Yamaha 2004 YP400, Service Manual, Page: 317 / 417

7 - 16
FI
FUEL INJECTION SYSTEM
Fault code No. 16 Symptom Stuck throttle position sensor detected.
Used diagnostic code No. 01 (throttle position sensor)
Order Inspection operation item and
probable cause Operation item and countermeasure Reinstatement
method
1 Installed condition of throttle posi-
tion sensor. Check the installed area for looseness or pinching.
Check that it is installed in the specified position.
Refer to “THROTTLE BODY AND FUEL INJEC-
TOR”. Reinstated by
starting the engine,
operating it at idle,
and then racing it.
2 Defective throttle position sensor Execute the diagnostic mode (code No. 01)
Replace if defective.
Refer to “THROTTLE BODY AND FUEL INJEC-
TOR”.
3 When fault code No. 15 has been
detected. Refer to “Fault code No. 15”. Refer to “Fault
code No. 15”.
Fault code No. 19 Symptom Open circuit in the input line of ECU (blue/yellow lead) detected.
Used diagnostic code No. 20 (sidestand switch)
Order Inspection operation item and
probable cause Operation item and countermeasure Reinstatement
method
1 Connected state of connector
Main wiring harness ECU coupler
(blue/yellow connector) Execute the diagnostic mode (code No. 20)
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 it
securely. Reinstated by
reconnecting the
wiring and retract-
ing the sidestand.
2 Open or short circuit in wiring har-
ness and/or sub lead. Repair or replace if there is an open circuit.
Sidestand switch signal input line of ECU coupler
blue/yellow
Fault code No. 21 Symptom Coolant temperature sensor open or short circuit is detected.
Used diagnostic code No. 06 (coolant temperature sensor)
Order Inspection operation item and
probable cause Operation item and countermeasure Reinstatement
method
1 Installed condition of sensor Check the installed area for looseness or pinching. Reinstated by turn-
ing the main switch
ON.
2 Connected condition of connector
Inspect 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 it
securely.
Coolant temperature sensor coupler
Main wiring harness ECU coupler
Sub-wire harness coupler
3 Open or short circuit in wiring har-
ness and/or sub lead. Repair or replace if there is an open or short circuit.
Between sensor coupler and ECU coupler
black/blue – black/blue
green/red – green/red
4 Defective coolant temperature sen-
sor. Execute the diagnostic mode (code No. 06)
Replace if defective.
Refer to “COOLING SYSTEM” in chapter 8.