Suzuki GRAND VITARA Owner's Manual page 1658

10B-22 Body Electrical Control System:
Step
3 Check DTC in BCM
1) Turn ignition switch to OFF position.
2) Connect connectors of disconnected control modules
communicating by means of CAN.
3) Disconnect connector from any one of control modules
other than BCM.
4) Recheck DTC for BCM.
Is DTC U1073 detected?
Action Yes
Disconnect connectors
of control modules other
than the one whose
connector is
disconnected in Step 3)
one by one and check
that DTC U1073 is
detected by BCM each
time connector is
disconnected. When
DTC U1073 is not
detected by BCM while
checking in this way, go
to description under
"NO" below. If DTC
U1073 is detected by
BCM even when
connectors of all control
modules that use CAN
communication with
BCM are disconnected,
substitute a known-
good BCM and recheck.
No
Check power and
ground circuit of control
module disconnect in
Step 3). If circuit is OK,
substitute a known-
good control module
disconnected in Step 3)
and recheck.