VESPA GTS 250 I.E. Workshop Manual page 194

Injection
With the control unit and the injector disconnected,
check the continuity of the Red-Yellow cable be-
tween pin 14 of the interface wiring and the injector
connector
Switch to "ON" and check the presence of voltage,
with injector disconnected and control unit con-
nected, between the Black-Green cable of the in-
jector connector and the earth
INJEC - 30
Vespa GTS 250 I.E.