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 under all engine operating conditions. During engine operation, the PCM calculates the average voltage of each knock sensors signal. If the knock sensor system is operating normally, the PCM should monitor KS signal voltages varying over 0.5 volt more than and less than 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
| • | None of the following DTCs are set. |
| - | Throttle position (TP) sensor |
| - | Vehicle speed sensor (VSS) |
| - | Crankshaft position (CKP) sensor |
| - | Mass air flow (MAF) sensor |
| - | Engine coolant temperature (ECT) sensor |
| • | The engine speed is between 1000 and 4000 RPM (VIN K). |
| • | The engine speed is between 1000 and 3000 RPM (VIN 1). |
| • | The throttle angle is more than 3 percent (VIN K). |
| • | The throttle angle is more than 15 percent (VIN 1). |
| • | The engine load is more than 20 percent (VIN K). |
| • | The engine load is more than 45 percent (VIN 1). |
| • | The engine coolant temperature is more than 75°C (167°F). |
| • | The maximum spark retard is less than 15 degrees. |
| • | The system voltage is more than 9 volts. |
Action Taken When the DTC Sets
The PCM stores conditions which were present when the DTC set as Failure Records only. This information will not be stored as Freeze Frame Records.
Conditions for Clearing the MIL/DTC
| • | The DTC becomes history when the conditions for setting the DTC are no longer present. |
| • | The history DTC clears after 40 malfunction free warm-up cycles. |
| • | The PCM receives a clear code command from the scan tool. |
Diagnostic Aids
Inspect for the following conditions:
Many situations may lead to an intermittent condition. Perform each inspection or test as directed.
Important: : Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.
| • | Loose terminal connection |
| - | Use a corresponding mating terminal to test for proper tension. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair. |
| - | Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair. |
| • | Damaged harness--Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair. |
| • | Inspect the powertrain control module (PCM) and the engine grounds for clean and secure connections. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair. |
If the condition is determined to be intermittent, reviewing the Snapshot or Freeze Frame/Failure Records may be useful in determining when the DTC or condition was identified.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This DTC indicates an internal PCM problem.
-
If sent here from symptoms, proceed with the diagnostic table.
-
This vehicle is equipped with a PCM which utilizes an electrically erasable programmable read-only memory (EEPROM). When the PCM is replaced, the new PCM must be reprogrammed.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On Board Diagnostic (OBD) System Check performed? | -- | ||
|
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.
Does the scan tool indicate DTC P0325 failed this ignition? | -- | |||
Does the scan tool indicate the 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 repair? | -- | -- | ||
5 |
Does the scan tool indicate the DTC P0325 test failed this ignition? | -- | System OK |
