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For 1990-2009 cars only

DTC P0327 Knock Sensor (KS) Circuit With L19 or L29


Object Number: 33289  Size: SF
Engine Controls Components
Engine Controls Schematics
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The VCM uses the Knock Sensors (KS) in order to detect engine detonation. This allows the VCM to retard the Ignition Control (IC) spark timing based on the KS signal which the VCM receives. The circuitry within the knock sensor pulls down the VCM-supplied 5 volt signal, so that under a no knock condition the signal on the KS circuit measures about 1.3 volts. The knock sensors produce an AC signal that rides on the 1.3 volts DC. The amplitude and frequency of the AC signal are dependent upon the amount of the knock being experienced.

The VCM determines whether the knock is occurring by comparing the signal level on the KS circuit with a voltage level on the noise channel. The noise channel allows the VCM to reject any false knock signal by indicating the amount of normal engine mechanical noise present. The normal engine noise varies depending on the engine speed and load. When the VCM determines that an abnormally high noise channel voltage level is being experienced, a DTC P0326 sets. This DTC is a type B DTC.

Conditions for Setting the DTC

Knock Sensor Update Test

    • The timing retard is no more than 0 degrees.
    • System voltage is greater than 10 volts but no more than 17.1 volts
    • The Engine Coolant Temperature sensor is greater than 60°C (140°F)
    • Engine run time is greater than 2 minutes
    • Engine speed is between 500 RPM and 900 RPM

Active Noise Channel Test

    • No ECT DTCs set
    • No TP sensor DTCs set
    • The Knock Sensor update test is complete
    • The ECT is at least 60°C (140°F)
    • The engine speed is between 2000 RPM and 3000 RPM
    • The throttle angle is at least 5.8%
    • The engine has been running for at least 2 minutes
    • The system voltage is greater than 10 volts but no more than 17.1 volts
    • The timing retard is no more than 0 degrees.
    • The VCM is monitoring a ESC noise channel voltage level is below 0.5 volt

Action Taken When DTC Sets

    • The VCM will not illuminate the MIL
    • The VCM will store the conditions which were present when the DTC set as a Fail Records data only. This information will not store as Freeze Frame Data.
    • The VCM will use a calculated spark retard value in order to minimize the knock during the conditions when the knock is most likely to occur. The calculated value will vary based on the engine speed and load.

Conditions for Clearing the MIL/DTC

    • A history DTC will clear after 40 consecutive warm-up cycles have occurred without a fault
    • The scan tool Clear Info function or disconnecting the VCM battery feed can clear the DTC

Diagnostic Aids

Check for the following conditions:

    • A poor connection at the VCM -- Inspect the knock sensor and the VCM connectors for the following items:
       - Backed out terminals
       - Broken locks
       - Improperly formed or damaged terminals
    • A misrouted harness -- Inspect the knock sensor harness in order to ensure that it is not routed too close to high voltage wires such as spark plug leads.

Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

    • Improper knock sensor torque specification. Torque the knock sensor to 19 N·m (14 lbs ft).

Review the Failure Records vehicle mileage since the diagnostic test last failed in order to help determine how often the conditions that caused the DTC to set occur. This may assist in diagnosing the condition.

Test Description

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

  1. Ensures that the fault is present.

  2. Ensures that the knock sensor is capable of detecting detonation.

Step

Action

Value(s)

Yes

No

1

Important: Before clearing the DTCs use the scan tool in order to record the Freeze Frame and Failure Records for reference because the data will be lost when the Clear Info function is used.

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Operate the engine within the conditions specified in the diagnostic support Conditions for Setting the DTC.
  2. Using a scan tool, monitor the Specific DTC info for DTC P0327 until the DTC P0327 test runs.
  3. Observe the test results.

Does the scan tool indicate the DTC P0327 failed this ign?

--

Go to Step 4

Go to Step 3

3

  1. Turn ON the Ignition leaving the engine off.
  2. Review the scan tool Fail Records data.
  3. Record the scan tool Fail Records data.
  4. Operate the vehicle within the Fail Records conditions.
  5. Using a scan tool, monitor the Specific DTC info for the DTC P0327 until the DTC P0327 test runs.
  6. Observe the test results.

Does the scan tool indicate the DTC P0327 Failed This Ign?

--

Go to Step 4

Go to Diagnostic Aids

4

  1. Disconnect both KS sensor electrical connectors.
  2. Using a DVM J 39200 , measure the voltage between the KS signal circuit at the knock sensor harness connectors and ground.

Is the voltage approximately at the specified value?

5 V

Go to Step 5

Go to Step 8

5

Measure the resistance of each KS sensor by connecting the DVM between the KS sensor terminal and the engine block.

Is the resistance of each KS sensor near the specified value?

8K ohms

Go to Step 6

Go to Step 12

6

  1. Connect the DVM in order to monitor the voltage between the KS sensor terminal and the engine ground.
  2. Tap on the engine lift bracket while observing the signal indicated on the DVM.

Is any signal indicated on the DVM while tapping on the engine lift bracket?

--

Go to Step 7

Go to Step 9

7

  1. Check the KS signal circuit for a poor terminal connection at the knock sensor.
  2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Engine Electrical.

Was a problem found?

--

Go to Step 14

Go to Step 10

8

  1. Turn OFF the ignition.
  2. Disconnect the VCM.
  3. Turn ON the Ignition.
  4. Check the KS signal circuit between the VCM and the KS sensor connector for an open, a short to voltage, or a short to ground.
  5. If a problem is found, repair as necessary. Refer to Wiring Repairs in Engine Electrical.

Was a problem found?

--

Go to Step 14

Go to Step 10

9

Replace the Knock Sensor. Refer to Knock Sensor Replacement for the 5.0L, 5.7L, 7.4L.

Is action complete?

--

Go to Step 14

--

10

  1. Turn off the ignition.
  2. Disconnect the VCM.
  3. Check the KS signal circuit for a poor terminal connection at the VCM.
  4. If a problem is found, replace the faulty terminal.

Was a problem found?

--

Go to Step 14

Go to Step 11

11

  1. Check the KS module for not being fully seated or for incorrect installation.
  2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 14

Go to Step 12

12

  1. Replace the KS module.
  2. Operate the engine within the conditions specified in the diagnostic supporting text; Conditions for Setting the DTC.
  3. Using a scan tool, monitor the Specific DTC info for the DTC P0327 until the DTC P0327 test runs.
  4. Observe the test results.

Does the scan tool indicate DTC P0327 Failed This Ign?

--

Go to Step 13

Go to Step 14

13

Replace the VCM.

Important: If the VCM is faulty, reprogram the VCM. Refer to VCM Replacement/Programming .

Is the action complete?

--

Go to Step 14

--

14

  1. Using the scan tool, select the DTC and the Clear Info.
  2. Start the Engine.
  3. Idle at the normal operating temperature.
  4. Select the DTC and the Specific.
  5. Enter the DTC number which was set.
  6. Operate the vehicle within the conditions for setting this DTC as specified in the supporting text.

Does the scan tool indicate that this diagnostic ran and passed?

--

Go to Step 15

Go to Step 2

15

Using the scan tool, select the Capture Info and the Review Info.

Are any DTCs displayed that have not been diagnosed?

--

Go to The Applicable DTC Table

System OK

DTC P0327 Knock Sensor (KS) Circuit with L 30 or L 31


Object Number: 33289  Size: SF
Engine Controls Components
Engine Controls Schematics
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The VCM uses the Knock Sensors (KS) in order to detect engine detonation. This allows the VCM to retard the Ignition Control (IC) spark timing based on the KS signal which the VCM receives. The circuitry within the knock sensor pulls down the VCM-supplied 5 volt signal, so that under a no knock condition the signal on the KS circuit measures about 1.3 volts. The knock sensors produce an AC signal that rides on the 1.3 volts DC. The amplitude and frequency of the AC signal are dependent upon the amount of the knock being experienced.

The VCM determines whether the knock is occurring by comparing the signal level on the KS circuit with a voltage level on the noise channel. The noise channel allows the VCM to reject any false knock signal by indicating the amount of normal engine mechanical noise present. The normal engine noise varies depending on the engine speed and load. When the VCM determines that an abnormally high noise channel voltage level is being experienced, a DTC P0326 sets. This DTC is a type B DTC.

Conditions for Setting the DTC

Knock Sensor Update Test

    • The timing retard is no more than 0 degrees.
    • System voltage is greater than 10 volts but no more than 17.1 volts
    • The Engine Coolant Temperature sensor is greater than 60°C (140°F)
    • Engine run time is greater than 2 minutes
    • Engine speed is between 500 RPM and 900 RPM

Active Noise Channel Test

    • No ECT DTCs set
    • No TP sensor DTCs set
    • The Knock Sensor update test is complete
    • The ECT is at least 60°C (140°F)
    • The engine speed is between 2000 RPM and 3000 RPM
    • The throttle angle is at least 5.8%
    • The engine has been running for at least 2 minutes
    • The system voltage is greater than 10 volts but no more than 17.1 volts
    • The timing retard is no more than 0 degrees.
    • The VCM is monitoring a ESC noise channel voltage level is below 0.5 volt

Action Taken When DTC Sets

    • The VCM will not illuminate the MIL
    • The VCM will store the conditions which were present when the DTC set as a Fail Records data only. This information will not store as Freeze Frame Data.
    • The VCM will use a calculated spark retard value in order to minimize the knock during the conditions when the knock is most likely to occur. The calculated value will vary based on the engine speed and load.

Conditions for Clearing the MIL/DTC

    • A history DTC will clear after 40 consecutive warm-up cycles have occurred without a fault
    • The scan tool Clear Info function or disconnecting the VCM battery feed can clear the DTC

Diagnostic Aids

Check for the following conditions:

    • A poor connection at the VCM -- Inspect the knock sensor and the VCM connectors for the following items:
       - Backed out terminals
       - Broken locks
       - Improperly formed or damaged terminals
    • A misrouted harness -- Inspect the knock sensor harness in order to ensure that it is not routed too close to high voltage wires such as spark plug leads.

Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

    • Improper knock sensor torque specification. Torque the knock sensor to 19 N·m (14 lbs ft).

Review the Failure Records vehicle mileage since the diagnostic test last failed in order to help determine how often the conditions that caused the DTC to set occur. This may assist in diagnosing the condition.

Test Description

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

  1. Ensures that the fault is present.

  2. Ensures that the knock sensor is capable of detecting detonation.

Step

Action

Value(s)

Yes

No

1

Important: Before clearing the DTCs use the scan tool in order to record the Freeze Frame and Failure Records for reference because the data will be lost when the Clear Info function is used.

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Operate the engine within the conditions specified in the diagnostic support Conditions for Setting the DTC.
  2. Using a scan tool, monitor the Specific DTC info for DTC P0327 until the DTC P0327 test runs.
  3. Observe the test results.

Does the scan tool indicate the DTC P0327 failed this ign?

--

Go to Step 4

Go to Step 3

3

  1. Turn ON the Ignition leaving the engine off.
  2. Review the scan tool Fail Records data.
  3. Record the scan tool Fail Records data.
  4. Operate the vehicle within the Fail Records conditions.
  5. Using a scan tool, monitor the Specific DTC info for the DTC P0327 until the DTC P0327 test runs.
  6. Observe the test results.

Does the scan tool indicate the DTC P0327 failed this ign?

--

Go to Step 4

Go to Diagnostic Aids

4

  1. Disconnect both KS sensor electrical connectors.
  2. Using a DVM J 39200 , measure the voltage between the KS signal circuit at the knock sensor harness connectors and ground.

Is the voltage approximately at the specified value?

5 V

Go to Step 5

Go to Step 8

5

Measure the resistance of each KS sensor by connecting the DVM between the KS sensor terminal and the engine block.

Is the resistance of each KS sensor near the specified value?

100K ohms

Go to Step 6

Go to Step 12

6

  1. Connect the DVM in order to monitor the voltage between the KS sensor terminal and the engine ground.
  2. Tap on the engine lift bracket while observing the signal indicated on the DVM.

Is any signal indicated on the DVM while tapping on the engine lift bracket?

--

Go to Step 7

Go to Step 9

7

  1. Check the KS signal circuit for a poor terminal connection at the knock sensor.
  2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Engine Electrical.

Was a problem found?

--

Go to Step 14

Go to Step 10

8

  1. Turn OFF the ignition.
  2. Disconnect the VCM.
  3. Turn ON the Ignition.
  4. Check the KS signal circuit between the VCM and the KS sensor connector for an open, a short to voltage, or a short to ground.
  5. If a problem is found, repair as necessary. Refer to Wiring Repairs in Engine Electrical.

Was a problem found?

--

Go to Step 14

Go to Step 10

9

Replace the Knock Sensor. Refer to Knock Sensor Replacement for the 5.0L, 5.7L, 7.4L.

Is action complete?

--

Go to Step 14

--

10

  1. Turn off the ignition.
  2. Disconnect the VCM.
  3. Check the KS signal circuit for a poor terminal connection at the VCM.
  4. If a problem is found, replace the faulty terminal.

Was a problem found?

--

Go to Step 14

Go to Step 11

11

  1. Check the KS module for not being fully seated or for incorrect installation.
  2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 14

Go to Step 12

12

  1. Replace the KS module.
  2. Operate the engine within the conditions specified in the diagnostic supporting text; Conditions for Setting the DTC.
  3. Using a scan tool, monitor the Specific DTC info for the DTC P0327 until the DTC P0327 test runs.
  4. Observe the test results.

Does the scan tool indicate DTC P0327 Failed This Ign?

--

Go to Step 13

Go to Step 14

13

Replace the VCM.

Important: If the VCM is faulty, reprogram the VCM. Refer to VCM Replacement/Programming .

Is the action complete?

--

Go to Step 14

--

14

  1. Using the scan tool, select the DTC and the Clear Info.
  2. Start the Engine.
  3. Idle at the normal operating temperature.
  4. Select the DTC and the Specific.
  5. Enter the DTC number which was set.
  6. Operate the vehicle within the conditions for setting this DTC as specified in the supporting text.

Does the scan tool indicate that this diagnostic ran and passed?

--

Go to Step 15

Go to Step 2

15

Using the scan tool, select the Capture Info and the Review Info.

Are any DTCs displayed that have not been diagnosed?

--

Go to The Applicable DTC Table

System OK