Powertrain Management
DTC P0325, P0327, P0328, P0330, P0332, or P0333 (With Heavy Duty L96)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC P0325
-
Knock Sensor (KS) Circuit Bank 1
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/System Description
The knock sensor 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 knock sensor 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 knock sensor signal. The ECM receives the knock sensor signal through 2 isolated signal circuits for each bank. The ECM learns a minimum knock sensor noise level for all of the engine speed ranges. The ECM monitors for a normal knock sensor signal. The ECM monitors the internal knock sensor processor by verifying a 20 KHz signal generated on the output circuit is detected on the return circuit.
Conditions for Running the DTC
P0325 and P0330
* Engine speed is between 400-8,500 RPM.
* Engine is running at least 4 S.
* The ECT is warmer than -40°C (-40°F).
* The IAT is warmer than -40°C (-40°F).
* The DTCs run continuously when the above conditions are met.
P0327, P0328, P0332, and P0333
* Engine speed is less than 8,500 RPM.
* The DTCs run continuously when the above conditions are met.
Conditions for Setting the DTC
P0325 and P0330
The ECM detects that a knock sensor signal circuit is open.
P0327 and P0332
The ECM detects that a knock sensor signal circuit is shorted to ground.
P0328 and P0333
The ECM detects that a knock sensor signal circuit is shorted to voltage.
Action Taken When the DTC Sets
* DTCs P0325, P0327, P0328, P0330, P0332, and P0333 are Type B codes.
* The ignition timing is retarded to reduce the potential of engine damaging spark knock.
Conditions for Clearing the DTC
DTCs P0325, P0327, P0328, P0330, P0332, and P0333 are Type B codes.
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 burrs, casting flash, and foreign material.
* The KS must be clear of hoses, brackets, and engine electrical wiring.
Reference Information
Schematic Reference
Engine Controls Schematics (except L96) [1][2]Electrical DiagramsEngine Controls Schematics (L96) [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views 1-2 Shift Solenoid (SS) Valve (M30)
Description and Operation
Electronic Ignition System Description Description and Operation
Electrical Information Reference
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Circuit Testing Circuit Testing
* Wiring Repairs Wiring Repairs
* Connector Repairs Connector Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Control Module References for scan tool information
Special Tools
J 35616 GM Approved Terminal Test Kit
Circuit/System Verification
1. Engine idling, observe the DTC information with a scan tool. DTC P0325, P0327, P0328, P0330, P0332, or P0333 should not set.
2. Engine idling, move the related harnesses and connectors for the KS circuits while observing the scan tool Knock Retard and Total Knock Retard parameters. The parameters should remain steady with no abrupt changes.
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
1. Verify the appropriate B68 KS is properly tightened, refer to Fastener Tightening Specifications Fastener Tightening Specifications.
• If not the specified value, correct the condition as appropriate.
2. Ignition OFF, disconnect the appropriate B68 KS.
3. Ignition OFF, with appropriate length jumper wires, connect the B68A KS1 harness to the B68B KS2 sensor and the B68B KS2 harness to the B68A KS1 sensor.
4. Monitor the DTCs using a scan tool. Operate the vehicle within the conditions for running the DTC. Verify the fault does not follow the sensor in question.
• If the fault follows the sensor in question, replace the appropriate B68 KS.
5. Ignition OFF, remove the jumper wires from the previous step.
6. Ignition ON, measure for 1-4 V between each of the following circuits and ground on the K20 ECM side of the harness connector:
* The B68 KS signal circuit, terminal A or 1
* The B68 KS signal circuit, terminal B or 2
• 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 K20 ECM.
• If greater than the specified range, test the circuits for a short to voltage. If the circuits test normal, replace the K20 ECM.
7. If all circuits test normal, replace the K20 ECM.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Knock Sensor 1 Replacement Knock Sensor 1 Replacement
* Knock Sensor 2 Replacement Knock Sensor 2 Replacement
* Control Module References Control Module References for ECM replacement, programming, and setup.