Yamaha XT660R S Service Manual page 364

Fault code No. 43
Used diagnostic code No. 09, 50 (fuel system voltage)
Order Item/components
1 Coupler connections
Fuel injection system relay cou-
pler
Wiring harness ECU coupler
2 Defective main relay
3 Open or short circuit in the wire har-
ness
4 Malfunction or open circuit in the
fuel injection system relay
FUEL INJECTION SYSTEM
Symptom The ECU is unable to monitor the battery voltage.
Check or maintenance job
Check the couplers for any pins that may have
pulled out.
Check that the couplers are securely locked.
If necessary, repair the coupler or securely con-
nect it.
Replace the relay if it is defective.
Execute the diagnostic mode. (Code No. 09)
Repair or replace if there is an open or short cir-
cuit:
between battery and fuel injection system fuse
Red - Red
between fuel injection system fuse and fuel injec-
tion system relay
Brown - Brown
between fuel injection system relay and ECU
Red/Blue - Red/Blue
between battery and main switch
Red - Red
between main switch and ignition fuse
Brown/Blue - Brown/Blue
between ignition fuse and engine stop switch
Red - Red
between engine stop switch and fuel injection
system relay
Red/Black - Red/Black
between fuel injection system relay and ECU
Blue/Red - Blue/Red
Execute the diagnostic mode. (Code No. 50)
Replace if defective.
1. Remove the relay unit.
2. Connect the pocket tester (Ω × 1) and battery
(12 V) to the relay terminals as shown.
Positive battery terminal → red/black 1
Negative battery terminal → blue/red 2
Positive tester probe → brown 3
Negative tester probe → red/blue 4
3. Does the diode have continuity between
brown and red/blue?
If there is no malfunction with the fuel injection
system relay, replace the ECU.
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FI
Restore method
Reinstated by start-
ing the engine and
operating it at idle.