Gilera 633721 Workshop Manual page 205

Nexus 500 euro 3
9 - Control unit with proper continuous power sup-
ply.
10 - If only one component is not powered check
the relevant connector. If the problem involves
both the decoder and CPU check the continuity of
the decoder CPU power supply line.
Pin 26 electronic control unit - Pin 87 engine stop
remote control switch = continuity
Pin 8 decoder - Pin 87 engine stop remote control
switch = continuity
YES go to 12 NO go to 11
11 - Fix the wiring or the connection
YES go to 10
12 - Proper continuous power supply
YES go to 13
13 - Check the connector and the continuity of the key switch set to "ON"
Pin B - F = Continuity
YES go to 14
14 - Check the engine stop remote control switch connector and the switch efficiency.
The connector can be recognised by its larger section white lead.
85 - 86 = approx. 70W
YES go to 15
N.B.
CHECK THE COIL RESISTANCE
15 - Check the signal circuit:
- emergency switch and connector
- side stand switch and connector
YES go to 16
16 - Check the cable harness continuity. Check the utility control main remote control switch.
Disconnect the master remote control switch.
Check the diode installed on the earth connection of the main remote control switch pickup.
86 - earth = continuity with high resistance (connect the tester: positive with 86; negative with earth).
When the polarity is inverted there should be no continuity.
Injection
INJEC - 205