It’s leakage or monitoring current coming from the control module.
That same current was always going through the original incandescent bulbs.
(Those little interior bulbs are not halogen BTW.)
There is no additional drain with the LEDs.
Unlike the halogen bulbs, LEDs remain fairly efficient down to extremely low currents; 1% of rated and less.
I just lit a small incandescent bulb (#47) on my workbench as a test.
At 50% of it’s normal current it was down to a dull yellow glow, at 30% current a barely visible red glow.
An interesting possibility with household LED bulbs is doubling as night lights when switched off by placing a capacitor (0.1-1uF with 120V 60Hz) across the switch so the light does not go completely out.
Consumption can be 1W or even less.
