Help understanding please

[Diver300]

Take a look at the schematic, it IS a single wire

What I meant was that it isn't possible with a single wire where there is only an on-off function on that wire.

That is why I think there is a more complicated signalling system.

 

[Don Wright]

Here's a wiring diagram from shopkey , theres no body computer in this circuit unless that's what your calling the relay panel?? Hopefully this will help sense your other diagram isn't very good.

 

[shokjok]

Fuse F52 is irrelevant in this drawing, and M56 relay contacts can be jumped to test the wiper motor.