P0325 – Detonation Sensor System MMC Colt



OPERATION

  • The sensor signal is inputted to the engine-ECU (terminal No. 20) from the detonation sensor (terminal No. 2).

  • FUNCTION

  • The detonation sensor detects the vibration of the cylinder block caused by detonation waves, and inputs a signal to the engine-ECU.
  • In response to the signal, the engine-ECU provides controls to retard the ignition timing when the detonation occurs.

  • TROUBLE JUDGMENT

  • After 2 seconds have passed since the engine starting sequence was completed.
  • Engine speed is 2,500 r/min or higher.
  • Change of detonation sensor output voltage (detonation sensor peak voltage in each 1/2 turn of the crankshaft) has not been 0.06 V or more in the last consecutive 200 periods.

  • PROBABLE CAUSES

  • Failed detonation sensor
  • Open or shorted detonation sensor circuit, harness damage, or connector damage
  • Failed engine-ECU

  • DIAGNOSIS PROCEDURE

    STEP 1. Connector check: A-122 detonation sensor connector

    Q. Is the check result normal?

    STEP 2. Perform resistance measurement at A-122 detonation sensor connector.

  • Disconnect connector, and measure at harness side.
  • Resistance between terminal No. 1 and earth.
  • Q. Is the check result normal?

    STEP 3. Connector check: A-08 engine-ECU connector

    Q. Is the check result normal?

    STEP 4. Check harness between A-122 (terminal No. 1) detonation sensor connector and A-08 (terminal No. 21) engine-ECU connector.

  • Check earthing line for open circuit and damage.
  • Q. Is the check result normal?

    STEP 5. Replace detonation sensor.

  • After replacing the detonation sensor, re-check the trouble symptoms.
  • Q. Does trouble symptom persist?

    STEP 6. Connector check: A-08 engine-ECU connector

    Q. Is the check result normal?

    STEP 7. Check harness between A-122 (terminal No. 2) detonation sensor connector and A-08 (terminal No. 20) engine-ECU connector

  • Check output line for open/short circuit and damage.
  • Q. Is the check result normal?

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