Yeah I think it's on the circuit board that's in the dash/instruments, may be not even a relay as such. I was looking to change it when fitting LED indicators but couldn't find it anywhere and a post on ADV said that it was built into the dash. I've fitted resistors left and right to the front LED indicators but not the rear LEDs. Both front and rear flash at the correct rate now.
Sent from my Nexus 5 using Tapatalk