Yamaha YZ 2019 Series Owner's Service Manual page 336

Fault code No. 43
Fault code No.
Item
Fail-safe system
Diagnostic code No.
Diagnostic tool display
Procedure
Probable cause of malfunc-
Item
tion and check
1 Connection of main relay cou-
pler.
Check the locking condition of
the coupler.
Disconnect the coupler and
check the pins (bent or broken
terminals and locking condition
of the pins).
2 Connection of wire harness
ECU coupler.
Check the locking condition of
the coupler.
Disconnect the coupler and
check the pins (bent or broken
terminals and locking condition
of the pins).
3 Wire harness continuity.
4 Defective main relay.
5 Defective main relay.
6 Malfunction in ECU.
43
Fuel system voltage: incorrect voltage supplied to the fuel injector
and fuel pump.
Able to start engine
Able to drive vehicle
09
Fuel system voltage
Approximately 12.0 (V)
Disconnect the main relay, and push the start switch.
Maintenance job
Improperly connected  Con-
nect the coupler securely or
repair/replace the wire harness.
Improperly connected  Con-
nect the coupler securely or
repair/replace the wire harness.
Open or short circuit  Replace
the wire harness.
Between battery terminal and
ECU coupler.
red–red
red–red/white
Between main relay coupler and
ECU coupler.
brown–brown
blue/red–blue/red
No operating sound  Replace
the main relay.
Execute the diagnostic mode.
(Code No. 09)
Fuel system voltage is below 3
V  Replace the main relay.
Replace the ECU.
8-37
FUEL INJECTION SYSTEM
Confirmation of service com-
pletion
Start the engine and let it idle for
approximately 5 seconds.
Fault code number is not dis-
played  Service is finished.
Fault code number is displayed
 Go to item 2.
Start the engine and let it idle for
approximately 5 seconds.
Fault code number is not dis-
played  Service is finished.
Fault code number is displayed
 Go to item 3.
Start the engine and let it idle for
approximately 5 seconds.
Fault code number is not dis-
played  Service is finished.
Fault code number is displayed
 Go to item 4.
Start the engine and let it idle for
approximately 5 seconds.
Fault code number is not dis-
played  Service is finished.
Fault code number is displayed
 Go to item 5.
Start the engine and let it idle for
approximately 5 seconds.
Fault code number is not dis-
played  Service is finished.
Fault code number is displayed
 Go to item 6.