P0325
DTC P0325 KNOCK SENSOR 1 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 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
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. 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
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". If 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:
- History (Not Present) fault : DTC occurred but has been cleared.
- Present fault : DTC is occurring at present time.
YES - 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, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.
NO - Go to next step as below
GROUND CIRCUIT INSPECTION
1. Ignition "OFF".
2. Disconnect Knock sensor and ECM connectors.
3. Measure resistance between terminals 1 of the sensor harness connector and 21 of the ECM harness connector.
Specification : Approx. 0 Ohm
4. Is resistance within the specification?
YES - Go to "Signal Circuit Inspection" procedure
NO - Check for an open in ground circuit. Repair as necessary and go to "Verification of Vehicle Repair" procedure
SIGNAL CIRCUIT INSPECTION
1. Check for short to ground in signal circuit
1. Measure resistance between terminal 2 of sensor harness connector and chassis ground.
Specification : Infinite
2. Is resistance within the specification?
YES - Go to next step as below
NO - Check signal circuit for short to ground. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
2. Check for short to power in signal circuit
1. Disconnect ECM connector.
2. Ignition "ON" & Engine "OFF".
3. Measure voltage between terminals 2 of sensor harness connector and chassis ground.
Specification : Approx. 0 V
4. Is voltage 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 open in signal harness
1. Ignition "OFF".
2. Measure resistance between terminals 2 of sensor harness connector and 22 of the ECM harness connector.
Specification : Approx. 0 ohm
3. Is resistance within the specification?
YES - Go to next step as below
NO - Repair as necessary and go to "Verification of Vehicle Repair" procedure.
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 next step as below
COMPONENT INSPECTION
1. Component resistance inspection
1. Measure resistance between terminals 1 and 2 of the sensor connector (Component side)
Specification : Approx. 5 Mohm 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 ECM 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.