PIAGGIO 633823 Service Station Manual page 198

Injection
Check the presence of fixed voltage between the
grey/black cable of the remote control base and
earth. If there is none check the continuity of the
grey/black cable between the fuse box (No. 4 10
A) and the remote control base.
N.B.
CONTINUITY TESTS MUST BE CARRIED OUT
WITH THE COMPONENTS DISCONNECTED.
(REMOTE CONTROLS, CONTROL UNIT,
FUSES ETC.).
INJEC - 46
MP3 250 i.e.