For 1990-2009 cars
Engine Controls Components
Ignition Controls
OBD II Symbol Description Notice
Engine Controls Connector End Views
Handling ESD Sensitive Parts Notice

### Circuit Description

The knock sensor system detects for an engine detonation. The knock sensor produces an AC voltage signal. This signal then travels to the KS module that is an internal part of the PCM. The amplitude and the frequency of the AC voltage signal is dependent upon the knock level being detected. Then, the PCM will retard the spark timing based on the signals from the KS module.

### Conditions for Setting the DTC

• | The engine run time is greater than 20 seconds.

• | The Engine Coolant Temperature (ECT) is greater than 56°C (133°F).

• | The KS voltage is less than 1.0 V or greater than 4.99 V.

• | The engine speed is above 2200 RPM.

• | DTC(s) P0107, P0108 are not set.

• | The MAP is greater than 60 kPa.

• | 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. This information will store in the Freeze Frame and Failure Records buffers.

• | A history DTC stores.

• | The coolant fan turns ON.

• | The PCM will default to 6 degrees timing.

### Conditions for Clearing the MIL/DTC

• | The MIL will turn OFF after three 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.

• | The MIL/DTCs can be cleared by using the scan tool.

### 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.

1. 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.

2. If the conditions for the test as described above are met, a DTC P0325 will set and MIL will illuminated.

3. 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.

4. Checking the internal resistance of the knock sensor or the wiring to the knock sensor is OK.

5. 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.

6. 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 the Crankshaft Position System Variation Procedure.

#### DTC P0325-Knock Sensor (KS) Circuit

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 |

1. Start the engine.
2. Install a scan tool.
3. Clear the DTCs.
4. Operate the vehicle within the Conditions and Conditions For Setting The DTC as noted.

Does the Malfunction Indicator Lamp (MIL) illuminate?

120 seconds

Go to Step 4

Go to Step 3

3 |

1. Turn the ignition switch ON, with the engine OFF.
2. Review the Freeze Frame data and note the parameters.
3. Operate the vehicle within the Conditions and Conditions For Setting The DTC as noted.

Does the Malfunction Indicator Lamp (MIL) illuminate?

--

Go to Step 4

Go to Step 12

4 | Listen to the engine while raising and lowering the engine speed. Is a knock or audible noise present? | -- | Go to Step 5 | Go to Step 6
5 | Repair the mechanical engine problem or a loose bracket or component. Is the action complete? | -- | Go to Step 12 | --
6 |

1. Turn the ignition switch OFF.
2. Disconnect the PCM electrical connectors at the PCM.
3. Connect a DVM to ground, Measure the resistance of the knock sensor through the knock sensor signal circuit.

Is the measured value within the specified value?

90 k-110 k ohms

Go to Step 7

Go to Step 9

7 | Check for a poor connection at the PCM connector, knock sensor signal circuit and repair as necessary. Was a repair necessary? | -- | Go to Step 12 | Go to Step 8
8 | Replace the PCM. Is the action complete? | -- | Go to Step 12 | --
9 | Check the knock sensor electrical connector for a poor connection and repair as necessary. Was a repair necessary? | -- | Go to Step 12 | Go to Step 10
10 | Check the knock sensor signal circuit for an open, a short to ground, or voltage and repair as necessary. Was a repair necessary? | -- | Go to Step 12 | Go to Step 11
11 | Replace the Knock Sensor (KS). Is the action complete? | -- | Go to Step 12 | --
12 |

1. Using the scan tool, clear the DTCs.
2. Start the engine and idle at normal operating temperature.
3. Operate the vehicle within the conditions for setting this DTC as specified in the supporting text.

Does the scan to indicate that this diagnostic has ran and passed?

--

Go to Step 13

Go to Step 2

13 | Check if any additional DTCs are set. Are any DTCs displayed that have not been diagnosed? | -- | Go to applicable DTC table | System OK