Refer to Engine Controls Schematic
CKP, CMP, ICM and Knock Sensor
.
Circuit Description
The 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 sensor's signal. If the knock sensor system is operating normally, the PCM should monitor KS signal voltages varying over 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. |
| • | Engine speed is between 1000 and 5000 rpm. |
| • | Throttle angle is greater than 15%. |
| • | Engine load is greater than 40%. |
| • | Engine coolant temperature is greater than 60°C (153°F). |
| • | Maximum spark retard is less than 15°. |
| • | System voltage is between 9.0 and 18.0 volts. |
| • | Engine run time is greater 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. |
| • | Above conditions 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
Numbers below refer to the step numbers on the Diagnostic Table:
-
Ensures that the malfunction is present.
-
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 being replaced, the new PCM must be programmed.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On Board Diagnostic (OBD) System Check? | -- | ||
|
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 test result, does scan tool indicate DTC P0325 failed this ignition? | -- | |||
Does 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 repair? | -- | -- | ||
5 |
Does the scan tool indicate DTC P0325 test failed this ignition? | -- | System OK |
