Yamaha 2004 YP400, Service Manual, Page: 322 / 417

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FI
FUEL INJECTION SYSTEM
Fault code No. 43 Symptom Supply power to the fuel injector and fuel pump is not normal.
Used diagnostic code No. 09 (fuel system voltage)
Order Inspection operation item and
probable cause Operation item and countermeasure Reinstatement
method
1 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.
Fuel injection system relay coupler
Fuel pump coupler
Fuel injector coupler
ECU coupler
Reinstated by
starting the engine
and operating it at
idle.
2 Malfunction in ECU Fuel injection system relay is on.
3 Open or short circuit in the wiring
harness. Repair or replace if there is an open or short circuit.
Between battery and ECU coupler
red – red
red/blue – red/blue
4 Malfunction or open circuit in fuel
injection system relay Execute the diagnostic mode (code No. 09)
NOTE:
When the leads are disconnected, the voltage check
by the code No. 09 is impossible.
Replace if defective.
1. Remove the fuel injection system relay.
2. Connect the pocket tester (
Ω ×
1) and battery
(12 V) to the starting circuit cut-off relay terminals
as shown.
3. Does the fuel injection system relay have conti-
nuity between red and red/blue?
Positive battery terminal
→
red/black
1
Negative battery terminal
→
red/yellow
2
Positive tester probe
→
red
3
Negative tester probe
→
red/blue
4
R
R / L
R / B R / Y
3
4
2
1