For 1990-2009 cars

### Circuit Description

The knock sensor (KS) system enables the powertrain control module (PCM) to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The sensor is located on the intake side of the engine block. The sensor produces an AC voltage signal that varies at all engine speeds and loads. The PCM adjusts the spark timing based on the amplitude and the frequency of the KS signal. The PCM receives the KS signal through 2 isolated signal circuits. The PCM uses the KS signal to calculate the average voltage and then assigns a voltage range value. The PCM should monitor a normal KS signal within the assigned voltage range. If the PCM detects a KS signal outside of the assigned voltage range, or the KS signal is not present, this DTC will set.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0327 Knock Sensor 1 Circuit

### Conditions for Running the DTC

• | The engine speed is more than 1,800 RPM.

• | The engine load meets or exceeds a calibrated specification.

• | DTC P0327 runs continuously once the above conditions are met.

### Conditions for Setting the DTC

The KS signal is outside of the assigned voltage range or the signal is not present for one second.

### Action Taken When the DTC Sets

• | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.

• | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

### Conditions for Clearing the MIL/DTC

• | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.

• | A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

• | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

• | Clear the MIL and the DTC with a scan tool.

### Diagnostic Aids

• | Inspect the KS for physical damage. A KS that is dropped or damaged may cause a DTC to set.

• | Inspect the KS for proper installation. A KS that is loose or over torqued may cause a DTC to set. The KS and the KS fastener should be free of thread sealant. The KS mounting surface must be free of burrs, casting flash, and foreign material.

• | The KS should be clear of hoses, brackets, and engine electrical wiring.

• | For an intermittent condition, refer to Intermittent Conditions .

### Test Description

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

1. This step ensures that the malfunction is present.

2. This step tests for a KS that is shorted to ground

3. This step tests the KS for proper operation.

4. This step tests for a short to voltage on the KS signal circuits.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 | Important: If an engine mechanical noise can be heard, repair the condition before proceeding with this diagnostic. Refer to Symptoms - Engine Mechanical .

1. Observe the Freeze Frame/Failure Records for this DTC.
2. Turn the ignition OFF for 30 seconds.
3. Start the engine.
4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Does the DTC fail this ignition?

--

Go to Step 3

Go to Diagnostic Aids

3 |

1. Turn OFF the ignition.
2. Disconnect the knock sensor (KS).
3. Set the DMM to the ohm scale.
4. Measure the resistance from the KS signal terminal A to a good ground with the DMM.
5. Measure the resistance from the KS signal terminal B to a good ground with the DMM.

Does the DMM display OL for both terminals?

--

Go to Step 4

Go to Step 10

4 |

1. Connect the DMM between the terminals of the KS.
2. Set the DMM to the 400 mV AC hertz scale and wait for the DMM to stabilize at 0 Hz. Refer to Measuring Frequency .

Important: DO NOT tap on plastic engine components.

3. Tap on the engine block with a non-metallic object near the affected KS while observing the signal indicated on the DMM.

Does the DMM display a fluctuating frequency while tapping on the engine block?

--

Go to Step 5

Go to Step 10

5 |

1. Turn ON the ignition, with the engine OFF.
2. Measure the voltage at the KS signal circuit terminal A to a good ground with a DMM.
3. Measure the voltage at the KS signal circuit terminal B to a good ground with a DMM.

Does the DMM display a voltage above the specified value on either circuit?

4.2 V

Go to Step 6

Go to Step 7

6 |

1. Turn OFF the ignition
2. Disconnect the powertrain control module (PCM).
3. Test the KS signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 12

Go to Step 11

7 |

1. Turn OFF the ignition.
2. Disconnect the PCM.
3. Test the KS signal circuit for an open, for a high resistance, and for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 12

Go to Step 9

8 | Test for an intermittent and for a poor connection at the affected KS. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 10
9 | Test for an intermittent and for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 11
10 | Replace the affected KS. Refer to Knock Sensor 1 Replacement . Did you complete the replacement? | -- | Go to Step 12 | --
11 | Replace the PCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 12 | --
12 |

1. Clear the DTCs with a scan tool.
2. Turn the ignition OFF for 30 seconds.
3. Start the engine.
4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Does the DTC fail this ignition?

--

Go to Step 2

Go to Step 13

13 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle | System OK