Yamaha TMAX 2020 Service Manual page 524

SELF-DIAGNOSTIC FUNCTION AND DIAGNOSTIC CODE TABLE
DTC Item
P0638 YCC-T drive sys-
tem: malfunction de-
tected.
P0657 Fuel system volt-
age: incorrect volt-
age supplied to the
injector and fuel
pump.
P1601 Sidestand switch:
open or short circuit
of the light green
lead of the ECU is
detected.
Probable cause of
malfunction
• Defective coupler
between throttle
servo motor and
ECU.
• Open or short cir-
cuit in wire har-
ness between
throttle servo mo-
tor and ECU.
• Defective throttle
servo motor.
• Throttle servo mo-
tor is stuck (mech-
anism or motor).
• Malfunction in
ECU.
• Blown electric
throttle valve fuse.
• Open or short cir-
cuit in wire har-
ness between fuel
injection system
relay and ECU.
• Open circuit in wire
harness between
battery and ECU.
• Defective fuel in-
jection system re-
lay.
• Malfunction in
ECU.
• Defective coupler
between sidestand
relay and ECU.
• Open or short cir-
cuit in wire har-
ness between
sidestand relay
and ECU.
• Defective coupler
between sidestand
switch and side-
stand relay.
• Open or short cir-
cuit in wire har-
ness between
sidestand switch
and sidestand re-
lay.
• Defective side-
stand switch.
• Malfunction in
ECU.
9-50
Vehicle symptom
Engine response is
poor.
Loss of engine pow-
er.
Engine idling speed
is unstable.
Engine is difficult to
start.
Increased exhaust
emissions.
Engine cannot be
started.
Fail-safe system
operation
feedback is not
O
2
carried out.
YCC-T evacuation
is activated.
Output is restricted.
ISC feedback is not
carried out.
ISC learning is not
carried out.
Cruise control sys-
tem cannot be oper-
ated.
Monitor voltage = 12
[V]
O feedback is not
2
carried out.
Cruise control sys-
tem cannot be oper-
ated.
Engine is forcefully
stopped (the injector
output is stopped).
Cruise control sys-
tem cannot be oper-
ated.