Yamaha YP125R, Service Manual

Page: 433 / 498

FUEL INJECTION SYSTEM
8-36
• If a diagnostic code number does not have a corresponding fault code number, the information is
shown in “DIAGNOSTIC CODE TABLE”. (Refer to “DIAGNOSTIC CODE TABLE” on page 8-54.)
EAS27481
TROUBLESHOOTING DETAILS
This section describes the measures per fault code number displayed on the meter. Check and service
the items or components that are the probable cause of the malfunction following the order given.
After the check and service of the malfunctioning part have been completed, reset the meter display
according to the reinstatement method.
Fault code No.:
Fault code number displayed on the meter when the engine failed to work normally.
Diagnostic code No.:
Diagnostic code number to be used when the diagnostic mode is operated. Refer to “DIAGNOSTIC
MODE” on page 8-34.
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. —
FI diagnostic tool display —
Checking method —
Probable cause of malfunction Check or maintenance job
1 Installed condition of crankshaft position
sensor. • Check for looseness or pinching.
2 Connections
• Crankshaft position sensor coupler
• Wire harness ECU coupler • Check the coupler for any pins that may be
pulled out.
• Check the locking condition of the coupler.
• If there is a malfunction, repair it and connect
the coupler securely.
3 Open or short circuit in wire harness. • Repair or replace if there is an open or short
circuit.
• Between the crankshaft position sensor cou-
pler and ECU coupler.
(gray/black–gray/black)
(white/red–white/red)
4 Defective crankshaft position sensor. • Replace if defective.
Refer to “CHECKING THE CRANKSHAFT
POSITION SENSOR” on page 8-83.
Reinstatement method Cranking the engine.