Rear bottom right tail light lights up for reverse and brake but not as a running light, just replaced circuit board thinking it might be the problem but the same thing happens, also tried different bulbs, what could be the issue?

 

Where did this "circuit board" come from? It's very easy to trace signals on those cars with a simple test light. Do you have one?

 

I dont see them replying, so i gotta carry on in case it helps me with an issue I have a trace light, how can i check the same thing theyre posting about? I have the exact same problem on a 2006 XC90.