Transmission will not shift into 3rd gear and code P0700 is present "Mil request". Now the crazy part is if the truck is turned off and back on everything is fine and shifts normal until out of no where just like its got a mind of its on it will no shift. This has happened after 20 miles or after several 100 miles. The transmission was rebuilt back and January and has since had 52,000 miles on it. the guy who rebuilt it can not figure out the issue is.
Anyone have a idea of what the issue could be?

 

Thanks for all the Help

 

I get codes like that and shifting problems when the battery voltage has gone way down such as after mine has been stored for a while. Check your batteries and replace them if they are old... Even if it don't fix this issue it will prevent other ones...