Suzuki GSX-R750 Service Manual page 249

Step 1 (When indicating P1657-L:)
1) Turn the ignition switch OFF.
2) Remove the frame cover. (5-8)
3) Check the EXCVA position sensor coupler for loose or poor
contacts.
If OK, then check the EXCVA position sensor lead wire conti-
nuity.
4) Disconnect the EXCVA position sensor coupler.
5) Check the continuity between Y wire A and ground.
6) Also, check the continuity between Y wire A and B/Br wire
B. If the sound is not heard from the tester, the circuit condi-
tion is OK.
7) Disconnect the ECM coupler.
8) Check the continuity between Y wire A and terminal 5.
9) Also, check the continuity between R wire C and terminal A.
 EXCVA lead wire continuity: Continuity ()
 09900-25008: Multi-circuit tester set
09900-25009: Needle pointed probe set
 Tester knob indication: Continuity test ()

When using the multi-circuit tester, do not storongly
touch the terminal of the ECM coupler with a needle
pointed tester probe to prevent the terminal damage
or terminal bend.
Is the continuity OK?
YES Go to Step 2 and Go to Step 4.
NO R or Y wire open, or Y wire shorted to ground
10)After repairing the trouble, clear the DTC using SDS tool.
(4-27)
FI SYSTEM DIAGNOSIS
1
1
!
1
(Black)
ECM couplers (Harness side)
4-93
!
(Gray)