P0325 Knock Sensor 1 Circuit

COMPONENT LOCATION

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GENERAL DESCRIPTION
The knock sensor is attached to the cylinder block and senses engine knocking. The sensor contains a piezoelectric element that converts vibration (or noise) into voltage signal and sends this signal to ECM. With input signals from camshaft position and crankshaft position sensor, ECM can identify which cylinder is knocking. ECM filters vibrations and determines if the vibrations are knocking signal. The Engine Control Module (ECM) uses this signal to suppress knocking by retarding ignition timing. The ECM will set a code (Malfunction Indicator Lamp will Not turn on) if during two driving cycles the Knock sensor’s output voltage falls below minimum threshold. This code indicates an unexpected vibration is being read by the Knock sensor or ECM under normal engine operation.
DTC DESCRIPTION
Checking the range of input signal with a knock sensor under detecting condition, ECM senses open in knock sensor circuit or malfunction of sensor. If a knock signal or noise level is inputted without the specified value during standard duration, ECM sets P0325.
DTC DETECTING CONDITION
 
ItemDetecting ConditionPossible Cause
DTC Strategy
Signal short
1.
Poor connection
2.
Open in harness
3.
Knock sensor
4.
ECM
Enable Conditions
Pressure in intake manifold is normal
Engine speed ≥ 2200rpm
Threshold value
Knock Filtered Value < 1.0
Diagnosis Time
Continuous
MIL On Condition
NO MIL ON(DTC only)

 

DIAGNOSTIC CIRCUIT DIAGRAM

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SIGNAL WAVEFORM & DATA

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Fig.1) Normal data of knock sensor at ig on.
Fig.2) Normal waveform of knock sensor at ig on.
MONITOR GDS DATA
1.
Connect GDS to Data Link Connector(DLC).
2.
IG “ON”.
3.
Select “DTC” button, and then Press “DTC Status” to check DTC’s information from the DTCs menu.
4.
Read “DTC Status” parameter.

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5.
Is parameter displayed “Present fault”?
 

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â–¶ Go to “Terminal and Connector inspection” procedure.

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▶ Fault is intermittent caused by poor contact in the sensor’s and/or ECM’s connector or was repaired and ECM memory was not cleared. Thoroughly check connectors for looseness, poor connection, ending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary

 

TERMINAL AND CONNECTOR INSPECTION
1.
Many malfunctions in the electrical system are caused by poor harness and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2.
Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3.
Has a problem been found?
 

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â–¶ Repair as necessary and go to “Verification of Vehicle Repair” procedure .

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â–¶ Go to ” Signal Circuit Inspection ” procedure.
SIGNAL CIRCUIT INSPECTION
â–  Check open in harness
1.
IG “OFF” and disconnect knock sensor connector and ECM connector.
2.
Measure resistance between low signal terminal of knock sensor harness connector and knock sensor low signal terminal of ECM harness connector.
3.
Measure resistance between high signal terminal of knock sensor harness connector and knock sensor high signal terminal of ECM harness connector.
 Below 1Ω

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4.
Is the measured resistance within specification ?
 

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â–¶ If the problem is corrected after substituting with a known – good knock sensor, replace it. If the problem is pending, check for proper operating after substituting with a known – good ECM. and then if the problem is corrected, replace ECM and go to “Verification of Vehicle Repair” procedure.
   
 
There is a memory reset function on GDS that can erase optional parts automatically detected and memorized by ECM. Before or after testing ECM on the vehicle, use this function to reuse the ECM on the others

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â–¶ Repair open in harness

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