Besides the P1799 code, did you get any other warnings on the Instrument Cluster, or just getting the transmission shifting issues? I just remember coming across a bulletin in the past, where you had multiple warnings on the IC, and you had to go through and check certain pins on various connectors throughout the vehicle, even though it was pertaining to the XJ (X350 ), I do remember having an S-Type that had similar issues, and was able to fix using this bulletin, but that was a one off situation. If you didn't get anything else, then it may not apply, but I can post it up here if you want to have a look.


Cleaning the engine bay is a risk, specially if using water, never know where it will go. You just need to be very careful when filling the trans, you need to do it within the specified temp range, NOT operating temp. Might also pay to check the connector at the back of the transmission to, make sure no loose/bent/backed out pins.

 

"If you didn't get anything else, then it may not apply, but I can post it up here if you want to have a look."

JBz -Yes please, thanks