Doesn't it work like this? I think so. My 4 pin Bosch is the same as a 3 pin. 30 and 86 ARE tied together. Horn relays are different. Bosch did not have horns in mind really. if they did, the relay would have 3 pins like the old unit. But it is designed to be switched by power or by ground. We use it in ground switch mode for horns. It needs 4 pins to use in power switch mode. As you know you can turn a 5 pin into a 4 pin, which is really a 3 pin when used in ground switch mode as Lumbersawyer did by abandoning one leg (the normally closed leg).
Don't see any grounds to relay mounting feet yet.
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn
