Replaced automatic transmission with used transmission and torque convertor. Upon initial start, truck will shift gears, but wont move unless i rev engine to approx 3000 RPMs. But then it only moves at a very slow pace. Code scanner reads P0740 only. No other trouble codes listed. Manual indicates this code is the torque converter clutch circuit malfunction.

Can you please provide your feedback on the problem? I am unsure where to start or how to troubleshoot my issue. Is this a torque convertor problem or a wiring issue? How do I fix this problem.

I appreciate your help tremendously