VESPA GTS Super 300 ie 2008 Service Station Manual page 214

Injection
Check the 15A Fuse No. 3
Check if there is +12 V voltage between the GREY
cable of the electric fan remote control base and
the ground connection.
Check if the RED - BLACK cable between the fuse
box under the seat and the fuse box in the glove-
box compartment is not interrupted.
Check if the GREY cable between the fuse box in
the glove-box compartment and the electric fan
remote control base is not interrupted.
Check if the RED cable between the electric fan
remote control base and the electric fan motor is
not interrupted.
Check that the electric fan motor is earthed.
INJEC - 214
Vespa GTS Super 300 ie (2008)