Code No. P0326: Detonation Sensor Circuit Performance








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
  • 2 seconds or more have passed since the engine starting sequence was completed.
  • Engine speed is higher than 3,000 r/min.
  • Volumetric efficiency is 40 % or higher.
Judgement Criterion
  • Detonation sensor output voltage (detonation sensor peak voltage in each 1/2 turn of the crankshaft) has not changed more than 0.06 V in the last consecutive 200 periods.

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-34 detonation sensor connector

Q. Is the check result normal?
Go to Step 2 .
Repair or replace the connector.

STEP 2. Perform resistance measurement at B-34 detonation sensor connector.

  • Disconnect connector and measure at harness side.
  • Resistance between terminal No. 1 and earth.
OK: Continuity (2 Ω or less)

Q. Is the check result normal?
Go to Step 6 .
Go to Step 3 .

STEP 3. Connector check: B-29 engine-ECU connector

Q. Is the check result normal?
Go to Step 4 .
Repair or replace the connector.

STEP 4. Check harness between B-34 (terminal No. 1) detonation sensor connector and B-29 (terminal No. 42) engine-ECU connector.
note Before checking harness, check intermediate connector B-33, and repair if necessary.

  • Check earthing line for open circuit and damage.

Q. Is the check result normal?
Go to Step 5 .
Repair the damaged harness wire.

STEP 5. M.U.T.-III diagnosis code

  • Reconfirmation of diagnosis code.

Q. Is diagnosis code set?
Replace the engine-ECU.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

STEP 6. Connector check: B-29 engine-ECU connector

Q. Is the check result normal?
Go to Step 7 .
Repair or replace the connector.

STEP 7. Check harness between B-34 (terminal No. 2) detonation sensor and B-29 (terminal No. 25) engine-ECU connector.
note Before checking harness, check intermediate connector B-33, and repair if necessary.

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

Q. Is the check result normal?
Go to Step 8 .
Repair the damaged harness wire.

STEP 8. M.U.T.-III diagnosis code

  • Reconfirmation of diagnosis code.

Q. Is diagnosis code set?
Go to Step 9 .
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

STEP 9. M.U.T.-III diagnosis code

  • Reconfirm diagnosis code after replacement of detonation sensor.

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