Rear fog light hack?
 

I want both sides to light up. DIY?

Two sides lit up look to much like brake lights which is why only one side lights up.

If you do both sides you may have conversations with your local law enforcement officials.

Agreed. It will look as though you're riding the brakes like an old lady.

Duly noted....geritol anyone. Cheers.
 

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Rear fog lights
 

I have a 2015 S60 and both lights are on when said feature is enabled.
I live in Texas by the way.