Yamaha MTN850-A 2017 Service Manual page 542

SELF-DIAGNOSTIC FUNCTION AND DIAGNOSTIC CODE TABLE
Fault
Item
code No.
P0601 Internal malfunction in
ECU (ROM data
error) (When this mal-
function is detected in
the ECU, the fault
code number might
not appear on the tool
display.)
P0606 Internal malfunction in
ECU (processor error)
(When this malfunc-
tion is detected in the
ECU, the fault code
number might not
appear on the tool
display.)
P062F EEPROM fault code
number (an error is
detected while read-
ing or writing on
EEPROM)
P0638 YCC-T drive system:
malfunction detected.
P0657 Fuel system voltage
(incorrect voltage sup-
plied to the fuel injec-
tor, fuel pump and
relay unit)
Probable cause of
malfunction
• Malfunction in ECU.
• Malfunction in ECU.
• CO adjustment
value is not properly
written.
• ISC learning value is
not properly written.
• OBD memory value
is not properly writ-
ten.
• Malfunction in ECU.
• Defective coupler
between throttle
servo motor and
ECU.
• Open or short cir-
cuit in wire harness
between throttle
servo motor and
ECU.
• Defective throttle
servo motor.
• Throttle servo motor
is stuck (mecha-
nism or motor).
• Malfunction in ECU.
• Blown electronic
throttle valve fuse.
• Open or short cir-
cuit in wire harness
between relay unit
and ECU.
• Open circuit in wire
harness between
battery and ECU.
• Defective relay unit.
• Malfunction in ECU.
9-9
Vehicle symptom
Engine cannot be
started.
Engine cannot be
started.
Engine response is
poor.
Loss of engine power.
Increased exhaust
emissions.
Engine cannot be
started or is difficult to
start.
Engine idling speed is
unstable.
OBD memory value is
not correct.
Engine response is
poor.
Loss of engine power.
Engine idling speed is
unstable.
Engine is difficult to
start.
Increased exhaust
emissions.
Fail-safe system
operation
Engine cannot be
started.
Engine cannot be
started.
Ignition and injection
are not carried out.
Judgment for other
fault codes is not car-
ried out.
Load control is not
carried out. (The relay
unit, headlight relay,
and other relays are
all turned off.)
The CO adjustment
mode and diagnostic
mode cannot be acti-
vated.
Output is restricted.
CO adjustment value
for the faulty cylinder
= 0 (default value)
ISC learning values =
Default values
OBD memory value is
initialized.
Initialization of O
2
feedback learning
value.
O feedback is not
2
carried out.
YCC-T evacuation is
activated.
Output is restricted.
ISC feedback is not
carried out.
ISC learning is not
carried out.
Monitor voltage = 12
[V]
O feedback is not
2
carried out.