Gilera Nexus 500 Workshop Manual page 291

Nexus 500
YES go to 16 NO go to 15
15 - Check cable harness and connectors more carefully.
16 - Connect the control unit connector.
Set the switch to «ON» with switch to «RUN» and side stand raised. Repeat the "ON" "OFF" "ON"
switching.
Check the presence of voltage pulses on the stepper command lines.
Set-up for direct voltage measurements.
N.B.
PULSES ARE USED TO CHANGE THE STEPPER POSITION.
Electric characteristic
14-24 =
V (pulses for a few seconds)
6-21 =
V (pulses for a few seconds)
After reaching the optimum position, the power
supply voltage becomes null.
YES go to 17 NO go to 18
17 - The stepper circuit is efficient.
18 - Check the control unit connector. Replace the control unit, if necessary.
Injection
INJEC - 99