Perform the following test in order to verify: a.) Under the main tab of GUI, type 71 under Send A, 1234 under Send B, and 1 or 2 for Tx or Rx respectively under Send C. Click on Generic Test b.) Type 72 under Send A. leave Send B and Send C as is. Click on Generic Test. c.) Response C is to return -1.

Disconnect inside aircraft antenna cable to bulkhead and verify pins 20 & 21 are not swapped per cable wire diagram.