How does this tool work (BMW oil service light reset)?

[tk2014]

Please forgive my electrical system ignorance.

How does this tool work?

http://www.buyandfun.com/en-usd/inspection-oil-service-reset-tool-new-for-bmw-1982-2001-p6824.html

I understand how the hack works....

http://www.bmwe36blog.com/2007/02/24/reset-bmw-e36-oil-service-light/

But the tool??? The instructions say the light will turn off when the system is reset. Do you think the light is on a timer? Or does the tool sense some sort of change in resistance/voltage?

Thoughts?

 

[CO535i]

Prob works the same as this one:

It probably discharges a capacitor that holds the charge for a clock switch in the OBC or something. You have to switch the ignition switch to "on" after connecting the jumper. The ign switch completes the ground.