P0326 Knock Sensor 1 Circuit Range / Performance - Automotive Repair Guides & Equipment

COMPONENT LOCATION

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 short in knock sensor circuit or malfunction of sensor. If the average value of the knock signal is out of the threshold value during standard duration, ECM sets P0326.

DTC DETECTING CONDITION

Item

Detecting Condition

Possible Cause

DTC Strategy

Signal short

1.	Poor connection

2.	Short in harness

3.	Knock sensor

ECM

Enable Conditions

Pressure in intake manifold is normal

Engine speed ≥ 2200rpm

Threshold value

Knock Filtered Value < 5 or > 65

Diagnosis Time

Continuous

MIL On Condition

NO MIL ON(DTC only)

DIAGNOSTIC CIRCUIT DIAGRAM

SIGNAL WAVEFORM & DATA

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).

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.

Is parameter displayed “Present fault”?

	▶ Go to “Terminal and Connector inspection” procedure.
	▶ 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.

Has a problem been found?

	▶ Repair as necessary and go to “Verification of Vehicle Repair” procedure .
	▶ Go to ” Signal Circuit Inspection ” procedure.

SIGNAL CIRCUIT INSPECTION

■ Check short to battery in harness

1.	IG “OFF” and disconnect knock sensor connector.

IG “ON”.

3.	Measure voltage between low signal terminal of knock sensor harness connector and chassis ground.

Measure voltage between high signal terminal of knock sensor harness connector and chassis ground.

Specification : Approx. 1.5V

Is the measured voltage within specification ?

	▶ Go to “Check short to ground in harness” as follows.
	▶ Repair short to battery in harness, and go to “Verification of Vehicle Repair” procedure.

■ Check short to ground 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 chassis ground.

Measure resistance between high signal terminal of knock sensor harness connector and chassis ground.

Specification : Infinite

Is the measured resistance within specification ?

▶ 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

▶ Repair short to ground in harness

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