What is the problem when my 2006 GMC Duramax is showing engine codes U0100 and P0700

Question

No codes were shown when I shut off the truck. The next morning when I started the truck the check engine light stayed on. I plugged my code reader in and it gave the codes U0100 and P0700. I had noticed that the truck seemed to be shifting funny the night before. What do you think the issue may be?

Answer 1

U0100 Lost comminucation with ECM

P0700 Transmission fault detected

With U0100 try this for a fix,go to driver side under the frame area there is 2 power ground about 12 gauge clean and secure the connections, As for the P0700 it should be accompanied by another P07XX code.