Prefer Tom-Tom Start25 to in-built sat-nav (2017 B-Bax, 67 plate) and have hard-wired the Tom-Tom: The supply for the cable is connected to a main ignition supply in the passengers kickwell and is earthed on a Ford earth bolt. All works fine except the unit refuses to power-on automatically with engine start. It powers off ok, just doesn't power-up unless unit is manually switched on. Not a device issue as connecting to 2nd car works fine. Any suggestions gratefully received.