To make this determination, remove a headlight motor control relay from it's socket and set it aside. If both headlights are affected, it does not matter which one you choose for this test, otherwise, choose the defective one of course. The motor should run and the headlight should cycle repeatedly between up and down. If not, while the short between pins 30 and 87 is still present, measure the voltage on either pin. Be sure to spray the fuse spring clips with contact cleaner and rotate the fuse in it's clips a few times.
European fuses are notorious for corroding into high-resistance connections.
Also, remove the fuse block and remove the wiring push-on terminals associated with fuse S12 one at a time and spray the contact surfaces thoroughly with contact cleaner. If the terminals are loose on their male flags, squeeze them slightly with pliers to restore proper fit. If the motor runs with terminals 30 and 87 of the relay socket shorted, the problem is in the control circuitry. Remove the short between pins 30 and 87 of the relay socket, and then install the relay. V. Now, turn on the ignition and the lights.