I have a 4R70W and the 3rd and OD quit operating at the same time while I was driving. No shudder, grinding or noises just working one minute and pulled away from a stop up to 40 miles an hour and no shifting. 1st and 2nd gear r fine.
I did get codes on my OD switch but I accidentally erased them. WHen removing the transmission I pulled the TCS wiring harness and the inside of the switch was full of fluid. no way it got in there except from the pan side. wondering if the switch is cracked internally and fluid is being forced into it. Could that keep it from shifting properly and if so can u tell me how to remove it or check it? I appreciate any help u can offer. Really cant afford to rebuild and if it is just the switch I think I can handle that.

Thanks in advance!

 

What's a TCS switch?

 

It is the "Transmission Control Switch". The main wiring harness connects into it on the passenger side of the transmission and on the inside of the transmission it has a plastic strip connecting it to the solenoids.

 

The TCS (Transmission Control Switch) is the OD OFF button on the end of the shift handle on the steering column.

You are describing the wiring harness to solenoid body connector. The part inside the transmission is called a molded leadframe connector.

To remove the solenoid body connector from the transmission you have to remove the pan and remove the connector from inside the transmission.