Yamaha MBK MW125 2014, Service Manual

Page: 339 / 380

FUEL INJECTION SYSTEM
8-42
A-1 Incorrect speed sensor signal. Check the speed sensor.
Execute the diagnostic mode.
(Code No. 07)
Front wheel stop: The pulse in-
tegrated value should be con-
stant.
Rotate the front wheel a few
turns manually and enter the
speed pulse: The pulse inte-
grated value will be added.
Indication is incorrect.
→
Refer
to Fault code No. 42
Start and idle the engine for ap-
proximately 10 seconds.
Fault code number is not dis-
played
→
Service is finished.
Fault code number is displayed
→
Go to item A-2.
A-2 Throttle valve is not fully open
due to the defective throttle ca-
ble. Check the throttle cable.
Refer to “CHECKING THE
THROTTLE GRIP OPERA-
TION” on page 3-24. Start and idle the engine for ap-
proximately 10 seconds.
Fault code number is not dis-
played
→
Service is finished.
Fault code number is displayed
→
Go to item A-3.
A-3 Air leak from the throttle body. Check the throttle body.
Refer to “CHECKING THE
THROTTLE BODY” on page
7-9. Start and idle the engine for ap-
proximately 10 seconds.
Fault code number is not dis-
played
→
Service is finished.
Fault code number is displayed
→
Go to item A-4.
A-4 Air leak from the ISC system. Check the ISC valve as follows.
Check the mounting area for
looseness or pinching.
Make sure that the installation
position is correct.
Check the intake air passages
for air leaks. Start and idle the engine for ap-
proximately 10 seconds.
Fault code number is not dis-
played
→
Service is finished.
Fault code number is displayed
→
Go to item A-5.
A-5 The air volume for the throttle
valve and ISC valve is exces-
sive. Clean the throttle valve and ISC
valve.
Refer to “CLEANING THE ISC
(IDLE SPEED CONTROL)
UNIT AND THROTTLE BODY”
on page 7-9. Start and idle the engine for ap-
proximately 10 seconds.
Fault code number is not dis-
played
→
Service is finished.
Fault code number is displayed
→
Go to item A-6.
A-6 Faulty ISC valve operation. Replace the ISC valve.
Refer to “CLEANING THE ISC
(IDLE SPEED CONTROL)
UNIT AND THROTTLE BODY”
on page 7-9. Start and idle the engine for ap-
proximately 10 seconds.
Fault code number is not dis-
played
→
Service is finished.
Fault code number is displayed
→
Go to item A-7.
A-7 Malfunction in ECU. Replace the ECU.
Refer to “REPLACING THE
ECU (engine control unit)” on
page 8-59. Execute the diagnostic mode.
(Code No. 54)
Return the ISC valve to the ini-
tial opening position.
B-1 Connection of ISC 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 re-
place the wire harness.
Execute the diagnostic mode.
(Code No. 54)
ISC valve operation sound is
heard.
→
Go to item B-8.
ISC valve operation sound is
not heard.
→
Go to item B-2.
Fault code No. 37
Item Engine speed is high when the engine is idling.