The dashboard tail light is on whent it is at night time or when it is dark or becomes dark. Daytime does not happen like this at all. I checked all the tail light bulbs and replaced some that I had doubt on it. The problem does not go away.
Dashboard Tail Light on on 1999 Toyota Camry
If you use the wrong bulb number it will cause the light to come on. It measures resistance in the circuit. If the resistance is incorrect (wrong bulb or bad bulb) it will turn the light on.