Diagnostic Instructions
DTC Descriptor
DTC P0327: Knock Sensor (KS) Circuit
Circuit/System Description
The knock sensor (KS) enables the engine control module (ECM) to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The KS produces an AC voltage signal that varies
depending on the vibration level during engine operation. The ECM adjusts the spark timing based on the amplitude and the frequency of the KS signal. The ECM receives the KS signal through a signal circuit. The ECM supples a ground circuit to the KS through
a low reference circuit. The ECM also supplies a shielded ground circuit to the KS. The ECM learns a KS noise level at idle and uses calibrated values for the rest of the engine speed range. The ECM should monitor a normal KS signal within the noise channel.
The circuits between the KS sensor and the ECM consist of the following circuits:
Conditions for Running the DTC
| • | The engine coolant temperature (ECT) is greater than 60°C (140°F). |
| • | The engine speed is greater than 1,600 RPM. |
| • | The manifold absolute pressure (MAP) is between 10-50 kPa which depends on engine speed. |
| • | DTC P0327 runs continuously once the above conditions are met. |
Conditions for Setting the DTC
The ECM detects an incorrect KS signal for greater than 4 seconds.
Action Taken When the DTC Sets
DTC P0327 is a Type C DTC.
Conditions for Clearing the DTC
DTC P0327 is a Type C DTC.
Diagnostic Aids
The following conditions could also set this DTC:
| • | 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. |
| • | The KS must be clear of hoses, brackets, and engine electrical wiring. |
| • | An electromagnetic interference (EMI) condition on the shielded ground circuit |
Reference Information
Schematic Reference
Engine Controls Schematics
Description and Operation
Knock Sensor (KS) System Description
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References
for scan tool information
Circuit/System Verification
- Engine running, observe the DTC information with a scan tool. DTC P0327 should not set.
- 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 data.
Circuit/System Testing
Important: If the knock sensor lead is damaged in any way, replace the knock sensor.
- Ignition OFF, disconnect the harness connector at the knock sensor.
- Ignition ON, connect a test lamp between the signal circuit terminal 1 and ground. The test lamp should not illuminate.
| ⇒ | If the test lamp illuminates, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM. |
- Connect a test lamp between the signal circuit terminal 1 and 12 volts. The test lamp should not illuminate.
| ⇒ | If the test lamp illuminates, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM. |
- Ignition OFF, test for 90-110K ohms of resistance between the signal circuit terminal 1 and the low reference circuit terminal 2.
| ⇒ | If not within the specified range, test the circuits for an open/high resistance. If the circuits test normal, replace the ECM. |
- If all circuits test normal, test or replace the KS sensor.
Repair Instructions
Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
