For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provide an overview of each diagnostic category.

### DTC Descriptor

DTC P0327: Knock Sensor (KS) Circuit

### Circuit/System Description

The knock sensor (KS) enables the engine control module (ECM) to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The KS produces an AC voltage signal that varies depending on the vibration level during engine operation. The ECM adjusts the spark timing based on the amplitude and the frequency of the KS signal. The ECM receives the KS signal through a signal circuit. The ECM supples a ground circuit to the KS through a low reference circuit. The ECM also supplies a shielded ground circuit to the KS. The ECM learns a KS noise level at idle and uses calibrated values for the rest of the engine speed range. The ECM should monitor a normal KS signal within the noise channel. The circuits between the KS sensor and the ECM consist of the following circuits:

• | A KS signal

• | A low reference

• | A shielded ground

### Conditions for Running the DTC

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

• | The engine speed is more than 1,600 RPM.

• | The manifold absolute pressure (MAP) is between 10-50 kPa which depends on engine speed.

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

### Conditions for Setting the DTC

The ECM detects an incorrect KS signal for more than 4 seconds.

### Action Taken When the DTC Sets

DTC P0327 is a Type C DTC.

### Conditions for Clearing the DTC

DTC P0327 is a Type C DTC.

### Diagnostic Aids

The following conditions could also set this DTC:

• | 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 should be free of thread sealant. The KS mounting surface should be free of burrs, casting flash, and foreign material.

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

• | An electromagnetic interference (EMI) condition on the shielded ground circuit

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

• | Engine Control Module Connector End Views

• | Engine Controls Connector End Views

#### Description and Operation

Knock Sensor (KS) System Description

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

• | Scan Tool Data List

• | Scan Tool Data Definitions

• | Scan Tool Output Controls

### Circuit/System Verification

1. Start the engine. Observe the DTC information with a scan tool. DTC P0327 should not set.
2. If the vehicle passes the Circuit/System Verification Test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records List.

### Circuit/System Testing

Important: If the knock sensor lead is damaged in any way, replace the knock sensor.

1. Ignition OFF, disconnect the harness connector of the KS.
2. Ignition ON, connect a test lamp between the signal circuit of the KS and ground. The test lamp should not illuminate.

⇒ | If the test lamp illuminates, test the signal circuit for a short to voltage. If the circuits/connections test normal, replace the ECM.

3. Ignition ON, connect a test lamp between the signal circuit of the KS and B+. The test lamp should not illuminate.

⇒ | If the test lamp illuminates, test the signal circuit for a short to ground. If the circuits/connections test normal, replace the ECM.

4. Ignition OFF, connect a DMM between the signal circuit and the low reference circuit.
5. Test for 90-110K ohms between the signal circuit and the low reference circuit of the KS.

⇒ | If the resistance is not within the specified range, test the circuits for an open/high resistance. If the circuits/connections test normal, replace the ECM.

6. If all circuits/connections test normal, replace the KS sensor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Knock Sensor Replacement

• | Control Module References for engine control module replacement, setup, and programming