erd = 3rd. Got it.
I'm sure it's the same as on the 2nd gen - the switch is in the steering wheel; you mash it when the blue haired old lady crosses in front of you without signalling.
It could be that your switch contact plate is bent, causing unintentional and continuous contact. You'll have to take the cover off. You'll have an airbag, so be careful. I've never taken the cover off a wheel with an airbag, so someone else will have to provide the necessary steps to take.