DTC P0128 COOLANT THERMOSTAT (COOLANT TEMPERATURE BELOW THERMOSTAT REGULATING TEMPERATURE)
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DTC P0128 COOLANT THERMOSTAT (COOLANT TEMPERATURE
BELOW THERMOSTAT REGULATING TEMPERATURE)
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Detect the malfunction of thermostat function.
Judge NG when the engine coolant temperature is lower than the estimated
engine coolant temperature and the difference between them is large.
Judge OK when the engine coolant temperature becomes 70°C
(158°F) and the difference is small before judging NG.
(1)
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Valve
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(4)
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Piston
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(7)
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Stop ring
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(2)
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Spring
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(5)
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Guide
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(8)
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Wax element
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(3)
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Stopper
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(6)
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Rubber
packing
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(9)
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Jiggle
valve
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Secondary
Parameters
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Enable
Conditions
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None
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Always perform the diagnosis continuously.
Abnormality Judgment
Judge NG when the continuous time of completing
the malfunction criteria below becomes more than 30 seconds.
Judgment
Value
Malfunction
Criteria
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Threshold
Value
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Battery
voltage
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≥ 10.9
V
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Engine
coolant temperature at engine starting
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< 55°C
(131°F)
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Engine
coolant temperature
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< 70°C
(158°F)
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(Estimated − measured)
coolant temperature
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> 30°C
(86°F)
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Vehicle
speed
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≥ 30
km/h (19 MPH)
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Estimated
engine coolant temperature
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≥ 70°C
(158°F)
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Estimated
ambient temperature
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≥ −7°C
(19°F)
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Time Needed for Diagnosis:
Not
fixed.
Malfunction Indicator
Light Illumination:
Illuminates when malfunction occurs in
2 continuous driving cycles.
Normality Judgment
Judge OK and clear the NG when the malfunction
criteria below are completed.
Judgment
Value
Malfunction
Criteria
|
Threshold
Value
|
Battery
voltage
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≥ 10.9
V
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Engine
coolant temperature at engine starting
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< 55°C
(131°F)
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Engine
coolant temperature
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≥ 70°C
(158°F)
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(Estimated − measured)
coolant temperature
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≤ 30°C
(86°F)
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•
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When the OK idling cycle was completed 40 times
in a row
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•
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When “Clear Memory” was
performed
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MALFUNCTION
INDICATOR LIGHT CLEAR CONDITION
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•
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When the OK driving cycle was completed 3 times
in a row
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•
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When “Clear Memory” was
performed
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None
ECM OPERATING
AT DTC SETTING
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•
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Memorize the freeze frame data. (For test mode $02)
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•
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Memorize the diagnostic value and trouble
standard value. (For test mode $06)
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