The left rear signal doesn't work. I check the bulb and it is OK . I changed the bulb anyway and still doesn't work. I swap the socket from left to right and the socket work fine.Front signal work OK. I check the contact at the socket and it looks fine. Please help. Is there signal flasher? Does to whole tailight wiring ba. I try to move it around just in case the contact got loose but still not work.

It is for 2003 S500.

Thank you