P0740 code looks like a wiring problem or mechanical?

This seems like an electrical problem, specifically the torque converter control solenoid which is bad and shorted or the wiring inside the transmission is shorting to the case or you have a shorted tog round exterior wire from the PCM but chances are the solenoid is bad and need to be replaced.

TCC Enable: NO
The PCM is not commanding the torque converter clutch to lock.

TCC Duty Cycle: 95%
PCM is trying HARD to apply the TCC (95% command = full apply).

TCC Slip Speed: 345 RPM
The clutch is not locking, tons of slip.
But this could be because the apply circuit never actually energizes.

Brake Switch: CLOSED
This means the PCM thinks the brake pedal is being pressed.

TCC Enable open/short to ground: YES
This is the problem.
The PCM sees a fault in the electrical circuit that enables TCC apply.

Please let us know what happens.