Transmission gear problem, transmission suddenly lost third and fourth gears?

Hi,

This type of problem can be caused by several things. It could be a line pressure issue, an issue with a shift solenoid, worn clutch plates, an electrical issue, a plugged transmission cooler, or even low or excessively dirty transmission fluid.

What I recommend is to have the can-bus scanned to see if there are related diagnostic trouble codes.

The acronym CAN stands for controller area network. Basically, the different modules on the vehicle communicate with each other via a few wires (CAN). This type of scan will help narrow things down if codes are present, and they should be.

Here is a link showing how it's done:

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Let me know if this is something you can do or have done. Also, let me know if you have other questions and if the transmission fluid is both clean and full.

Take care,

Joe