2002 SL500 and as soon as I turn the ignition key the radio picks up some interference. It isn't the aircon fan or anything else I can hear. It is constant too and does not vary with speed. Does anyone know of a motor that runs as soon as the ignition is turned on.

Many thanks

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[Sp!ke]

Do you have anything aftermarket running in the car?

Maybe a non standard head unit or dashcam or something?

 

[dickb]

No aftermarket stuff apart from a Bluetooth phone Parrot. It sounds like a motor running somewhere at a constant rate. Very strange.