Just to add to this: my 2000 seems to like to eat a flasher relay about every two years. Usually there's 3 or 4 months of it either getting semi-stuck, activating both rear indicators (typically when signalling a left turn), or both, then total failure.
The indicator stalk works in all positions, so I haven't bothered with replacing that yet, but it could be the actual cause whereas eventual relay failure is just the symptom. Throwing it out there as an FYI.