The P0700 code is a generic code stored in the powertrain control module (PCM). The PCM receives a message from the transmission control module (TCM) of a problem. That sets the check engine light to turn on and have you further investigate.
The P0720 is related to the output speed sensor. However, it could be a wiring-related issue or an issue with the TCM.
The P1790 is a code that indicates an issue immediately after the transmission shifts. This code could be caused by a fluid-level issue.
That leads me to a question. When you checked the fluid level, was the engine running, at operating temp, and was the van on a level surface? If so, in what condition is the fluid? Is it still a pinkish/red color or is it dirty or have a burnt smell?
Let me know so I have a better idea of which way to direct you.
Tuesday, November 21st, 2023 AT 9:19 PM