What is it for

[John Bilko]

I suspect it is to do with the courtesy lighting circuit but there is a grommet in the pillar and would I would like to know its use.

   

[John Bilko]

It has been suggested that the courtesy lights are operated by the door handles? Could that be right?

[brodfather11]

The courtesy lights are worked by the door locks/handles, it may be a redundant hole for the old courtesy light switch