DTC P1491 POSITIVE CRANKCASE VENTILATION (BLOW-BY) FUNCTION PROBLEM

DTC P1491 POSITIVE CRANKCASE VENTILATION (BLOW-BY) FUNCTION PROBLEM

(1)	Engine control module (ECM)
(2)	Detecting circuit
(3)	PCV diagnosis connector
(4)	5 V

ENABLE CONDITION

Secondary Parameter	Enable Condition
None

GENERAL DRIVING CYCLE

Always perform the diagnosis continuously.

DIAGNOSIS METHOD

Abnormality Judgment

Judge NG when the continuous time until completing the malfunction criteria below becomes more than 1 second.

Judgment Value

Malfunction Criteria	Threshold Value
Battery voltage	> 10.9 V
Before and after starting the engine	After starting the engine
Positive crankcase ventilation diagnosis terminal voltage	High

Time Needed for Diagnosis: 1 second

Malfunction Indicator Light Illumination: Illuminates as soon as malfunction occurs.

Normality Judgment

Judge OK and clear NG when the malfunction criteria below is completed.

Judgment Value

Malfunction Criteria	Threshold Value
Battery voltage	> 10.9 V
Before and after starting the engine	After starting the engine
Positive crankcase ventilation diagnosis terminal voltage	Low

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 performed 3 times in a row

•	When “Clear Memory” was performed

FAIL SAFE

None

ECM OPERATION AT DTC SETTING

•	Memorize the freeze frame data. (For test mode $02)

•	Memorize the diagnosis value and trouble standard value. (For test mode $06)