P0327

DTC P0327 Knock Sensor Noise Channel Low Voltage




Circuit Description
The VCM uses the knock sensor(s) (KS) in order to detect engine detonation. The VCM can retard ignition control (IC) spark timing based on the KS signal input when spark knock is detected.

The VCM monitors normal engine background noise during warm engine operation. It stores these noise values for comparison to the current knock sensor signal to help discriminate between normal engine noise and knock. The VCM must detect at least the minimum stored noise values or it will set DTC
P0327.

Conditions for Running the DTC
- No active ECT sensor DTCs
- No active TP sensor DTCs
- The timing retard is 0 degrees or less.
- System voltage is between 10 - 17.1 volts
- The ECT is greater than 60 °C (140 °F)
- The engine run time is greater than 2 minutes.
- The knock sensor noise is less than 3 counts.
- The engine speed is between 2,000 - 3,000 RPM.
- The throttle position is greater than 6 percent

Conditions for Setting the DTC
The difference between the actual noise value and the learned minimum noise value is less than 50 counts or more than 200 counts.

Action Taken When the DTC Sets
- The VCM illuminates the MIL (Malfunction Indicator Lamp) if a failure is detected during 2 consecutive key cycles.
- The VCM will set the DTC and records the operating conditions at the time the diagnostic fails. The VCM stores the failure information in the scan tools Freeze Frame and/or the Failure Records.

Conditions for Clearing the MIL/DTC
- The VCM turns OFF the MIL after 3 consecutive drive trips when the test has Run and Passed.
- A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 22 °C (40 °F) from the startup coolant temperature and the engine coolant temperature is more than 70 °C (158 °F) during the same ignition cycle).
- Use the scan tool Clear Information function.

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.
- Improper knock Sensor torque specification. Refer to Fastener Note in Service Precautions. Torque the knock Sensor to 19 N.m (14 lbs ft).

Review the Fail 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.

An intermittent may be caused by any of the following conditions:
- A poor connection
- Rubbed through wire insulation
- A broken wire inside the insulation

Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Intermittents and Poor Connections Diagnosis.

If a repair is necessary, then refer to Wiring Repairs or Connector Repairs.

Steps 1 - 2:

Steps 3 - 6:

Steps 6 - 10:

Steps 11 - 14:

Steps 15 - 16:

Steps 17 - 18:

Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. Ensures that the condition is present.
6. Ensures that the knock sensor is capable of detecting detonation. Striking the lift bracket with a non-metallic object should produce a signal that the knock sensor should detect.