Code No. P0325: Detonation Sensor System








OPERATION



  • The sensor signal is input to the engine-ECU (terminal No. 25) from the detonation sensor (terminal No. 2).
  • The power voltage is earthed to the engine-ECU (terminal No. 42) from the detonation sensor (terminal No. 1).

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


Check Conditions
  • After 2 seconds pass from when the engine has completed the starting.
  • Engine speed is 3,000 r/min or more.
  • Manifold absolute pressure is more than 35 kPa.
Judgment Criterion
  • Change of detonation sensor output voltage (detonation sensor peak voltage in each 1/2 turn of the crankshaft) has not been 0.14 V or more in the last consecutive 200 periods.

FAIL-SAFE AND BACKUP FUNCTION



  • Fix the ignition timing with an allowance against detonation.

PROBABLE CAUSES



  • Failed detonation sensor
  • Open/short circuit or harness damage in detonation sensor circuit or loose connector contact
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: B-08 engine-ECU connector and B-14 detonation sensor connector

Q. Are the check results normal?
Go to Step 2.
Repair or replace the connector.

STEP 2. Check harness between B-14 (terminal No. 1) detonation sensor connector and B-08 (terminal No. 42) engine-ECU connector.

  • Check earthing line for open circuit and damage.

Q. Is the check result normal?
Go to Step 3.
Repair the damaged harness wire.

STEP 3. Check harness between B-14 (terminal No. 2) detonation sensor and B-08 (terminal No. 25) engine-ECU connector.

  • Check output line for open/short circuit and damage.

Q. Is the check result normal?
Go to Step 4.
Repair the damaged harness wire.

STEP 4. M.U.T.-III diagnosis code

  • Reconfirmation of diagnosis code.

Q. Is diagnosis code set?
Go to Step 5.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

STEP 5. Replace the detonation sensor

  • After replacing the detonation sensor, reconfirm whether the diagnosis code is set.

Q. Is the diagnosis code set?
Replace the engine-ECU.
Check end.