I have a 1992 250 2 wheel drive automatic with cumming Turbo with 170,000 miles. When cold transmission is not shifting into over drive or going back and forth. When it warms up it seems fine. Also speedometer is reading very slow when cold but seems to go up after warming. Transmission oil is clean, no leaks, no smell, no slipping. I've bought this used and not real familiar. Any suggestions?

 

check trans speedo transducer, might be coming loose, or loose electric connection

 

There is a temp switch that prevents OD from engaging till up to operating temp.
Del

 

Hmmmm? That really seems like whats it's doing? Is that inside the overdrive or transmission?

 

Should be on the cooler line just in front of the trans

 

Also check the fluid in Netural not park .

 

That is the switch that kicks overdrive out if the trans oil temp is over two hundred something degrees F.

One of the parameters is the coolant temp needs to be approximately 60F.

 

Low temp OD cutout switch is in the side of the head just below the air inlet elbow.

 

K thanks for clearing that up why would they put it their tranny heats up faster than the motor in cold weather it does in my new Chevy 1 ton and it has a supercharged gas motor

 

The transmission dumps most of its heat through the engine coolant.

 

Maybe it has something to do with the cumming motor.