what is the ect power button by the shifter

Traction control.

How is it used? How is it activated? How do you tell when its off? (I want to keep it off and make sure it accidently is not activated)

There is no traction control on this car. Don't be silly. The ECT changes shift points in the transmission computer. It is sort of a 'performance' and 'comfort' setting. With ECT on the power mode, shift points are higher. It makes a small difference in part throttle shifts points.. almost to the negative. The engine and transmission in this car are perfectly matched and provide some of the best shifts this side of DSG. The 1MZ-FE engine, in 1994, was cutting edge. OK.. VQ is good too, and I know of a few straight sixes that are interesting. What are your valve covers made of? Power braking to load up the torque converter is more exciting than ECT, but beyond the target of this automobile.

I just bought a Lexus and I turned the ect pwr button on then off and now my check engine or transmission light came on why is that