Somebody must have removed the relay during the engine swap and has forgotten to put it back in. I was thinking of this before, but then there should have been at least some leftover wires hanging around. But there were non.
After reading the wiring diagram, opening all of the wire harnesses and found a lot of non-original wires with non-original colors, I measured all the wires from end to end. And it turned out, that those wires for the relay were attached to the alternator and the voltage regulator. 😒 No wonder I did not find any of those wires for the relay. Amazing that the car worked and did not stop or go up in flames.
I rewired everything and tried to go back to the original wire-colors. And ... my horn is back! The buzzer still does not work, but I am not sure, if that is a good or a bad point. . Thank you for your help
