Automatic transmission electronically is not conneted to speedometer both are electronically out-car runs fine. I know it is an electrical issue but I checked the fuses and all look fine except there are a two fuses that you can not tell if they are blown other than the things that they run are still working

Your speed sensor is giving out I believe. The transmission is fine, I'm very sure of it. So in short: It's electrical!

FYI: When the speed sensor signal is not reaching the computer, it doesn't know if/when to shift gears, or what gear to even be in. That's my basic summary of why this happens. There could be more to it than I know considering it's a newer car... but I think I'm right about it being a speed sensor.

most likely but I am not exactly sure what ones other than shift connections and speedometer sensor(etc)

A speedometer shows speed, which is the magnitude of velocity. It does not show velocity, which is a vector, meaning it includes a direction. So speedometer notworking have nothing to do with the transmission not going into overdrive. Know more diagnostic tool for car.

Sounds like the sending unit to the speedometer is failing. This causes the speedometer to jump around and confuses the heck out of the electronics that controls your automatic transmission.

that year has an electronic speedometer which runs off of a vehicle speed sensor mounted on the transmission, the same sensor tells the computer what speed the vehicle is at and allows the transmission to shift properly

Cheapest scenario is to change the transmission filter. That is if it is an automatic. When you do this, most transmissions have a magnet in the transmission pan. If yours has one I would check it for excessive metal shavings or worse metal chunks.

It maybe your speed sensor. Which is mounted on the transmission by one bolt. It should be near a cv axle (I would imagine). They run anywhere from a little over 100 to about 220.

Check fuses. The speedometer works off electronic signals, it is common for several indicators, like the brake light and abs signal to work off the same fuse. Check your owners manual for fuse panel location and fuse identification. Don't be surprised if you experience strange transmission shifting while this fuse is out as well. Without the speedometer signal the transmission doesn't know when to shift properly.

You just have a bad vehicle speed sensor, has three wire's going to it, sit on top of transmission between transmission and fire wall on top of transmission, held on with a 10mm bolt.Depending if it's manual or automatic transmission the part will cost any where between $70.00 and $160.00.Hope this was very helpful.

Your car has the 125c/3T40 model trans,3 speed automatic with lockup.When you say you unplugged the "speedometer",if you are referring to a square electrical connector on the trans,facing the radiator,that connector is not the speedometer,but the lockup circuit inside the transmission.It is likely the lockup solenoid inside the side pan has gone bad and is malfunctioning.It is a common problem on those transmissions.You will lose some gas mileage by unhooking the connector,and eventually,years down the road,will hurt the trans from the fluid running too hot.Lockup clutch application in a General Motors lockup torque convertor helps to cool the fluid.