If I am in the car, it's the left head light. In the picture, I am in the position 0. If I change position in "side light" position or in "low beam" or "high beam" position, both drl are working with less intensity (normal way of working).
hmm........ most certainly try @ZERO815 suggestion (bad earth connections can cause really odd problems!
BUT if the problem with this car is as OP describes in the quote above (i.e. the fault changes with variations in the rotary switch position) and if the DRLs work OK sometimes - then maybe this is a control issue rather than a wiring matter?
Nevertheless, a strange problem indeed!!