Circuit Description
The powertrain control module (PCM) contains integrated knock sensor (KS) diagnostic circuitry. Input signals from the knock sensors are used to detect engine detonation, allowing the PCM to retard ignition control (IC) spark timing based on the amplitude and frequency of the KS signal being received. The knock sensors produce an AC signal during all engine operating conditions. During engine operation, the PCM calculates the average voltage of the knock sensor's signal. If the KS system is operating normally, the PCM should monitor the KS signal voltages that vary more than 0.5 volt above and below the calculated average voltage. If the PCM malfunctions in a manner which will not allow proper diagnosis of the KS circuits, DTC P0325 will set.
Conditions for Running the DTC
| • | No TP Sensor, VSS, CKP, MAF, or ECT DTCs are set. |
| • | The engine speed is between 1000--5000 RPM. |
| • | The throttle angle is more than 15 percent. |
| • | The engine load is more than 45 percent. |
| • | The engine coolant temperature is more than 60°C (153°F). |
| • | The maximum spark retard is less than 15 degrees. |
| • | The system voltage is more than 9.0 volts. |
| • | The engine run time is more than 30 seconds. |
Conditions for Setting the DTC
| • | The PCM detects a malfunction in the integrated knock sensor diagnostic circuitry which will not allow proper diagnosis of the knock sensor circuits. |
| • | The above condition is present for at least 1 second. |
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed. |
| • | The PCM will store conditions which were present when the DTC set as Freeze Frame/Failure Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed. |
| • | The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using a scan tool. |
Test Description
The numbers below refer to the step numbers on the diagnostic table:
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This step ensures that the malfunction is present.
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If you are sent here from Symptoms, proceed with the diagnostic table.
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This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On Board (OBD) System Check? | -- | ||
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Important : If a mechanical engine knock can be heard repair the engine mechanical problem before proceeding with this diagnostic. Refer to Engine Noise Diagnosis in Engine Mechanical.
Note the test result. Does the scan tool indicate DTC P0325 failed this ignition? | -- | |||
Does the scan tool indicate DTC P0325 test failed this ignition? | -- | Go to Diagnostic Aids | ||
|
Important : The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | -- | ||
5 |
Does the scan tool indicate DTC P0325 test failed this ignition? | -- | System OK |
