Brake wear indicator - How do they work ?

[bilabonic]

Just whipped wheels off to check all sensors/pads and all looks fine.

I disconnected the plug going to the sensors on each wheel and metered them and they are all short circuit/zero resistance as expected.

Is there another point i can check on the car after they have all been series together ?

I also noticed another plug directly next to the brake sensor plug, it looks as if it's going into the hub, what is this for ??

Totally lost now peeps ??

Cheers