P0325 – Detonation Sensor System MMC Colt

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OPERATION

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

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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.

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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.

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PROBABLE CAUSES

Failed detonation sensor

Open or shorted detonation sensor circuit, harness damage, or connector damage

Failed engine-ECU

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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?