I had asked online and in three different Toyota dealerships and the answers were more or less split whether or not using the ECT button prevented the transmission from shifting into 6th gear. So, I wrote to Toyota corporation and here is their answer. "Thank you for contacting Toyota Motor Sales, U.S.A., Inc. We appreciate your inquiry, and thank you for allowing us the opportunity to respond. We have researched and found the following information: ECT PWR switch- Enhances acceleration performance and responsiveness by controlling the engine output and by changing the shift point of the transmission, thus achieving a sporty drive. Limiting the use of 6th gear when in this mode is a normal characteristic. S mode- Will allow the use of 6th gear however, if the vehicle speed and engine speed exceeds or go below a preset level in response to the driver's downshift operation request, changing the shift range will be prohibited. In this case, the buzzer in the combination meter will sound to alert the driver. We apologize, we do not have a speed diagram for each gear." Your email has been documented at our National Headquarters under file #1908093089. If we can be of further assistance, please feel free to contact us. Sincerely, Sharyce W. Toyota Customer Experience Center Notice how under the ECT mode heading, Toyota states that this mode not only changes shift points (which I already knew) but states that it also controls engine performance (which I had suspected).