For 1990-2009 cars

### Circuit Description

The DTC P0327 Knock Sensor (KS) Circuit Low Voltage diagnostic monitors the activity on the knock sensor circuit. The KS is used to detect engine detonation. The KS is constructed of a piezoelectric element which generates an AC signal when vibrated. Normal engine operation will cause the KS to generate a signal of a certain known frequency. When engine knock is present, the KS frequency changes which signals the PCM to retard ignition timing. By retarding the ignition timing, the engine detonation detected should be reduced.

### Conditions for Running the DTC

The engine is running.

### Conditions for Setting the DTC

The KS signal detected is below 0.90 volts for more than 10 seconds.

### Action Taken When the DTC Sets

• | The PCM illuminates the MIL.

• | The PCM stores the conditions which were present when the DTC set as Freeze Frame data.

### Conditions for Clearing the MIL/DTC

• | The PCM turns OFF the MIL on the third consecutive trip cycle during which the diagnostic has been run and the fault condition is no longer present.

• | The DTC clears after 40 consecutive warm-up cycles have occurred without a fault.

• | A DTC can be cleared by using the scan tool Clear DTC Information function.

### Diagnostic Aids

A loose KS can cause a loss of the KS signal. Check the KS for the proper torque.

An intermittent malfunction may be caused by a fault in the KS sensor electrical circuit. Inspect the wiring harness and the components for an intermittent condition. Refer to Intermittent Conditions .

Repair any electrical circuit faults that were found. Refer to Wiring Repairs in Wiring Systems.

The information included in the Freeze Frame data can be useful in determining the vehicle operating conditions present when the DTC first set.

### Test Description

The numbers below refer to the step numbers in the diagnostic table.

1. The Diagnostic System Check-Engine Controls prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

2. This step checks whether the DTC P0327 is the result of a hard failure or an intermittent condition. Operating the vehicle in Check mode enhances the diagnostic capabilities of the PCM.

3. This step checks the 5 volt reference from the PCM.

4. This step checks for the knock sensor signal.

5. Clearing the DTCs by removing the DOME fuse also clears the PCM long term memory. Using the scan tool to clear DTCs leaves the long term memory active. DTC emitting diagnostics may not run to completion as expected unless the long term memory is cleared. Removal of the DOME fuse also clears the time display of the radio. The DTC P0327 diagnostic can be monitored on the scan tool under the Not Ran Since Code Cleared selection in the DTC Information menu. If a DTC P0327 appears in the Not Ran Since Code Cleared list, the DTC P0327 diagnostic has not yet run. When the DTC P0327 does not appear in the Not Ran Since Code Cleared list, the DTC P0327 diagnostic has run. If the MIL is NOT illuminated, and there is no Pending DTC Status in DTC Information, the DTC P0327 diagnostic has passed. The DTCs MUST be cleared in order to view the Current Status of the Not Ran Since Code Cleared list. DO NOT forget that the Not Ran Since Code Cleared list only indicates that the test has run, not whether the test passed or failed. The DTC Information screen must be checked for Current or Pending status, in order to determine the outcome of the diagnostic test involved.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: Engine Controls Schematics
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | Go to Diagnostic System Check - Engine Controls
2 |

1. Perform the scan tool Clear DTC Information function.
2. Operate the vehicle within the Freeze Frame conditions as specified.

Does DTC P0327 set?

--

Go to Step 3

Go to Diagnostic Aids

3 |

1. Turn OFF the ignition.
2. Disconnect the knock sensor connector.
3. Probe the knock sensor terminal on the harness side with a digital multimeter (DMM) connected to ground.
4. Turn ON the ignition with the engine OFF.

Is the DC voltage within the specified value?

4-5 V

Go to Step 4

Go to Step 6

4 |

1. Turn OFF the ignition.
2. Reconnect the KS connector.
3. Backprobe the KS signal circuit at the PCM connector, terminal C2-3, with the DMM connected to ground.
4. Select DC voltage.
5. Start the engine.
6. Monitor the output of the KS signal with the engine running.

Is the voltage within the specified value?

0.90-3.98 V

Go to Diagnostic Aids

Go to Step 5

5 | Replace the knock sensor. Refer to Knock Sensor Replacement . Is the action complete? | -- | Go to Step 8 | --
6 |

1. Check for a short in the KS signal circuit.

Ensure that the terminal connection at the sensor is good.

2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and repair a wiring condition?

--

Go to Step 8

Go to Step 7

7 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 8 | --
8 |

1. Turn OFF the ignition.
2. Remove the DOME fuse for 30 seconds.
3. Install the DOME fuse.
4. Reset the radio clock time. Refer to Radio/Audio System Description and Operation in Entertainment.
5. Start the engine.
6. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text or until the DTC P0327 diagnostic test has run.

Does the DTC run and pass?

--

Go to Step 9

Go to Step 2

9 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List | System OK