Circuit Description
The knock sensor (KS) system is used to detect engine detonation. The knock sensor produces an AC voltage signal. The knock sensor sends this signal to the KS module. The amplitude and the frequency of the AC voltage signal depends upon the knock level being detected. The PCM will then retard the spark timing based on the signals from the KS module.
Conditions for Setting the DTC
| • | Engine run time is greater than 20 seconds. |
| • | Engine Coolant Temperature (ECT) is greater than 56°C (131°F). |
| • | KS instantaneous voltage is less than 1.0 V. |
| • | Engine speed is above 2200 RPM. |
| • | MAP is greater than 60 kPa. |
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 fault to base 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
Correct any abnormal engine noise before using the diagnostic table.
Check for an open ignition feed circuit.
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
-
The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored on the scan tool for later reference.
-
If the conditions for the test as described above are met, a DTC P0325 will set and MIL will illuminate.
-
If the engine has an internal knock or audible noise that causes a knocking type noise on the engine block, the knock sensor may be responding to the noise.
-
Checking the internal resistance of the knock sensor or the wiring to the knock sensor is OK.
-
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.
-
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 Powertrain Control Module (PCM) for the Crankshaft Position System Variation Procedure.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to | ||
Does the Malfunction Indicator Lamp (MIL) illuminate? | 120 seconds | |||
3 |
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? | -- | |||
5 | Repair the mechanical engine problem or a loose bracket or component. Is the action complete? | -- | -- | |
Is the measured value within the specified value? | 90 k-110 k ohms | |||
Check for a poor connection at the PCM connector, knock sensor signal circuit and repair as necessary. Was a repair necessary? | -- | |||
Replace the PCM. Is the action complete? | -- | -- | ||
9 | Check the knock sensor electrical connector for a poor connection and repair as necessary. Was a repair necessary? | -- | ||
10 | Check the knock sensor signal circuit for an open, a short to ground or voltage and repair as necessary. Was a repair necessary? | -- | ||
11 | Replace the Knock Sensor (KS). Is the action complete? | -- | -- | |
12 |
Does the scan to indicate that this diagnostic has ran and passed? | -- | ||
13 | Check if any additional DTCs are set. Are any DTCs displayed that have not been diagnosed? | -- | Go to applicable DTC table | System OK |
