SL/R230: Static noise
Chances are whatever the problem is, it is showing itself as a magnetic field. Get a compass. Pass it close to all body (inside and out and under the cars body) areas during a time when the problem is particularly loud. When the compass gets close to the magnetic field, it will go a little goofy. That is one possible source. Put a felt tip marker mark on that spot. (if you have multiple suspect locations)....Then go to the next one. Later on, when things dry out and the noise is not present. Do it again at each marked spot. At the one spot where you had a compass reaction before, But DO NOT have a reaction now, that is likely the area where this problem is going to be.
Magnetic fields of this type can come from improperly grounded, our errantly grounded currents. Or poor connections, or chafed wires or circuits. Some circuits can be in wiring harnesses, or inside of electrical components or housings. Those are the tough one to find. But check the component with the compass. If you cannot get inside the component to make a repair, you might want to replace the component if cheap enough. If it is an expensive component, consider sealing it tightly against humid conditions.
Let us know how you make out.



