Code U0101, loss of communication with TCM?

Hello, before you go replacing the TCM, there's a Bulletin on this code, but you should first check the connector and harness to the TCM, its powers and grounds as well. If it's missing either power or ground the TCM will just be shut down. I would start by going through all the fuses first. I'll post some diagrams for you, I assume you have a higher end scan tool that can do a full system scan of the entire vehicle. Are you getting any other codes in any other modules? Such as the ECM not being able to communicate with the TCM? And is the U0101 a current code or history code?

The 2 high speed network wires run through the TCM to get to the ECM, but I'm not sure if its a complete circuit on the TCMs circuit board, but the network comes into the TCM on pins 6 and 7 and goes out to the ECM on 37 and 38. There's a couple power feeds to the TCM, the 1st is an IGN VOLTAGE feed from the BCM directly. The 2nd and 3rd are from the TRANS FUSE 4 10amp and the TCM FUSE 42 10amp in the engine compartment fuse block. You can start by checking those 2 fuses and I'll have some diagrams up for you shortly.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Looking at where this TCM is located, I would definitely be concerned about a wiring harness issue. When checking powers and grounds it's best to use a test light so there is some electrical load on the circuit when testing. The powers and grounds need to be able to carry a few amps of load. So, hook the test light to battery negative when checking powers and battery positive when checking the 1 ground wire. If you can back probe the TCM connector to check powers and grounds, use a back probing pin so nothing gets damaged. But it's also good to make sure the TCM connector is not full of corrosion or dirt. Make sure the key is Off if you unplug the TCM connector. The G105 is the only Ground for the control module.

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

https://www.2carpros.com/articles/how-to-use-a-voltmeter

Okay, it really looks like the TCM is in a terrible location, being exposed to the elements and road conditions. Let's see if it's a connector issue. Make sure to clear the code out after reconnecting the TCM harness.

No problem, let us know what you find tomorrow.