Wipers not working

Hello. My Denali has an issue with the front wipers. The wipers will only work on the highest setting. All low to high inputs through the turn-signal/wiper switch do nothing, also the washer spray will not work when turning on via switch. I have replaced fuses and a relay for the wipers and washer, installed a new wiper service/turn signal, new wiper control board followed by a new wiper motor with another new control board, spliced on a replacement wiper motor connector, and tested wipers with a different BCM (without actually starting the vehicle) and I still have the same issue with no changes after any of these repair attempts. When the problem first appeared I also had no park for the wipers but that issue was corrected somehow along the way.

The problem presented itself after I installed a aftermarket stereo, I ran the switched voltage for the stereo from the wiper fuse inside the car. I'm not sure if something happened from that stereo install to cause this issue, but I have made sure that I didn't pinch any wires in the area the stereo is installed in. I have done a lot of wire continuity tests to check for breaks in most wires from the switch to the motor itself and haven't found any. Is there something I am overlooking? Any help or advice is greatly appreciated. Also if anyone can provide me with normal voltage and resistance readings at the motor connector it would help. Thank you in advance.