Help with Transmission P Codes

The P0740 is a tough one, because it often infers that the torque converter clutch is wearing out as well. You could try replacing the solenoids, which is tough for the ones under neath the side pan, i,e the TCC solenoid, but don't be surprised if the whole converter does not have to be replaced. The communication fault is a code that involves the can bus between the transmission and the engine computers. I would inspect the selector switch, see if it looks corroded, it is right under the battery ( not such a great place ) on the transmission. There are 2 valve bodies one under neath and one on the side. The side valve body is tough because you have to lower the transmission to gain access. after you remove the sub-frame and support the engine from above. Best to have a lift for this type of work.