Most likely culprit would be a bad shift solenoid. Take your car to a parts store and see if they can find any codes with the code scanner.
what would transmission not to shift in to overdrive
Overdrive means the wheels are turning faster than the engine so gas is saved, (5th gear would be overdrive) however if you want to accelerate quickly you will have to shift into a lower gear which would make the engine turn faster than the wheels.
Same as any engine. If your gear shift is moving as well it will possibly be your engine mounts. If its been happening when cornering check your drive shafts.
If your 1997 Chevy diesel will not shift into overdrive, you might have an issue with a transmission sensor. Some of these vehicles have several sensors that must engage in order to shift.
If the overdrive switch is turned off then the car will not go into overdrive. As it is not in overdrive, then it will not downshift out of overdrive as it normally would. It also will not shift to 3rd gear above a certain factory preset speed. Turn th overdrive on and see if it operates normally.
Linkage adjust
Your transmission might automatically shift out of overdrive while driving on the interstate because of low transmission fluid. This issue might also occur because of a bad transmission sensor or overdrive sensor.
There is a push button on the end of your automatic shift lever. Pushing it in causes the Overdrive to turn on and off.
bad filter and fluid,bad front pump,or the overdrive is going out common problem when using overdrive in the city limits meant for the highway start and always stoping not good to be in overdrive cant stress enough here at the house until she spent $3770.00 dollars dont have to tell her anymore
Even after pushing the overdrive cancel button again ? to allow the overdrive feature On my Ford Explorer with the column shift automatic , the overdrive switch is on the end of the gear selector lever
what would cause a no start condition when engine spins in a 95 taurus sho 3.2l
The same thing happened to my dads 96 Chevy S-10. The transmission was rusted not allowing it to shift. I would have the transmission checked out.