Yamaha YZ 2018 Series, Owner'S Service Manual

Page: 329 / 402

FUEL INJECTION SYSTEM
8-30
TIP
• If fault code numbers 13 and 14 are both displayed, perform the checks and maintenance jobs for
fault code number 13 first.
• Before troubleshooting, disconnect the starter motor lead from the starter relay.
5 Defective crankshaft position
sensor. Check the crankshaft position
sensor.
Refer to “CHECKING THE
CRANKSHAFT POSITION
SENSOR” on page 8-67. Crank the engine.
Fault code number is not dis-
played

Service is finished.
Fault code number is dis-
played

Go to item 6.
6 Malfunction in ECU. Replace the ECU.
Fault code No. 13
Item Intake air pressure sensor: open or short circuit detected.
Fail-safe system Able to start engine
Able to drive vehicle
Diagnostic code No. 03
Diagnostic tool display Displays the intake air pressure.
Procedure Operate the throttle while pushing the start switch.(If the display
value changes, the performance is OK.)
Item
Probable cause of malfunc-
tion and check
Maintenance job
Confirmation of service
completion
1 Connection of intake air pres-
sure sensor coupler.
Check the locking condition
of the coupler.
Disconnect the coupler and
check the pins (bent or bro-
ken terminals and locking
condition of the pins). Improperly connected

Connect the coupler securely
or repair/replace the wire har-
ness.
Push the start switch.
Fault code number is not dis-
played

Service is finished.
Fault code number is dis-
played

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 bro-
ken terminals and locking
condition of the pins). Improperly connected

Connect the coupler securely
or repair/replace the wire har-
ness.
Push the start switch.
Fault code number is not dis-
played

Service is finished.
Fault code number is dis-
played

Go to item 3.
3 Wire harness continuity. Open or short circuit

Re-
place the wire harness.
Between intake air pressure
sensor coupler and ECU cou-
pler.
black/blue–black/blue
pink–pink
blue–blue
Push the start switch.
Fault code number is not dis-
played

Service is finished.
Fault code number is dis-
played

Go to item 4.
Fault code No. 12
Item
Crankshaft position sensor: no normal signals are received
from the crankshaft position sensor.