VESPA GTS Super 125 i.e. Service Station Manual page 158

Injection
Check the presence of fixed voltage between the
grey/black cable of the relay base and ground. If
there is none, check the continuity of the grey/
black cable between the fuse box (No. 3 15 A) and
the relay base.
N.B.
CONTINUITY TESTS MUST BE CARRIED OUT WITH THE
COMPONENTS DISCONNECTED. (RELAYS, CONTROL
UNIT, FUSES ETC.).
INJEC - 158
Vespa GTS Super 125 i.e.