P0325
DTC P0325 KNOCK SENSOR / CIRCUITComponent 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 PCM. With input signals from camshaft position and crankshaft position sensor, PCM can identify which cylinder is knocking. PCM filters vibrations and determines if the vibrations are knocking signal. The Engine Control Module (PCM) uses this signal to suppress knocking by retarding ignition timing. The PCM 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 PCM under normal engine operation.
DTC DESCRIPTION
The PCM 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. In case the noise level is higher than the upper threshold or lower than the lower threshold, the DTC P0325 is set too.
DTC Detecting Condition:
Schematic Diagram:
MONITOR DTC STATUS
NOTE: If any codes relating to TPS or MAFS are stored, do ALL REPAIRS associated with those codes before proceeding with further troubleshooting.
1. Connect scan tool and select "Diagnostic Trouble Codes(DTCs)" mode.
2. Press F4(DTAL) to select DTC information from the DTCs menu.
3. Confirm that "DTC Readiness Flag" indicates "Complete". It not, drive the vehicle within conditions noted in the freeze frame data or enable conditions.
4. Read "DTC Status" parameter.
5. Is parameter displayed "History(Not Present) fault"?
NOTE:
1. History (Not Present) fault: DTC occurred but has been cleared.
2. Present fault: DTC is according at present time.
YES: Fault is intermittent caused by poor contact in the sensor's and/or the PCM's connector, which was repaired but PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.
NO: Go to next step as below.
TERMINAL AND CONNECTOR INSPECTION
1. Many malfunctions in the electrical system are caused by poor harness(es) 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?
YES: Repair as necessary and go to "Verification of Vehicle Repair" procedure.
NO: Go to "Ground Circuit Inspection" procedure.
GROUND CIRCUIT INSPECTION
1. Ignition "OFF".
2. Disconnect Knock sensor and PCM connectors.
3. Measure resistance between terminals 2 of the sensor harness connector and 54 of the PCM harness connector.
Specification : Approx.0 ohms
4. Is resistance within the specification?
YES: Go to "Signal Circuit Inspection" procedure.
NO: Check for an open in the ground circuit. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
SIGNAL CIRCUIT INSPECTION
1. Check for open in signal harness.
1. Measure resistance between terminals 1 of sensor harness connector and 10 of the PCM harness connector.
Specification : Approx. 0 ohms
2. Is resistance within the specification?
YES: Go to next step as below.
NO: Repair as necessary and go to "Verification of Vehicle Repair" procedure.
2. Check for short to ground in signal harness.
1. Measure resistance between terminal 1 of sensor harness connector and chassis ground.
Specification : Infinite
2. Is resistance within the specification?
YES: Go to next step as below.
NO: Repair as necessary and go to "Verification of Vehicle Repair" procedure.
3. Check for short to power in signal harness
1. Ignition "ON" & Engine "OFF".
2. Measure voltage between terminals 1 of sensor harness connector and chassis ground.
Specification Approx. 0 V
3. Is voltage within the specification?
YES: Go to "Component Inspection" procedure.
NO: Repair as necessary and go to "Verification of Vehicle Repair" procedure.
COMPONENT INSPECTION
1. Component resistance inspection.
1. Ignition Off.
2. Disconnect knock sensor connector.
3. Measure resistance between terminals 1 and 2 of the sensor connector(Component side).
Specification : Approx. 5 Mohms at 20°C (68 °F)
2. Output signal inspection.
1. Remove knock sensor from vehicle and secure (across mounting boss) in a shop vise.
2. Set up an oscilloscope as follows
Channel A (+): terminal 1 (-): terminal 2.
3. Rap on vise with a ball peen hammer while monitoring oscilloscope screen (there should be a spike of less than 1 volt with each hammer strike).
Specification : knock sensor send a voltage spike with hammer strikes
3. Installation torque inspection.
1. Check the installation torque of the knock sensor.
Specification : Approx. 16-28 N.m (160-250 kg.cm,11.8-18.4 lb.ft)
4. Has a problem been found?
YES: Check knock sensor for contamination, deterioration, or damage. Substitute with a known-good sensor and check for proper operation. If the problem is corrected, replace sensor and then go to "Verification of Vehicle Repair" procedure.
NO: Check for poor connection between PCM and component: backed out terminal, improper mating, broken locks or poor terminal to wire connection. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1. Connect scan tool and select "Diagnostic Trouble Codes(DTCs)" mode.
2. Press F4(DTAL) and confirm that "DTC Readiness Flag" indicates "Complete". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions.
3. Read "DTC Status" parameter.
4. Is parameter displayed "History(Not Present) fault"?
YES: System performing to specification at this time. Clear the DTC.
NO: Go to the applicable troubleshooting procedure.