Yamaha YZ250F(E), Owner'S Service Manual

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FUEL INJECTION SYSTEM
8-31
Fault code Er-4
Symptom
Registered data cannot be received from the Yamaha diagnos-
tic tool.
Fail-safe system Able to start engine
Able to drive vehicle
Diagnostic code No. —
Diagnostic tool display —
Procedure —
Or-
der
Probable cause of malfunc-
tion and check
Maintenance job Reinstatement method
1 Connection of Yamaha diag-
nostic tool coupler.
Check the locking condition
of the coupler.
Disconnect the coupler, and
check the pins (for bent or
broken terminals and locking
condition of the pins).
Improperly connected

Connect the coupler secure-
ly, or repair/replace the wire
harness.
Turn “ON” the switch on the
FI diagnostic tool sub-lead.
Fault code No. is not dis-
played

Repair is finished.
Fault code No. is displayed

Go to next order.
2 Connection of wire harness
ECU coupler.
Check the locking condition
of the coupler.
Disconnect the coupler, and
check the pins (for bent or
broken terminals and locking
condition of the pins).
Improperly connected

Connect the coupler secure-
ly, or repair/replace the wire
harness.
Turn “ON” the switch on the
FI diagnostic tool sub-lead.
Fault code No. is not dis-
played

Repair is finished.
Fault code No. is displayed

Go to next order.
3 Wire harness continuity. Open or short circuit

Re-
place the wire harness.
light green–light green
Turn “ON” the switch on the
FI diagnostic tool sub-lead.
Fault code No. is not dis-
played

Repair is finished.
Fault code No. is displayed

Go to next order.
4 Yamaha diagnostic tool mal-
function
Replace the Yamaha diag-
nostic tool.
Turn “ON” the switch on the
FI diagnostic tool sub-lead.
Fault code No. is not dis-
played

Repair is finished.
Fault code No. is displayed

Go to next order.
5 Faulty ECU Replace the ECU.