Trying to get some insight as to what could be causing transmission issues with my mother's Cobalt. Here is a video -


In short the car is going in and out of overdrive. At 60mph the car will constantly jump back and forth between 3rd gear and overdrive (alternating 2000, 3000rpm).

A side note - If you put the transmission in the highest gear (not D) the car won't shift into 3rd until the vehicle is at 45mph regardless of driving conditions.

Any help or guidance would be appreciated. I'm electro/mechanically inclined but don't know where to even start.

 

[edit] The only code we are getting has something to do with evap and seems to be fuel cap leak related.

 

The vehicle is still having the same issue. Can someone give me an idea of where to start with diagnosing? I hooked up the Torque OBD app and that didn't help at all since the GM Pid library doesn't have any of the data I would need to diagnose transmission issues.

Any guidance would be appreciated. I cleaned the electrical connectors at the fuse box. This didn't help or hurt the issue.

 

How many miles? Have you checked fluid levels? Have you changed it before?

 

Fluid level is good. Since my first post the fluid was replaced and the behaviour of the transmission did not change.

The issues started around 100k miles.