2012 YAMAHA YZ450F display

7-32
FUEL INJECTION SYSTEM
4 Defective AC magneto. Defective → Replace.
Refer to "CHECKING THE AC
MAGNETO" section.Start the engine, set the
switch on the FI diagnostic
tool sub-wire harness to
"OFF" while the engine is
idling, and let the engine
continue to idle for 5 sec-
onds or more.
After completing the above
operation, check whether a
fault code number is dis-
played.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 5.
5 Malfunction in ECU. Replace the ECU.
Fault code No. 50
Symptom ECU internal malfunction
Fail-safe system Unable to start
Unable to drive
Diagnostic code No. —
FI diagnostic tool display —
Checking method —
Item Item/components and probable cause Check or maintenance job Checking method
1 Malfunction in ECU. Replace the ECU. Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is fin-
ished. Fault code No. 46
Symptom Power supply to the ECU is not normal.
Fail-safe system Able to start (depending on circumstances)
Able to drive vehicle (depending on circumstances)
Diagnostic code No. —
FI diagnostic tool display —
Checking method —
Item Item/components and probable cause Check or maintenance job Checking method

7-33
FUEL INJECTION SYSTEM
Fault code No. waiting for connection
Symptom Communication signal is not received.
Fail-safe system Able to start (unable when ECU is malfunctioning)
Able to drive vehicle (unable when ECU is malfunctioning)
Diagnostic code No. —
FI diagnostic tool display —
Checking method —
Item Item/components and probable cause Check or maintenance job Checking method
1 Check the connection and locking condition of
the FI diagnostic tool coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection → Properly con-
nect, repair, or replace.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 2.
2 Check the connection and locking condition of
the wire harness ECU coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection → Properly con-
nect, repair, or replace.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 3.
3 Continuity of harness Open or short circuit → Replace.
Between FI diagnostic tool coupler
and ECU coupler.
(Light green–Light green)Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 4.
4 FI diagnostic tool malfunction Replace the FI diagnostic tool. Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 5.
5 Malfunction in ECU. Replace the ECU.

7-34
FUEL INJECTION SYSTEM
Fault code No. Er-4
Symptom Registered data cannot be received from the FI diagnostic tool.
Fail-safe system Able to start
Able to drive
Diagnostic code No. —
FI diagnostic tool display —
Checking method —
Item Item/components and probable cause Check or maintenance job Checking method
1 Check the connection and locking condition of
the FI diagnostic tool coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection → Properly con-
nect, repair, or replace.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 2.
2 Check the connection and locking condition of
the wire harness ECU coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection → Properly con-
nect, repair, or replace.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 3.
3 Continuity of harness Open or short circuit → Replace.
Between FI diagnostic tool coupler
and ECU coupler.
(Light green–Light green)Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 4.
4 FI diagnostic tool malfunction Replace the FI diagnostic tool. Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 5.
5 Malfunction in ECU. Replace the ECU.