P0325
Knock Sensor Circuit:
CIRCUIT OPERATION
- The knock sensor sends a signal voltage to the ECM (terminal 78)
TECHNICAL DESCRIPTION
- The knock sensor converts the vibration of the cylinder block into a voltage and outputs it. If there is a malfunction of the knock sensor, the voltage output will not change.
- The ECM
DTC SET CONDITIONS
Check Conditions
- Two seconds or more have passed since the starting sequence was completed.
- Engine speed is higher than 2,500 r/min.
Judgment Criteria
- Knock sensor output voltage (knock sensor peak voltage in each 1/2 turn of the crankshaft) has not changed more than 0.06 volt in the last consecutive 200 periods.
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Knock sensor failed.
- Open or shorted knock sensor circuit, or loose connector.
- ECM
- PCM failed.
DIAGNOSIS
Required Special Tools
- MB991502: Scan Tool (MUT-II)
STEP 1. Check connector B-108 at the knock sensor for damage.
Q: Is the connector in good condition?
YES: Go to Step 2.
NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 6.
STEP 2. Check the continuity at knock sensor harness side connector B-108.
1. Disconnect the connector B-108 and measure at the harness side.
2. Check for the continuity between terminal 2 and ground.
- Should be less than 2 ohm.
Q: Is the continuity normal?
YES: Go to Step 3.
NO: Repair harness wire between knock sensor connector B-108 terminal 2 and ground because of open circuit or harness damage. Then go to Step 6.
STEP 3. Check connector C-115 at ECM
Q: Is the connector in good condition?
YES: Go to Step 4.
NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 6.
STEP 4. Check for open circuit and short circuit to ground and harness damage between knock sensor connector B-108 terminal 1 and ECM connector C-115 terminal 78
Q: Is the harness wire in good condition?
YES: Go to Step 5.
NO: Repair it. Then go to Step 6.
STEP 5. Replace the knock sensor.
1. Replace the knock sensor.
2. Carry out a test drive.
3. Check the diagnostic trouble code (DTC).
Q: Is the DTC P0325 output?
YES: Replace the ECM or PCM. Then go to Step 6.
NO: The inspection is complete.
STEP 6. Using scan tool MB991502, check data list item 44: Ignition Coils and Ignition Power Transistor.
CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.
1. Connect scan tool MB991502 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Set scan tool MB991502 to the data reading mode for item 44, Ignition Coils and Ignition Power Transistor.
- Ignition timing with the knock sensor connector disconnected should retard more than the ignition timing with the knock sensor connector connected.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the ignition timing changes normally?
YES: The inspection is complete.
NO: Retry the troubleshooting.