As was already advised, connect the suppression wire.
However, I did want to note that even with this connected, on some occasions I get 'own ship' indications.
It has always been related to a particular radar service regime. Most recently, Charlotte CLT. I rarely fly into CLT class B but did so Friday because of Hurricane Harvey remains. As soon as I was out, the ownship went away.
This has become more and more rare over the 3 or so years I have had ADS-B.