Tom by TomTom blinks green every ten seconds to let you know it’s connected to your phone.
There is a setting for this in the Main Menu of the TomTom app > Tom > Sounds & lights > Green heartbeat.
You can also check the connection in the TomTom app:
Open the TomTom app on your phone.
Tap the Main Menu icon in the top left.
Check if Tom states Connected or Update available in green font.