Code No. P0327: Detonation Sensor Circuit Low Input


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 Condition
  • More than 2 seconds have passed since the engine starting sequence was completed.
Judgement Criterion
  • Detonation sensor output voltage is less than 0.5 V for 2 seconds.

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-26 engine-ECU connector and B-30 detonation sensor connector

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

STEP 2. Check harness between B-30 (terminal No. 1) detonation sensor connector and B-26 (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-30 (terminal No. 2) detonation sensor and B-26 (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.