Circuit Description
The knock sensor (KS) system detects for an engine detonation. The knock sensor produces an AC voltage signal. The amplitude and the frequency of the AC voltage signal is dependent upon the knock level being detected. This signal then travels to the KS module that is an internal part of the Powertrain Control Module (PCM). If knock is detected, the PCM will retard the spark timing based on the signal from the knock sensor.
Conditions for Setting the DTC
| • | Engine run time is greater than 20 seconds. |
| • | Engine Coolant Temperature (ECT) is greater than 56°C (131°F). |
| • | Engine speed is above 1600 RPM. |
| • | MAP is greater than 60 kPa. |
| • | Engine vacuum is less than 33 kPa. |
| • | The KS voltage and variation is not within normally expected ranges. |
| • | The above conditions are present for greater than 60 seconds. |
Action Taken When the DTC Sets
| • | The Malfunction Indicator Lamp (MIL) will illuminate. |
| • | The PCM will record operating conditions at the time the diagnostic fails. The Freeze Frame and Failure Records buffers will store this information. |
| • | A history DTC is stored |
| • | The PCM will default to a more conservative spark timing. |
Conditions for Clearing the MIL/DTC
| • | The malfunction indicator lamp (MIL) will turn OFF after 3 consecutive ignition cycles in which the diagnostic runs without a fault. |
| • | A history DTC will clear after 40 consecutive warm up cycles without a fault. |
| • | Use a scan tool to clear the DTCs. |
Diagnostic Aids
| • | Check and correct any abnormal engine noise before using the diagnostic table. |
| • | Thoroughly check any suspected circuitry for the following conditions: |
| - | Backed out terminals |
| - | Improper mating |
| - | Broken locks |
| - | Improperly formed connectors |
| - | Damaged terminals |
| - | Poor terminal to wiring connections |
| - | Physical damage to the wiring harness |
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
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The Powertrain OBD System Check prompts you to complete some basic checks and to store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data captured when the DTC set. The scan tool stores this data for later reference.
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If the conditions for the test as described above are met, a DTC P0325 will set and MIL will illuminate.
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If the engine has an internal knock or audible noise that causes a knocking type noise on the engine block, this is indication that the knock sensor may be responding to the noise.
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This step checks the internal resistance of the knock sensor or the wiring to the knock sensor.
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Any circuitry, that is suspected as causing the complaint, should be thoroughly checked for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wiring connections or physical damage to the wiring harness.
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The replacement PCM must be programmed and the crankshaft position system variation procedure must be preformed. Refer to the latest Techline procedure for PCM reprogramming and also refer to Crankshaft Position System Variation Learn for the Crankshaft Position System Variation Procedure.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | |||||||||
Does the Malfunction Indicator Lamp (MIL) illuminate? | -- | |||||||||
Listen to the engine while raising and lowering the engine speed. Is a knock or audible noise present? | -- | |||||||||
4 |
Is the action complete? | -- | -- | |||||||
Is the measured value within the specified value? | --90 k-110 k ohms | |||||||||
Was a repair necessary? | -- | |||||||||
Replace the PCM. Refer to the Powertrain Control Module Replacement for the replacement procedure. Is the action complete? | -- | -- | ||||||||
8 |
Was repair necessary? | -- | ||||||||
9 |
Was repair necessary? | -- | ||||||||
10 | Replace the Knock Sensor (KS). Refer to the Knock Sensor Replacement for the replacement procedure. Is the action complete? | -- | -- | |||||||
11 |
Does the scan tool indicate that this diagnosis has ran and passed? | -- | ||||||||
12 | Check to see if any DTCs are set. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to the Applicable DTC table | System OK |
