Friends, thanks for all the excellent advice. I will check all the things mentioned. @Nippy I'm sorry, but I don't have a Windows computer with Protune, and if I had, I'm not so good with computers, so I'm not sure if it would be of any help.
I've collected some courage and will start searching again to solve this problem.
I see in the parts book five ground connections at which the two looms are connected to the chassis. I've found one under the bonnet just behind the engine. From the drawing, it looks like the speed sensor has earth on that spot. But does anyone know where to find others?
I also see three wires in the chassis loom drawing at the speed sensor. YB and YR both go to the engine/chassis connector. Does anyone know where the YK go to?
