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System Description
NHEC0554
COOLING FAN CONTROL
NHEC0554S01
Sensor Input Signal to ECM
ECM func-
tion
Actuator
Vehicle speed sensor Vehicle speed
Cooling fan
control
Cooling fan relay(s)
Engine coolant temperature sensor Engine coolant temperature
Air conditioner switch Air conditioner “ON” signal
Ignition switch Start signal
The ECM controls the cooling fan corresponding to the vehicle speed, engine coolant temperature, refriger-
ant pressure and air conditioner ON signal. The control system has 3-step control [HIGH/LOW/OFF].
OPERATION
NHEC0554S02
SEF578XA
CONSULT-II Reference Value in Data Monitor
Mode
NHEC0555
Specification data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
AIR COND SIG
I Engine: After warming up, idle
the engine
Air conditioner switch: OFF OFF
Air conditioner switch: ON
(Compressor operates)
ON
COOLING FAN
I After warming up engine, idle
the engine.
I Air conditioner switch: OFF
Engine coolant temperature is
94°C (201°F) or less
OFF
Engine coolant temperature is
between 95°C (203°F) and 104°C
(219°F)
LOW
Engine coolant temperature is
105°C (221°F) or more
HIGH
GI
MA
EM
LC
FE
AT
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P1217 ENGINE OVER TEMPERATURE (OVERHEAT)
System Description
EC-489
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