Suzuki GSF1250 Service Manual page 557

Step
3 1) Turn the ignition switch OFF.
2) Remove the left frame cover. Refer to "Exterior Parts
Removal and Installation in Section 9D (Page 9D-6)".
3) Remove the fuse box mounting bolt. Refer to "ABS
Control Unit Coupler Disconnect and Connect (Page 4E-
70)".
4) Check the ABS control unit coupler for loose or poor
contacts. If OK, then disconnect the ABS control unit
coupler.
5) Start the engine at 5 000 r/min with the dimmer switch
set to HI.
6) Measure the voltage between "16" (O/Y) and "24" (B/W)
at the coupler.
Special tool
(A): 09900–25008 (Multi-circuit tester set)
Tester knob indication
Voltage ( )
18
10
3
2
Is the voltage same as Step 2?
Action
( )
21
24 25
16
12 13
8 9
4
(A)
( )
Yes
Replace the ABS
control unit/HU.
(A)
I718H1450036-04
ABS: 4E-64
No
Inspect the wire
harness. (Faulty ignition
or ground wire)