ok so i searched and searched to find a answer or a solution but couldnt..... sooo both rear fog lights and right tail light are very bright and workig fine but my left tail light seems so much lighter then the others could this be the bulb or maybe the wiring?

 

so no one had ne idea?

 

this is bulb problem, try exchange the bulb (from left tail light to right tail light and vice versa). and see what's happen.
is right tail light still very bright?

 

A little info helps what kind of car do you have?

 

sry its an 02 a6 2.7t

 

Try the method "andry" suggested. If you are still having an issue, you probably have a wire grounded somewhere. Then you will need to follow the wiring to see if you can find a ground issue. I hate electrical problems. Good Luck!