I replaced my car interior light with a Chinese LED strip about 80 cm long, the usual ones with 3 LEDs in series with a 75 ohm resistor. This is the circuit.
The diode helps drop some excess voltage, since the battery provides up to 14V and the LEDs are too bright.
As I marked it in the schematic, the ground are always connected to the car chassis. The long wires are about 1.5-2.5 metres long.
With the car in a dim location, whenever the windscreen wiper starts or stops, but also when I turn off and on the wiper lever without the wiper actually starting because it just completed a wipe, the LEDs briefly light up very dimly.
This happens both with the front wiper (connected to the battery via a lever switch and a fuse, about another couple of metres of wire) and the rear wiper (same as in the front wiper, but maybe 3-4 metres of wire). Both wipers motors are connected to the chassis as ground.
Since the circuit is open, how can that happen? do the wires act as capacitor and briefly charge and discharge through the LEDs after the inductive voltage surge, causing a brief emission of light?