DTC P0327 or P0332. Chevrolet Chevy Suburban

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 2003 🢒 Chevy Suburban - 4WD 🢒 Engine 🢒 Engine Controls - 4.8L, 5.3L, and 6.0L 🢒 DTC P0327 or P0332

Circuit Description

The knock sensor (KS) system enables the powertrain control module (PCM) to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The system uses two KS located under the intake manifold. KS 1 is located at the front of the engine. KS 2 is located at the back of the engine. Each KS produces an AC voltage that varies depending on the vibration level during engine operation. The PCM adjusts the spark timing based on the amplitude and frequency of the KS signal. The PCM receives a signal from each KS through a signal circuit. The KS ground is supplied by the engine block through the sensor housing. The PCM uses each KS signal to calculate an average voltage range value. If the KS system is operating normally, the PCM should monitor the KS voltage varying above and below the voltage range. If the PCM detects the KS signal voltage within the voltage range, or the KS signal is not present, a DTC will set. DTC P0327 refers to the front KS. DTC P0332 refers to the rear KS.

Conditions for Running the DTC

•	DTCs P0117, P0118, or P0125 are not set.

•	The minimum noise level must be learned. The minimum noise level is learned when the following conditions are met:

-	The engine coolant temperature (ECT) must be greater than 60°C (140°F).

-	The engine speed is between 475-975 RPM for 10 seconds.

•	The engine speed is between 1,500-3,000 RPM.

•	The manifold absolute pressure (Map) is less than 49 kPa.

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

•	The throttle angle is more than 0 percent.

•	The engine run time is more than 10 seconds.

•	The ignition voltage is more than 10 volts.

Conditions for Setting the DTC

•	The PCM detects that the KS signal is within the calculated voltage range or the KS signal is not present.

•	The above conditions are met for more than 9 seconds.

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

•	If DTCs P0327 and P0332 are set at the same time, inspect for poor connections at the KS harness jumper, located at the left rear side of the intake manifold.

•	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.

•	For an intermittent condition, refer to Intermittent Conditions .

Test Description

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

This step ensures that the malfunction is present.

This step tests the KS and the KS jumper harness for an open or a short to ground.

Tapping on the engine block will simulate an engine knock.

Step

Action

Values

Yes

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module Connector End Views

Did you perform the Diagnostic System Check-Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

Important: If an engine mechanical noise can be heard, repair the condition before proceeding with this diagnostic. Refer to Symptoms - Engine Mechanical in Engine Mechanical - 4.8L, 5.3L, and 6.0L.

Observe the Freeze Frame/Failure Records for this DTC.
Turn OFF the ignition for 30 seconds.
Start the engine.
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.

Does the DTC fail this ignition?

Go to Step 3

Go to Diagnostic Aids

Remove the left engine sight shield. Refer to Upper Intake Manifold Sight Shield Replacement in Engine Mechanical - 4.8L, 5.3L, and 6.0L.
Disconnect the knock sensor (KS) jumper harness connector located on the left side of the intake manifold.
Set the DMM to the 400 K-ohm scale.
Measure the resistance from the affected KS signal circuit on the sensor side of the KS jumper harness connector to a good ground with the DMM.

Is the resistance within the specified range?

93-107K ohms

Go to Step 4

Go to Step 6

With the DMM still connected, set the DMM to the 400 mV AC hertz scale.

Important: Do not tap on plastic engine components.

Tap on the engine block with a nonmetallic object near the affected KS while observing the signal indicated on the DMM.

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

Go to Step 5

Go to Step 7

Disconnect the PCM.
Test the affected KS signal circuit between the PCM and the KS jumper harness connector for the following conditions:

•

An open

•	A short to ground

•	A short to voltage

•	A high resistance

•	Refer to Testing for Continuity , Testing for Short to Ground , or Testing for a Short to Voltage in Wiring Systems.

Did you find and correct the condition?

Go to Step 12

Go to Step 8

Remove the intake manifold. Refer to Intake Manifold Replacement in Engine Mechanical 4.8L, 5.3L, 6.0L.
Test the KS signal circuit between the KS jumper harness connector and the KS connector for the following conditions:

•

An open

•	A short to ground

•	High resistance

•	Refer to Testing for Continuity or Testing for Short to Ground in Wiring Systems.

Did you find and correct the condition?

Go to Step 12

Go to Step 7

Test for an intermittent and for a poor connection at the affected KS. Refer to Testing for Intermittent Conditions and Poor Connections or Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 12

Go to Step 10

Test for an intermittent and for a poor connection at the KS jumper harness connector. Refer to Testing for Intermittent Conditions and Poor Connections or Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 12

Go to Step 9

Test for an intermittent and for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections or Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 12

Go to Step 11

Replace the affected KS. Refer to Knock Sensor Replacement .

Did you complete the repair?

Go to Step 12

Replace the PCM. Refer to Powertrain Control Module Replacement .

Is the action complete?

Go to Step 12

Clear the DTCs with a scan tool.
Turn OFF the ignition for 30 seconds.
Start the engine.
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.

Does the DTC fail this ignition?

Go to Step 2

Go to Step 13

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

Go to Diagnostic Trouble Code (DTC) List

System OK