I just did a remove & replace on my engine, a 5.7 hemi. I had to do the same thing 1 other time and after the 1st time everything went together with no issues.

But this time I'm having issues out the wazoo. All of them have to do with the transmission. I've had a couple of codes pop up but they have both disappeared.

Now, my transmission has decided that it wants to slip up out of gear when I just put it in Drive. But when it's shifted by hand it drives just fine.

The last code that popped up was a p0700. Something to do with the TCM, whatever that is. I should also mention that the fluid has a brown tint to it and it doesn't smell the way it should.

I got this truck back in 2021 and it drove just fine even all the way up until I messed up this last engine. I haven't even driven this thing but maybe 3,000 miles since I got it .

But all of a sudden it wants to do this. Any ideas?

 

0700 is a general trans fault code, usually there is at least one more code that accompanies it.
TCM is the Transmission Control Module.
Sounds like a self inflicted casualty. Wires get pinched on a reinstall very easily.