Yamaha YZ 2019 Series, Owner'S Service Manual

Page: 324 / 398

FUEL INJECTION SYSTEM
8-25
EAM30286
TROUBLESHOOTING DETAILS
This section describes the measures per fault code number displayed on the diagnostic tool. Check and
service the items or components that are the probable cause of the malfunction following the order giv-
en.
After the check and service of the malfunctioning part have been completed, reset the diagnostic tool
display according to the reinstatement method.
Fault code No.:
Fault code number displayed on the diagnostic tool when the engine failed to work normally.
Diagnostic code No.:
Diagnostic code number to be used when the diagnostic mode is operated.
Fault code No. 12
Fault code No. 12
Item
Crankshaft position sensor: no normal signals are received from
the crankshaft position sensor.
Fail-safe system
Unable to start engine
Unable to drive vehicle
Diagnostic code No.
—
Diagnostic tool display
—
Procedure
—
Item
Probable cause of malfunc-
tion and check
Maintenance job
Confirmation of service com-
pletion
1 Connection of crankshaft posi-
tion sensor 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).
Improperly connected

Con-
nect the coupler securely or
repair/replace the wire harness.
Crank the engine.
Fault code number is not dis-
played

Service is finished.
Fault code number is displayed

Go to item 2.
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).
Improperly connected

Con-
nect the coupler securely or
repair/replace the wire harness.
Crank the engine.
Fault code number is not dis-
played

Service is finished.
Fault code number is displayed

Go to item 3.
3 Wire harness continuity. Open or short circuit

Replace
the wire harness.
Between the crankshaft position
sensor coupler and ECU cou-
pler.
black/blue–black/blue
gray–gray
Crank the engine.
Fault code number is not dis-
played

Service is finished.
Fault code number is displayed

Go to item 4.
4 Installed condition of crankshaft
position sensor.
Check for looseness or pinch-
ing.
Check the gap between the
crankshaft position sensor and
the pickup rotor.
Improperly installed sensor

Reinstall or replace the sensor.
Refer to “GENERATOR AND
STARTER CLUTCH” on page
5-58.
Crank the engine.
Fault code number is not dis-
played

Service is finished.
Fault code number is displayed

Go to item 5.