brake warning switch

LED's don't take much current, usually 1.5 V give a visible glow (in the dark). Voltage drops in the common returns could do that. With LED's in my M-B, I noticed the "brake pad worn" lamp slightly glows when raining (visible at night). It normally lights when the sensing wire in the pad touches the rotor. The slight conduction thru the water is enough to give a slight glow.