Yamaha 2004 YP400, Service Manual, Page: 324 / 417

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FI
FUEL INJECTION SYSTEM
Fault code No. 50 Symptom Faulty ECU memory. (When this malfunction is detected in the ECU, the fault
code number might not appear on the meter.)
Used diagnostic code No. – –
Order Inspection operation item and
probable cause Operation item and countermeasure Reinstatement
method
1 Malfunction in ECU Replace the ECU. Reinstated by turn-
ing the main switch
ON.
Fault code No. 61 Symptom ISC (idle speed control) valve open or short circuit is detected.
Used diagnostic code No. – –
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.
ISC (idle speed control) valve coupler
Main wiring harness ECU coupler
Sub-wire harness coupler
Reinstated by set-
ting the main
switch to ON. The
ISC (idle speed
control) valve fully
closes, and then it
opens until it is at
the standby open-
ing position when
the engine is
started.
2 Open or short circuit in lead. Repair or replace if there is an open or short circuit.
Between ISC (idle speed control) valve and ECU
coupler/main harness
pink – pink
light green – light green
gray – gray
sky blue – sky blue
3 Detective ISC (idle speed control)
valve Execute diagnostic mode (code No. 54)
Replace if defective.
Refer to “THROTTLE BODY AND FUEL INJEC-
TOR”.
Fault code No. Er-1 Symptom No signals are received from the ECU.
Used diagnostic code No. – –
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.
Main wiring harness ECU coupler
Sub-wire harness coupler
Reinstated if nor-
mal signal is
received from the
ECU when the
main switch is set
to ON.
2 Open or short circuit in wiring har-
ness and/or sub lead. Repair or replace if there is an open or short circuit.
Between meter coupler and ECU coupler
yellow/blue – yellow/blue
3 Malfunction in meter Replace the meter.
4 Malfunction in ECU Replace the ECU.