I don't want to hijack this thread, but concerning radio receive with (Sigma) 4/4 I have to tell my 2 cent. If anyone is wondering if the receive of FM could suffer of quality I had a weird experience I will share to give you the opportunity to enhance your receive. My radio got worse and worse in terms of receive quality. I thought at some point I should change it. Then the fuse of the wiper blow, one, two, three times in more shorter periods of time. I discovered, that the connector/switch of the wiper motor was the culprit. And the funny thing is it was the culprit for both symptoms. The fuse blow and the bad fm receive.
To make a long story short (and now my English ability runs out) the connector/switch is a white plastic part which is monted at the wiper motor. If you disconnect it you can see a pushbutton switch which is controlled by a kind of mini camshaft. This works to have a start and stop point for the wipers. The system is permanently under voltage. If the pushbutton is pressed by the cam, the wiper stops. But...this pushbutton is not pressed to the end. This can cause a kind of sizzle which a) makes load to the fuse and b) disturbes radio receive to a point of no station can come in. On AM it is even worse and sounds like a drilling machine.
Two weeks ago it was worse but we wanted to drive to Italy. So my son had the idea to extend the puchbutton with some glued plastic. The radio receive was better than ever and the fuse hold. After returning from Italy my Kind dealer replaced the whole wiper motor on guarantee (because the switch alone is not to get). The funny thing is that the wiper fuse keeps until now, but the radio receive is worse than under the improvised repair before. In other words the pushbutton is not working as it should even when new.
To check if your radio receive should suffer on a Sigma 4/4, just compare the receive quality between two key positions. Engine always out with ignition vs. without ignition. Put the radio on AM because it shows the issue instantly. If you hear a drill machine but no music when ignition is on your wiper motor pushbutton is the cause.
