Hi,

Looking for wiring ('circuit') diagram for Karcher WD 3.5 wet and dry vacuum cleaner. Should operate on high or low speed but only runs on high speed no matter which of the two switch positions is selected. Has a simple PC board with only a handful of components on it. Thanks.

Jack Nieman, April 2023

It should be easy enough to identify the main output device and check it for short circuit if you are anywhere near competent to work on electronics.
My money would be that it's gone short.

Rhdbdh, April 2023