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 provides an overview of each diagnostic category.

### DTC Descriptors

DTC P0324: Knock Sensor (KS) Module Performance
DTC P0325: Knock Sensor (KS) Circuit Bank 1
DTC P0326: Knock Sensor (KS) Performance
DTC P0327: Knock Sensor (KS) Circuit Low Voltage Bank 1
DTC P0328: Knock Sensor (KS) Circuit High Voltage Bank 1
DTC P0330: Knock Sensor (KS) Circuit Bank 2
DTC P0332: Knock Sensor (KS) Circuit Low Voltage Bank 2
DTC P0333: Knock Sensor (KS) Circuit High Voltage Bank 2

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Knock Sensor Signal | P0327, P0328, P0332, P0333 | P0325, P0330 | P0327, P0332 | P0326

### Circuit/System Description

The knock sensor (KS) system 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 ECM monitors 2 separate KS, one on each side of the engine block. Each KS produces an AC voltage that varies, depending on the vibration levels detected during engine operation. The ECM receives the KS signal through 2 isolated signal circuits for each KS. The ECM adjusts the spark timing based on the amplitude and frequency of each KS signal.

### Conditions for Running the DTC

#### P0324

This DTC runs continuously when the engine speed is greater than or equal to 1,500 RPM and the engine load is greater than a calibrated amount.

#### P0326

This DTC runs continuously when:

• | The engine speed is greater than or equal to 500 RPM.

• | The MAP is greater than 60 kPa.

• | DTCs P0120, P0121, P0122, or P0123 are not set.

#### P0325, P0327, P0328, P0330, P0332, and P0333

The DTCs run continuously when:

• | The engine coolant temperature (ECT) is greater than -40°C (-40°F).

• | The engine run time is greater than 1 second.

• | The power take-off (PTO) is not active.

### Conditions for Setting the DTC

#### P0324

The ECM has detected an internal circuitry fault.

#### P0325 and P0330

The KS signal circuits are open or shorted together for 5 seconds.

#### P0326

• | The KS signal indicates an engine knock is present.

• | The ECM has commanded the spark retard to a value, which is more than the calibrated value, for a specific engine load and speed.

• | The above conditions exist for more than 5 seconds.

#### P0327, P0328, P0332, and P0333

The KS signal circuits are shorted to voltage or ground.

### Action Taken When the DTC Sets

• | DTC P0324 is a Type A DTC.

• | DTCs P0325, P0326, P0327, P0328, P0330, P0332, and P0333 are Type B DTCs.

• | The ignition timing is retarded to reduce the potential of engine damaging spark knock.

### Conditions for Clearing the DTC

• | DTC P0324 is a Type A DTC.

• | DTCs P0325, P0326, P0327, P0328, P0330, P0332, and P0333 are Type B DTCs.

### 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 mounting surface should be free of burs, casting flash, and foreign material.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Electronic Ignition (EI) System Description

#### Electrical Information Reference

• | Testing for Intermittent Conditions and Poor Connections

• | Circuit Testing

• | Wiring Repairs

• | Connector Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

#### Special Tools

J 35616 GM Approved Terminal Test Kit

### Circuit/System Testing

#### P0324

Important: If DTC P0325, P0326, P0327, P0328, P0330, P0332, or P0333 are also set, diagnostics those DTCs first.

DTC P0324 indicates an internal control module circuitry failure. Replace the ECM.

#### P0325, P0327, P0328, P0330, P0332, P0333

1. Ignition ON, engine OFF.
2. Disconnect the appropriate KS harness connector.
3. Measure for 2-3 volts between each of the following circuits and ground on the ECM side of the harness connector:

• | The KS signal circuit, terminal A

• | The KS signal circuit, terminal B

⇒ | If less than the specified range, test the circuits for a short to ground or an open/high resistance. If the circuits test normal, replace the ECM.

⇒ | If greater than the specified range, test the circuits for a short to voltage. If the circuits test normal, replace the ECM.

4. If all circuits test normal, replace the KS.

#### P0326

| Important: If DTC P0325, P0327, P0328, P0330, P0333, P0335, or P0336 are also set, diagnostics those DTCs first.

• | Inspect for a loose or broken engine mount, engine mounted accessory, or accessory mounting bracket.

• | Inspect for excessive engine mechanical noise. Refer to Symptoms - Engine Mechanical.

### Component Testing

1. Connect a DMM to both KS signal circuits, terminals A and B, at the KS.
2. Set the DMM to the 400 mV AC hertz scale and wait for the DMM display to stabilize at 0 Hz.

Important: DO NOT tap on plastic engine components.

3. Tap on the engine block with a non-metallic object near the KS while observing the signal indicated on the DMM.
4. The DMM should display a fluctuating frequency while tapping on the engine block.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Knock Sensor Replacement

• | Engine Control Module Replacement

• | Engine Control Module Programming and Setup