On my 2010 lmm while checking codes this one U0100 ( loss of communication with tcm)
What can cause this code to come up?
I never noticed anything different in the way the truck shifted.

Also my edge insight would not read the code but hypertech did, and I never tried ppe as the programmer is sent out to get dpf delete added to it.

A tuner or combination of tuners was in the ECU and it tripped off to that code to protect from more bad things going in. The truck needs to be reflashed with a stock tune and only use one tuner. If another tuner is vin locked on the truck trying another tuner will make this happen at times.

Truck was on stock tune and the edge has no tuning gauges only.
What else could cause this code.