[87Skier]

Just wanted to clarify some information here:

The 4L60/80 uses an external ECM and TCM, so the transmission is told when to shift by applying signals to the solenoids from outside the transmission.

The 6L80/90 uses an internal TCM with an external ECM that communicate over a CAN bus. Correct me if I'm wrong on this, but the ECM sends some information to the TCM, but the TCM ultimately decides when to shift and how the shift is done.

So, when tuning out TCC PWM apply, is this done on the ECM side or the TCM side?