•1st verify that the TAS is a 9900BX or TAS6xx

•The 9900B units will not work.  Ever.

•GTX345 turns the TAS audio volume to 0, and will not let it be adjusted while the GTX345 is powered on.  This is part of the issue.  If the audio is not connected (per Garmin) or the audio volume is stuck at 0 (per Garmin) there is currently no easy way to determine the fault code.  

•What you can do is scab in an aux audio jack connected to the audio +/- coming off the J1 connector.  Then using an aux cable run to a stereo one of the techs has on his/her toolbox, and you’ll be able to get the audio callout, but only after turning off the GTX345 (by pulling the CB) which will allow you to set the volume to max via the CVI menu.

•Another HyperTerminal option that is useful is instead of entering “CVI” or "NewCVI" enter "newric" and Com ports can be checked via option "C".

•When interfacing a TCAD-9900BX/TAS-6xx Active Traffic to Garmin GTX-345 ADS-B IN Transponder, the existing "NO Avidyne DISPLAY" GRD jumper, J1-15, needs to be REMOVED.  The Garmin GTX-345 emulates the RS-232 Control Data of an original Avidyne ATI-150, 1/2 3ATI Indicator/Controller. This is especially important when changing the interface from a Garmin G1000 System where the initial control is over Arinc-429.