The P0742 trouble code is related the Torque Converter Clutch (TCC) Solenoid Circuit. Here is how to change it out to fix the problem, please clear the codes when completed. You will need to remove the transmission side fluid pan. Check out the images (below). Please let us know what happens.
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.