The CODE control unit
M20 is supplied at pin 3 by
the battery from the line for the maxifuse EFI (UGD) of B5 and is protected by fuse B35.
The supply controlled by the ignition (15/54)
reaches pin 8 through the line protected bu fuse
B25.Pin 4 is earthed.
The line leading from pin 6 is a serial
line leading to engine management unit
M10, which is
responsible for identifying the key and exchanging codes.
It is possible to "read" the control
unit autodiagnostic system, by connecting to the autodiagnostic
connector
R10 from pin 5 of the control unit M20.
The autodiagnostic system also produces
the signal for the "CODE failure" warning light, located
in the instrument panel
E50: it involves an earth signal
coming out of pin 2 of the control unit M20.
The instrument panel
E50 is controlled
by the ignition (INT) at pin 2 of connector A from the line protected
by fuse F1 of the junction unit B1:
when an earth signal reaches pin 12 of connector C, the "CODE
warning" light comes on.A second control unit connector is connected
via two leads to the aerial, fitted coaxially to the ignition key,
in order to detect key insertion and rotation.