2.
In case the output voltage is over 3.5V
a.
Possible cause : Short in harness check ECM internal problem.
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.
The ECM monitors the range of the analog input signal from knock sensor to check sensor failure that is short circuit or open circuit. If the difference between knock signal and noise level is smaller than the threshold during defined time period, the DTC P0325 is set.
Item | Detecting Condition | Possible cause |
Monitoring Strategy | ● Signal check high | ● Open circuit in signal line ● Short circuit in signal line ● Open circuit in ground line ● Faulty knock sensor |
● Signal check low | ||
● signal interruption | ||
● Retionality check | ||
Threshold value | ● Notnalized reference : > UNDKSNU f(nmot) ● Level of knock control | |
● Notnalized reference : < UNDKSNU f(nmot) ● Level of knock control | ||
● Intergator grasient : ≤ DKROFN f(measuring window length) ● Short circuit in signal line ● Open circuit in ground line ● Faulty knock sensor | ||
Enable Conditions | ● Nmot : > 2600rpm ● No dynamic condition ● Knock control active | |
● Function active ●Nmot : ≤ 5200rpm , > 1200rpm | ||
Diagnostic Time | ● > 3 times | |
MIL on condition | ● > 2 .5 sec |
Idle : 0 ~ 20˚BTDC
3000 rpm : 29 ~ 49˚ BTDC
This figures show the waveform measured at terminal 1 of knock sensor at idle.
Check if the output voltage of knock sensor at idle is 0.4V
In case the output voltage is over 3.5V
Possible cause : Short in harness check ECM internal problem.
This figures show the waveform measured at terminal 1 of knock sensor at idle.
Check if the output voltage of knock sensor at idle is 0.4V
In case the output voltage is over 3.5V
Possible cause : Short in harness check ECM internal problem.
In case there is no symptom and wrong data but DTC is shown
The problem may be intermittent so slightly shake the connector and harness vertically and horizontally to check if there is any data changes
If the data changes normally, the problem was intermittent so erase DTC and verify the same DTC reoccure.
Go to "Terminal and Connector inspection" procedure.
In case there is symptom and wrong data with DTC
Check open,short or connector’s connection for Knock sensor
Check the deterioration of Knock sensor performance.
Go to "Visual inspection" procedure.
