Rear fog light zero volts?

My 1993 k11 was in need of sanding ground points, replacing the tail light lamp holders and checking out custom wiring which came with when I bought my car. Probably annual inspection does not require to have a working rear fog light since it wasn't mentioned. But I'm planning to use my Micra as daily driver. My job requires me to drive my car trough a great part of my country and that at times that bad weather might occur.

But I have zero volts on my rear fog light and the front is working. I checked my fuses but I wonder from here, how to start fault checking with a multimeter?

Or even better does someone recognize this as a malfunction that is known to the k11?
 
I did not consider looking at the fog light switch as a piece of simple electronics. So you say the fog light switch switches two plus wires and might be working half? That would be a bad case if both of my cars have a faulty fog light switch, those switches are not common.

I will measure the wiring to the taillight, I should have been able to think of this of my own but now you have pointed this out to me, it would be a surprise if it is something else I suppose. But I'm curious, this is the first time I have many electronics issues with a car so the hands on experience is appreciated by me.
 
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