how does this work and how to build it?

Hi guys,

I was wondering how would a car MCU know if the tail Light fails etc...??

i was thinking of a construction with a mosfet and a light in series then measure the voltage on the snd side of the light will it work???

Question 2, how can i switch a light with this mosfet?
part number: UCC27322P Texas Instru.

hope sone one can help

TKS

They either use a resistor and read the voltage drop, or have a hall effect sensor beside the wire to sense the magnetic field from the current. I think the second may be the one used, but I'm not sure.