GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2004 🢒 CTS 🢒 DTC 🢒 DTC P0327 or P0332

Circuit Description

The knock sensors (KS) produce an AC signal under all engine operating conditions. The powertrain control module (PCM) calculates the average voltage range of each KS signal. If the KS system is operating normally, the PCM should monitor the KS voltage varying above and below calculated average voltage. If the PCM detects a KS-1 signal or a KS-2 signal voltage within the calculated average range, a DTC will be set. DTC P0327 refers to the front knock sensor. DTC P0332 refers to the rear knock sensor.

Conditions for Running the DTC
    • DTCs P0117, P0118, P0121, P0122, P0123, P0125, P1114, P1115, P1121 or P1122 are not set.
    • The minimum noise level must be learned. The minimum noise level is learned when the following conditions are met:
       - The ECT must be greater than 60°C (140°F).
       - The engine RPM is between 475-975 for 10 seconds.
    •  Engine speed is between 1500 RPM and 3,000 RPM.
    • Map is less than 49 kPa.
    • Engine coolant temperature (ECT) is more than 60°C (140°F).
    • Throttle angle is more than 0  percent.
    • Engine run time is more than 10 seconds.
    • Ignition voltage is more than 10 volts.

Conditions for Setting the DTC

The PCM determines that this signal is less than the expected amount 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

       Important: If the knock sensor is dropped, it must be replaced.

    • Check the knock sensor for proper installation. A knock sensor that is loose or over torqued may cause the DTC to set.
    • 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.
    • For an intermittent, refer to Intermittent Conditions .

Test Description

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

  1. This verifies the malfunction is present.

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

    3.

  3. Tapping on the engine block will simulate an engine knock.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

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

1

Did you perform the Diagnostic System Check-Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

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

  1. Observe the Freeze Frame/Failure Records data for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. 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

3

  1. Remove the left engine sight shield.
  2. Disconnect the knock sensor (KS) jumper harness connector located on the left side of the intake manifold.
  3. Set the DMM to the 400K ohm scale.
  4. Measure the resistance of the affected KS using the DMM connected to battery ground.

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

93-107K ohms

Go to Step 4

Go to Step 6

4

  1. Connect the DMM between the affected KS signal circuit on the sensor side and a good ground.
  2. Set the DMM to the 400 mV AC hertz scale. Refer to Measuring Frequency in Wiring Systems.

    3. Important:  Do not tap on plastic engine components.

  3. Tap on the engine block 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

5
  1. Disconnect the PCM connector. Refer to Powertrain Control Module Replacement .
  2. Test the KS signal circuit between the PCM and the KS jumper harness connector for the following:
    3. • An open or high resistance
    • A short to voltage
    • A short to ground

Did you find and correct the condition?

--

Go to Step  12

Go to Step 9

6
  1. Remove the intake manifold. Refer to Intake Manifold Replacement in Engine Mechanical.
  2. Test for an open, high resistance or a short to ground in the signal circuit between the knock sensor jumper harness connector, located at the left side of the intake manifold and the KS connector. 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

7
  1. Inspect the KS signal circuit for a poor connection at the affected KS. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. 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 12

Go to Step 8

8

Replace the KS. Refer to Knock Sensor Replacement .

Did you complete the replacement?

--

Go to Step 12

--

9
  1. Inspect the KS signal circuit for a poor connection at the KS jumper harness connector. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. 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 12

Go to Step 10

10
  1. Inspect the KS signal circuit for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. 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  12

Go to Step 11

11

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

--

Go to Step 12

--

12
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. 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 13

Go to Step  2

13

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