Recently I’ve been firing up all the avionics systems and testing everything that I could. This included testing receive and transmit on both radios and with both headsets. Turns out I can’ transmit on the pilot’s headset. Whoever installed these connections, clearly messed something up. Sure enough, upon inspection, I had reversed two wires. The crazy thing… You can see where I had them correct, and then reversed them. So somehow I had them installed correctly, got confused, reversed the two wires into the wrong position and completed the installation. Regardless, I fixed the connection and all is now working with both radios and both headsets!!