App note from OSRAM about different approaches on LED string diagnostic in automotive. Link here (PDF)
One requirement especially in automotive applications is the diagnosis of failures in functions and systems. Therefore light functions realized with LEDs like break light, daytime running light, low and high beam may require a diagnostics function. This application note describes some items which have to be taken into account, when a diagnostic function for a LED string or a multi LED module has to be realized.
from Dangerous Prototypes https://ift.tt/2zGkQ0F