Yamaha 2004 YP400, Service Manual, Page: 316 / 417

7 - 15
FI
FUEL INJECTION SYSTEM
Fault code No. 14 Symptom Intake air pressure sensor - hose system malfunction (clogged or detached
hose).
Used diagnostic code No. 03 (intake air pressure sensor)
Order Inspection operation item and
probable cause Operation item and countermeasure Reinstatement
method
1 Intake air pressure sensor hose
detached, clogged, kinked, or
pinched.
Intake air pressure sensor mal-
function at intermediate electrical
potential. Repair or replace the sensor hose.
Inspect and repair the connection. Reinstated by
starting the engine
and operating it at
idle.
2 Connected state of connector
Intake air pressure sensor coupler
Main wiring harness ECU coupler Check the coupler for any pins that may have pulled
out.
Check that the coupler is connected securely.
If there is a malfunction, repair it and connect it
securely.
3 Defective intake air pressure sen-
sor. Execute the diagnostic mode (code No. 03)
Replace if defective.
Refer to “Fault code No. 13”.
Fault code No. 15 Symptom Throttle position sensor - open or short circuit 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 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.
Throttle position 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
yellow – yellow, yellow/blue – yellow/blue
blue – blue
4 Throttle position sensor lead wire
open circuit output voltage check. Check for open circuit and replace the throttle posi-
tion sensor.
black/blue – yellow/blue
5 Defective throttle position sensor. Execute the diagnostic mode (code No. 01)
Replace if defective.
Refer to “THROTTLE BODY AND FUEL INJEC-
TOR”.