For 1990-2009 cars
Engine Controls Components
Engine Controls Schematics
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

The PCM contains integrated Knock Sensor (KS) diagnostic circuitry. An input signal from the knock sensor is used to detect engine detonation, allowing the PCM to retard Ignition Control (IC) spark timing based on the amplitude and frequency of the KS signal being received. The knock sensor produces an AC signal under all engine operating conditions. During engine operation, the PCM calculates the average voltage of the knock sensor signal. If the knock sensor system is operating normally, the PCM will see KS signal voltage vary above and below the calculated voltage average. If the PCM detects KS input signal equal to the KS average voltage over 95% of a calibrated time, DTC P0327 will set.

### Conditions for Running the DTC

• | No TP sensor, VSS, CKP sensor, CMP sensor, MAF, or ECT DTCs are set.

• | Engine speed is between 1000 and 5000 RPM.

• | The engine has been running for a minimum of 30 seconds.

• | Throttle angle is greater than 15%.

• | Engine load is greater than 45%.

• | Engine coolant temperature is greater than 60°C (140°F).

• | Maximum spark retard is less than 15 degrees.

• | System voltage is greater than 9 volts.

### Conditions for Setting the DTC

The PCM detects a Knock Sensor signal voltage within the calculated average voltage range for at least 10 seconds.

### Action Taken When the DTC Sets

• | The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.

• | The PCM will store conditions which were present when the DTC set as Freeze Frame/Failure Records data.

### Conditions for Clearing the MIL/DTC

• | The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed.

• | The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

• | The DTC can be cleared by using a scan tool.

### Diagnostic Aids

Check for the following conditions:

• | Poor connection at PCM. Inspect knock sensor and PCM connectors for backed out terminals, broken locks, and improperly formed or damaged terminals.

• | Misrouted harness. Inspect the knock sensor harness to ensure that it is not routed too close to high voltage wires such as spark plug leads.

Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

### Test Description

1. Ensures that the malfunction is present.

2. If both the 24X Crank Sensor and the Cam signal are not present the KS signal will stop updating and set DTC P0327. The ignition positive voltage supply and the ground circuits need to be diagnosed using the DTC P0336.

3. If sent here from symptoms, proceed with the diagnostic table.

#### DTC P0327 - Knock Sensor Circuit

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to the Powertrain On Board Diagnostic (OBD) System Check
2 | Important: If a mechanical engine knock can be heard, repair the engine mechanical problem before proceeding with this diagnostic. Refer to Engine Noise Diagnosis (General Description) .

1. Operate the engine within conditions specified in Conditions for Setting the DTC.
2. Using a scan tool, monitor Specific DTC info for DTC P0327 until the DTC P0327 test runs.

Does scan tool indicate DTC P0327 failed this ignition?

--

Go to Step 5

Go to Step 3

3 | Using scan tool, monitor 24X crank sensor and the cam signal. Is 24X signal and Cam Signal present? | -- | Go to Step 4 | Go to DTC P0336 Crankshaft Position (CKP) Sensor Circuit
4 |

1. Turn ON the ignition switch, engine not running.
2. Review and record scan tool Fail Records data for DTC P0327.
3. Operate vehicle within Fail Records conditions.
4. Using a scan tool, monitor Specific DTC info for DTC P0327 until the DTC P0327 test runs.

Does the scan tool indicate DTC P0327 failed this ignition?

--

Go to Step 5

Go to Diagnostic Aids

5 |

1. Disconnect the PCM and the Knock Sensor.
2. Check the KS circuit for opens and shorts to ground.
3. If a problem is found, repair as necessary. Refer to Wiring Repairs .

Was problem found?

--

Go to step 8

Go to Step 6

6 |

1. Check the KS signal circuit for a poor terminal connection at the knock sensor.
2. If a problem is found, repair as necessary. Refer to Wiring Repairs .

Was problem found?

--

Go to Step 8

Go to Step 7

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

1. Review and record Fail Records data
2. Clear DTCs.
3. Operate the vehicle within Fail Records conditions.
4. Using a scan tool, monitor Specific DTC info for DTC P0327 until the DTC P0327 test runs.

Does the scan tool indicate DTC P0327 failed this ignition?

--

Go to Step 2

System OK