Solenoid and over drive issue replaced solenoid in trans fixed over drive issue but now its back. Going to buy a new wire harness but maybe there is a short? Or bad ground? I'm not good at electrical just bought a volt reader

 

You will need to do practicing and heavy reading to get familiar with your meter. Then you will need a wiring diagram to determine what components are involved. If you are determined to learn, all the power to you ! Just when you feel you have isolated the problem, be careful because an intermittent problem can drive you to drink.