overdrive

[rider99]

I have a 2007 Yaris sedan with 140,000 miles it has an automatic transmission. My question is that no matter what the outside temp. is here in Louisiana it does not like to shift into overdrive in the morning(worse) or started after 8 hours of rest. I am certain that this has became noticeably different than the previous years. Is there something I should have checked? a/t oil never changed

[tripleyaris300]

This is same as my Yaris with 72k miles on it and on my other yaris with 38k miles. It seems like the computer is programmed so that the engine warms up as fast as possible to reach its normal operating temp to save fuel.

[rider99]

could the thermostat be stuck open?

[Golddeenoh]

the light on your dash goes out at 130 degrees Fahrenheit, normal operating temperatures for internal combustion engine are between 178-215(don't remember exact but around there). our little 1nz-fe appears to go from 184-204(at least that is what my gauge reads) the priority in today's vehicle is emissions first, so the engine has to get warm enough to burn of more toxic gasses. the engine will make that it's priority before it makes fuel economy a priority (i.e. Overdrive) so it is fairly common any more for features to not be available until the priority list is checked off.

oh the 130 should be when the computer takes over full control because the Oxygen sensor is warmed up.

[CTScott]

Both the water temp and AT Fluid temp need to reach a threshold before 4th gear prohibition is disabled. I did some experimentation a while back and figured out how to override it with a momentary switch and resistor. It works perfectly and is very simple to implement:

www.yarisworld.com/forums/showthread.php?t=37691

[daf62757]

When I first got my Yaris, I was concerned but after reading about the systemic process on this forum, I just got used to it.

I don't think I possess the mechanical skills to try and override anything so I will leave it along and just keep on truckin!

[dorman68]

Normal operation. My inlaw's Yaris & my old Echo do the same exact thing.