For 1990-2009 cars

### Circuit Description

The knock sensor (KS) is a piezoelectric device that produces an AC voltage of different amplitude and frequency depending on the level of engine mechanical vibration. The KS system monitors the knock sensor in order to determine if detonation is present. If the KS system determines that excessive knock is present, the engine control module (ECM) retards the spark timing based on the signal from the KS system. The KS produces an AC signal when specific frequencies are detected. The ECM then retards the timing until knock is controlled.

In order to differentiate between normal engine noise and spark knock, the ECM samples the KS signal. The ECM samples the KS signal for a certain length of time under different engine speeds and loads during knock events. This sampling is used to determine a range of acceptable normal engine noise. If the ECM does not detect sufficient normal engine noise from the KS, this DTC sets.

### DTC Descriptors

This diagnostic procedure supports the following DTCs:

• | DTC P0327 Knock Sensor (KS) Circuit Low Voltage Bank 1

• | DTC P0332 Knock Sensor (KS) Circuit Low Voltage Bank 2

### Conditions for Running the DTC

• | Before the ECM can report DTC P0327 or P0332 failed, DTCs P0324, P0335, P0336, and P0338 must run and pass.

• | DTCs P0341, P0342, P0343, P0346, P0347, P0348, P0366, P0367, P0368, P0391, P0392, and P0393 are not set.

• | The engine coolant temperature (ECT) sensor is more than 60°C (140°F).

• | The engine speed is more than 2,000 RPM and steady.

• | Verify the proper performance of the cylinder.

• | DTCs P0327 and P0332 run continuously once the above conditions are met for approximately 20 seconds.

### Conditions for Setting the DTC

The ECM detects a KS signal voltage that is less than references KS signal voltage, which lasts for 100 pulse frequency.

### 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 4 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

• | Use the J 35616-A/BT-8637 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector.

• | The lower connector of the ECM is connector C1 and the upper connector of the ECM is connector C2. Refer to Engine Controls Component Views .

• | The KS must be torqued correctly. Refer Fastener Tightening Specifications .

• | The mounting between the sensor and engine must be free of burrs, casting flash, and foreign material.

• | The KS is clear from hoses, brackets, and engine wiring.

• | The normal KS signal voltage is 0.25 volts when the KS is disconnected.

• | 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 verifies a condition is present.

2. This step determines if there is a condition with the KS circuit. If the voltage increases when the circuit is grounded, this indicates that there is no condition with the KS circuit. If there is a condition with either circuit, the voltage will not increase when the circuits are connected to ground.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine 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 you can hear an engine knock, repair the engine mechanical condition before proceeding with this diagnostic. Refer to Symptoms - Engine Mechanical .

1. Start the engine.
2. Allow the engine to reach operating temperature.
3. Turn OFF all accessories.
4. Increase the engine speed to 2,000 RPM.
5. Observe the appropriate KS Signal voltage parameter with a scan tool.

Is the voltage more than the specified value?

0.75 V

Go to Step 3

Go to Step 4

3 |

1. Observe the Freeze Frame/Failure Records for this DTC.
2. Turn OFF the ignition 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.

Did the DTC fail this ignition?

--

Go to Step 4

Go to Diagnostic Aids

4 |

1. Disconnect the appropriate knock sensor (KS).
2. Connect a fused jumper wire between the signal circuit of the KS and a good ground.
3. Start the engine.
4. Observe the appropriate KS Signal voltage parameter with a scan tool.

Is the voltage more than the specified value?

1 V

Go to Step 6

Go to Step 5

5 |

1. Test the signal and the low reference circuit of the KS for the following conditions:

• | An open

• | The signal and the low reference circuit for being shorted together

• | The signal and the low reference circuit for being short together and shorted to ground

• | The signal and the low reference circuit for being short together and shorted to a voltage

2. Repair as necessary. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 10

Go to Step 7

6 | Test for an intermittent and for a poor connection at the KS. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 8
7 | Test for an intermittent and for a poor connection at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 9
8 | Replace the KS. Refer to the appropriate procedure:

• | Knock Sensor Replacement - Bank 1

• | Knock Sensor Replacement - Bank 2

Did you complete the replacement?

--

Go to Step 10

--

9 | Replace the ECM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 10 | --
10 |

1. Clear any DTCs with a scan tool.
2. Turn OFF the ignition 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.

Did the DTC fail this ignition?

--

Go to Step 2

Go to Step 11

11 | 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