Wired ground wires for stick grip wiring. Used GAD27 dSub pins 28 and 30 (wht/grn) that were originally for the roll trim servo (not installed). Tied the 2 wires together and extended with a third wire using a solder sleeve. This ground wire will be attached to the main firewall grounding block. Discovered error in my wiring of dSub plugs to stick grips. I unpinned and reversed the wires in the male half of the connector to match up with the female connector. (you must be aware that the male and female dSub plugs are mirror images of each other- pay attention to the plug wiring numbers!) Plugged back in and powered up Avionics. After temp installing the headset jacks and headset, I tested the PTT- they work perfectly for both stick grips and both radios transmit from both left and right grips. I also connected the new USB-C power cord to the iPad and it works as expected. The iPad cooling fan also works as expected I also was able to verify voltage on the Avionics IBBS @ 13.8v. In addition, I was able to receive an ADS-B target on the transponder (also appeared on the G3X map display) while still in the shop. Also, I was able to pair my phone to the GMA 245 via Bluetooth and listen to music over the aircraft headset. Way cool! Finally, I verified the V-speeds that I loaded the other day into the G3X. They speed tape has correct speeds and color bands. Testing will continue but I'm very happy with the results of the Avionics testing so far. Again, I'm using a 14V. regulated power supply wired directly to the main bus.