Carlights

My german is not that good that I can write it, but I understand it well. That well that I come visit this site at least once a day.
I do own my fabia combi 2.0 now two months. I drove 8.000 kilometers with it. But now I have a question.
When the motor is getting warm (with temperatures outside from -5 to 10 degrees, after 3 to 8 minutes), and I stop for a traffic light, I hear the sound of an switching "relais" and the carlights seem to get less brighter. Does anybody knows what this is causing?
It does not make any difference if there are things turned on that consume power, also the on/off position of the airconditioning does not make a difference.
I hope to hear from you. And if you don't mind the Englisch language, I will post some more questions and answers in the future.

Groeten van Michel uit Holland.

 

Hallo Michel,
ich habe das Geräusch des Relais zwar noch nicht gehört, bemerke aber ebenfalls bei meinenm 1,9 PD TDI, daß das Scheinwerferlicht bei Schiebebetrieb im 5.ten Gang auf der Autobahn, d.h. in Situationen ohne Gaspedalbetätigung, z.B. bei Rollenlassen vor einer Baustelle, schwächer wird. Es scheint als ob die Lichtmaschinenleistung gedrosselt würde. Technisch kann ich mir das nur durch niedrige Motordrehzahlen erklären...?!