I am trying to complete the installation of my ADS-B 600B. I plan on using the Serial #3 on my 4500 for the serial communication.
When I removed the cover on the DB-25, I find that Stein has made the Serial #2/#3 ground splice very close to the plug. Trying to splice in my ground will not be easy. So this is the background to my question.
Internally, are pins 9 and 21 common? It would be easy to splice into pin 9 to pick up the ground for my serial #3 if in fact they are common.