Yamaha YP125R, Service Manual

Page: 444 / 498

FUEL INJECTION SYSTEM
8-47
Fault code No. 42
Item
Speed sensor: no normal signals are received from the speed
sensor.
Fail-safe system
Able to start engine
Able to drive vehicle
Diagnostic code No. 07
FI diagnostic tool display 0–999
Checking method
Check that the number increases when the front wheel is rotated.
The number is cumulative and does not reset each time the wheel
is stopped.
Probable cause of malfunction Check or maintenance job
1 Connections
• Speed 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.
2 Open or short circuit in wire harness. • Repair or replace if there is an open or short
circuit.
• Between speed sensor coupler and ECU cou-
pler.
(gray/red–gray/red)
(gray–gray)
(gray/black–gray/black)
3 Defective speed sensor. • Execute the diagnostic mode. (Code No. 07)
• Replace if defective.
Refer to “CHECKING THE SPEED SENSOR”
on page 8-87.
4 This fault code will appear on the multi-
function display if the vehicle speed is
less than 2 km/h, the throttle is opened
70 degrees or more, and the engine
speed exceeds 7000 r/min with the vehi-
cle on the centerstand. This, therefore,
does not indicate a malfunction. —
Reinstatement method
Starting the engine, and inputting the vehicle speed signals by op-
erating the vehicle at a 20 to 30 km/h.
Fault code No. 43
Item
Fuel system voltage: the ECU is unable to monitor the battery
voltage (an open or short circuit in the line to the ECU).
Fail-safe system
Able to start engine
Able to drive vehicle
Diagnostic code No. 09
FI diagnostic tool display Approximately 12.0