PIAGGIO 500 cc Service Manual page 214

Fuel injection
Keeping the electromagnetic switch
disconnected, check continuity between 86 of
the electromagnetic switch connector and 5
of the control unit.
86 (Green-White) - 5 = 0 Ω (continuity)
YES
Disconnect the connector between
the vehicle system and fuel injection
Check the connector and repeat
continuity controls.
86 - Green-White = 0 Ω (continuity)
Green-White - 5 = 0 Ω (continuity)
Check the earthing isolation.
5 - 23 > 1MΩ (infinity).
YES
9 - 102
system.
Repair or replace the harness.
NO
NO