Had a properly weird thing happening one night this week. When I turned my headlights on from sidelights, the left height adjustment motor moved a bit. With the headlights on, if I turned the left indicator on, it ran slowly, dimmed the left headlight, and set the front and rear windscreen wipers tuning constantly... The only way to them turn them off was to turn the headlights off again.
Fiddled with the wiring around the passenger side lights and it got rid of it, so there's obviously something dodgy in that area with current going to earth or something.