Yamaha WR125R 2009, Service Manual

Page: 327 / 372

FUEL INJECTION SYSTEM
8-42
EAS27471
TROUBLESHOOTING DETAILS
This section describes the measures per fault code number displayed on the FI diagnostic tool. 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 FI diagnostic tool
display according to the reinstatement method.
Fault code No.:
Fault code number displayed on the FI diagnostic tool when the engine failed to work normally. Refer
to “Diagnostic code table”.
Diagnostic code No.:
Diagnostic code number to be used when the diagnostic mode is operated. Refer to “Sensor operation
table” and “Actuator operation table”.
ERROR_4
Commands from the FI di-
agnostic tool are not ac-
cepted by the ECU.
• Set the main switch to “OFF” once, and then
set the FI diagnostic tool to the CO adjustment
mode or the diagnostic mode.
• Vehicle battery is insufficiently charged.
• Malfunction in wire harness ECU coupler.
• Malfunction in FI diagnostic tool coupler.
• Open or short circuit in wire harness.
• Malfunction in the FI diagnostic tool.
• Malfunction in the ECU.
Fault code No. 12 Symptom No normal signals are received from the crankshaft posi-
tion sensor.
Diagnostic code No. — —
Order Item/components and probable
cause
Check or maintenance job Reinstatement
method
1 Installed condition of crankshaft posi-
tion sensor. Check for looseness or pinching. Crank the en-
gine.
2 Connections
• Crankshaft position sensor coupler
• Wire harness ECU coupler • Check the coupler for any pins
that may have pulled out.
• Check the locking condition of
the coupler.
• If there is a malfunction, repair it
and connect the coupler se-
curely.
3 Open or short circuit in wire harness. • Repair or replace if there is an
open or short circuit.
• Between the crankshaft position
sensor coupler and ECU cou-
pler.
(red–red)
(gray/black–gray/black)
4 Defective crankshaft position sensor. • Replace if defective.
Refer to “CHECKING THE
CRANKSHAFT POSITION
SENSOR” on page 8-71.
LCD Display Symptom Probable cause of malfunction