standard rear lights - bulb doing nothing ?

[Midlifecrisis71]

Hi folks

My rear lights seem to have a strange 3rd bulb on the lower row, that is doing nothing

My middle bulb is a 5W side light, the inner (Right of middle) one is a 21W/4w which does side light and brake light, but the outer bulb 21W does nothing.

When i put the fog light on, the brake light seems to stay on super bright and act as a fog light but i think this is wrong.

Is the outer bulb supposed to be the 21W fog light ?

thanks for your help
Giles

[Midlifecrisis71]

IGNORE ME - I solved it

I was trying to sort rear lights out on my own - assumed the twin bulb was the brake light, turns out its a combination of side light and fog light, brake light is just a 21w on its own.

Serves me right for not having a mirrored wall on my garage !
I knew the wife was good for something......pushing the pedals!