both lights should come on when you start the car, this is a self chack and then they should turn off. I beleive if they stay on it means there is a problem with the system and the computer disabled it. sometimes when it is really wet the lights will come on in my car, I think it is some bad wiring someplace, or the plugs, normally a restart of the car makes the lights go out. I have notice no ill effects of this either
