yep!

 

I'm going with what I know. The PCM does have it intergrated into it that I know. I don't know of the years and tranies that are affected. Regardless of which, in cold weather it is NOT good to use overdrive on cold or hot transmissions.

Cold transmissions should be warmed up before use and even the owner manual says this. Second if the trans is hot it should NOT be used as a burn up can happen just as well as cold opperation.

All TSB's on the transmission say the same thing.

 

I GOT IT!

Green you use ATF+4 fluids which is Fully Synthetic! Fully Synthetic oil runs like water even when cold. With this a pressure sensor in the trans would not know if it were too cold.

Cold fluid makes it harder to flow thus creating pressure increase in normal fluid.
The pressure increase thus stops the trans from shifting into overdrive because the PCM recognizes this as cold weather or other so as it locks you out. Once you trip it, this will cause this phenomenon. As for the trans coming out of this mode on its own is strange unless the pressures regulate and the PCM cancels the lock.

I am thinking the PCM monitors the pressures and not the actual temperature of the fluid. Most of us are running ATF+3 which is regular transmission fluid.

 

That could be hydra. My wifes car is definitely controlled by the PCM. There is no temp gauge only a thermometer symbol that shows blue when cold and turns off when normal. I imagine it glows red when hot. As soon as the engine temp light turns out on the car it switches into OD.

 

Yes this may just be true, it kinda makes sense as everyone I know says trans fluid loses its density after the trans heats up.

 

Well it come back to regular viscosity. The cold makes it thick and harder to push.

I have been thinking about this all day and night and it has to be right and makes full sense.

 

yeah man it makes sense