So all of a sudden when I use my blinkers signal lights on my tail light both tail lights blink.I changed the light bulbs checked the fuse box and relays Idk what the heck is going on here with my 04 G35 COUPE

 

very strange. You wouldn't happen to have trailer wiring would you?

 

Mine does the same thing. Did you get yours fixed? Was it the BCM (body control module)?

 

That was the OP's one and only post on here so I doubt he'll answer you. Great job of searching though, thanks.

 

Hi there. This is what the dealer told me my issue is in my g35 coupe 2004. He quoted me a $400-$600 job. I bought a plug and play tail as turn module and it only fixed my rear blinking issue during the day when the tail lights aren’t on.