Transmission Troubles P0777 and P0700

[Max Lupfer]

Today while moving some furniture i had a really messed up downshift in my truck and while coasting to a light. After that the truck would not go higher than 4th gear on the highway and the check engine light came on. When i got home i checked the DTCs and P0777 and P0700 showed up. Id like to get an idea if it is the solenoid or signs of a different problem. The truck drives fine other than not being able to go past 4th. 

 

Truck: 2003 Chevy Silverado 2500 HD 8.1L, 90k miles, trans fluid and filter replaced within 5k miles.

[davester]

The P0700 code is just a generic "the tcm is telling the pcm that there is a problem with the transmission code, and to get the specific code from the tcm itself" code.  Looks like the P0777 is from the tcm, so that should be the only one you are concerned with.

 

Go through the diagnostic procedure for the code.  Googling for it will list a bunch of things to test to figure out where the problem is.  If you want more specific info on the diagnostic procedure for it, I would suggest signing up for the full-service manual for your truck at a site like alldatadiy.com  (vs the more generic diagnostic info you get from google results).