P0741 Audi A4 3.0L 2004 Where are sensors for the clutch solenoid valve -

Question

Everyone talks about the torque converter. Isn't the best starting point to determine if solenoid is operational. I would assume if one was to apply a voltage and measure the current, one could determine if the solenoid, harness, connectors are functional.

Where can I obtain a wiring diagram and location of the components?