Gilera 633721 Workshop Manual page 282

Injection
YES go to 12 NO go to 13
12 - Check the earth insulation of the 4 Stepper lines.
Electric characteristic
14-23 =
>1 MΩ (infinite)
6-23 =
>1 MΩ (infinite)
21-23 =
>1 MΩ (infinite)
24-23 =
>1 MΩ (infinite)
YES go to 14 NO go to 13
13 - Repair or replace the wiring.
YES go to 11
14 - Connect the Stepper connector.
Repeat the continuity check with the tool pins.
Electric characteristic
14-24 =
approx. 51 Ω
6-21 =
approx. 51 Ω
INJEC - 282
Nexus 500 euro 3