PIAGGIO 500 cc Service Manual page 204

Fuel injection
Disconnect the stepper connection.
Check the resistance of the stepper circuits
connecting the tester as shown in the diagram.
The two measurements must have the same value.
Resistance = ~ 51 Ω
YES
Connect the special tool 020481Y. See page 9-8
For these controls do not connect the special
tool to the control unit.
Check continuity of the 4 feed wires
of the stepper.
A Light blue-red-14 = 0 Ω (continuity)
B Orange-blue-6 = 0 Ω (continuity)
C Light blue-yellow-21 = 0 Ω (continuity)
D Light blue-black-24 = 0 Ω (continuity)
Check the earthing isolation of the 4
wires of the stepper.
14-23 = >1MΩ (infinity)
6-23 = >1MΩ (infinity)
21-23 = >1MΩ (infinity)
24-23 = >1MΩ (infinity)
9 - 92
Proceed with control of the stepper circuit.
Proceed with replacement of the throttle body.
See Chapter. 7-THERMAL UNIT AND TIMING SYSTEM.
YES
NO
YES
NO
YES
NO