P0125

DTC P0125 - INSUFFICIENT COOLANT TEMPERATURE FOR CLOSED LOOP FUEL CONTROL

OUTLINE OF DIAGNOSIS
Detect the malfunction of engine coolant temperature output property. Judge NG when the engine coolant temperature does not rise whereas it seemed to rise from the viewpoint of the engine condition.




COMPONENT DESCRIPTION




ENABLE CONDITION

GENERAL DRIVING CYCLE
Perform the diagnosis only once after engine starting.

DIAGNOSTIC METHOD




- Abnormality Judgment
Judge NG when the malfunction criteria are completed.

Timer for diagnosis after engine starting
a. Timer stop at fuel cut mode.
b. During the driving conditions except a) above, timer count up by 65.5 milliseconds + TWCNT milliseconds at every 65.5 milliseconds.
Where,TWCNT is determined as follows,

TWCNT = 0 at idle switch ON,




TWCNT show on the following table at idle switch OFF.

Judgment value of timer after engine starting t = 429.5 - 6.685 x Ti

Ti is the lowest coolant temperature after starting the engine.
Time Needed for Diagnosis: To be determined. (It is varied by the Min. engine coolant temperature and engine conditions such as vehicle speed and engine coolant temperature.)
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 are completed.

DTC CLEAR CONDITION
- When the OK idling cycle was completed 40 times in a row
- When "Clear Memory" was performed

MALFUNCTION INDICATOR LIGHT CLEAR CONDITION
- When the OK driving cycle was completed 3 times in a row
- When "Clear Memory" was performed

FAIL SAFE
- Engine coolant temperature process: Fix the engine coolant temperature at 70 °C (158 °F).
- ISC feedback: Calculate the target engine speed setting the engine coolant temperature to 70 °C (158 °F).
- ISC learning: Not allowed to learn.
- Heavy fuel judgment control: Not allowed to carry out the heavy judgment.
- Air conditioner control: Not allowed to turn the air conditioner to ON.
- Radiator fan control: Both main and sub fan are in High driving.
- Increase compensation coefficient at a high water temperature: The water temperature condition is disregarded and increased by approval of other condition, though usually increases by a high water temperature and approval of other condition.

ECM OPERATING AT DTC SETTING
Memorize the freeze frame data. (For test mode $02)