Originally Posted by barry
In my truck, with a 5 speed auto, when I push the button to turn overdrive off the torque converter will lock up in 4th but with overdrive on it locks up in 5th so it isn't just stopping the transmission from using a higher ratio.
Barry, do you mean it locks up only
in 5th with the button in overdrive mode?
This is a good point - you can get some programming changes - like with tow/haul - as well as blocking overdrive. Unfortunately, you are also blocking that top gear, even if it might be desirable at times to use it.
My Sienna will lock up the torque converter in at least 4 and 5, and I think 3, even with the shifter in "D" (which means use any of the 5 gears); it does not have a tow/haul mode or "overdrive" button.
Since every transmission and transmission control program can be different, this is a situation which calls for reading the owner's manual to understand what selections are appropriate and what transmission behaviour will result.