DTC P0327 or P0332. GMC Truck GMC C-Series Medium Duty Truck C6/C7/C8 2002

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2002 🢒 GMC C-Series Medium Duty Truck C6/C7/C8 🢒 DTC 🢒 DTC P0327 or P0332

Circuit Description

The knock sensors (KS) produce an AC signal when specific frequencies are detected. When the engine operates, the powertrain control module (PCM) learns a minimum and maximum frequency of noise of normal engine operation. The KS system monitors both knock sensors in order to determine if knock is present. If the KS system determines that excessive knock is present, the PCM retards the spark timing based on the signals from the KS system. The PCM then retards the timing until no knock is present. When the PCM detects a frequency that is less than or more than a defined range, DTC P0327 will set for a failure in KS 1 which is located on bank 1 on the drivers side of the engine or DTC P0332 will set for a failure in KS 2 which is located on bank 2 on the passenger side of the engine.

Conditions for Running the DTC

•	DTCs P0107, P0108, P0117, P0118, P0125, P1114, or P1115 are not set.

•	The engine speed is between 1,600-3,000 RPM.

•	The manifold absolute pressure (MAP) is less than 45 kPa (13.3 in hg).

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

•	The engine run time is more than 20 seconds.

•	The ignition voltage more than 10 volts.

Conditions for Setting the DTC

The PCM determines that this frequency is less than or more than the expected amount for 3 seconds or more.

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 3 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

Check the knock sensor for proper installation. A knock sensor that is loose or over torqued may cause either DTC to set.

For an intermittent, refer to Intermittent Conditions .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

This verifies the malfunction is present.

This test will isolate the knock sensor from the rest of the circuit.

Tapping on the engine block near the appropriate knock sensor will simulate an engine knock.

Step

Action

Values

Yes

Schematic Reference: Engine Controls Schematics

Did you perform the Diagnostic System Check-Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

Important: If an engine knock can be heard, repair the engine mechanical condition before proceeding with this diagnostic.

Observe the Freeze Frame/Failure Records data for this DTC.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the engine within the Conditions for Running the DTC as close to the Freeze Frame/Failure Records data that you observed.

Does the scan tool indicate that this diagnostic failed this ignition?

Go to Step 3

Go to Diagnostic Aids

Turn the ignition OFF.
Disconnect the knock sensor harness of the appropriate knock sensor.
Set the DMM to the 400K-ohm scale.
Measure the resistance of the appropriate knock sensor using the DMM connected to battery ground.

Is the resistance of the knock sensor within the specified range?

93-107 Kohms

Go to Step 4

Go to Step 6

With the DMM still connected, set the DMM to the 400 mV AC hertz scale. Refer to Measuring Frequency in Wiring Systems.

Important: DO NOT tap on plastic engine components.

Tap on the engine block near the appropriate knock sensor while observing the signal indicated on the DMM.

Is any signal indicated on the DMM while tapping on the engine block near the knock sensor?

Go to Step 5

Go to Step 6

Disconnect the PCM connector. Refer to Powertrain Control Module Replacement .
Refer to Circuit Testing in Wiring Systems. Test the KS signal circuit between the PCM and the knock sensor connector for the following conditions:

•

An open

•	A short to voltage

•	A short to ground

Did you find and correct the condition?

Go to Step 9

Go to Step 7

Replace the knock sensor. Refer to Knock Sensor 1 Replacement or Knock Sensor 2 Replacement .

Did you complete the replacement?

Go to Step 9

Inspect the KS signal circuit for a poor connection at the PCM or the knock sensor harness connector. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
If you find a poor connection, repair the connector as necessary. Refer to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 9

Go to Step 8

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

Go to Step 9

Use the scan tool in order to clear the DTCs.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC run and pass?

Go to Step 10

Go to Step 2

With a scan tool, observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

Go to Diagnostic Trouble Code (DTC) List

System OK