Circuit Description
The Powertrain Control Module (PCM) contains integrated knock sensor (KS) diagnostic circuitry. An input signal from the KS is used to detect engine detonation, allowing the PCM to retard ignition control (IC) spark timing based on the amplitude and frequency of the KS signal being received. The KS produces an AC signal under all engine operating conditions. During engine operation, the PCM calculates the average voltage of the KS signal. If the knock sensor system is operating normally, the PCM will see KS signal voltage vary above and below the calculated voltage average. If the PCM detects KS input signal equal to the KS average voltage over 95 percent of a calibrated time, DTC P0327 will set.
Conditions for Running the DTC
| • | No TP, CMP, CKP, ECT sensor, or VSS DTCs are set. |
| • | Engine speed is between 1000 and 5000 RPM. |
| • | The engine has been running for a minimum of 30 seconds. |
| • | Throttle angle is more than 15 percent. |
| • | Engine load is more than 45 percent. |
| • | Engine coolant temperature (ECT) is more than 60°C (140°F). |
| • | Maximum spark retard is less than 15 degrees. |
| • | System voltage is more than 9.0 volts. |
Conditions for Setting the DTC
The PCM detects a KS signal voltage within the calculated average voltage range for at least 10 seconds.
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed. |
| • | The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed. |
| • | The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using the scan tool. |
Diagnostic Aids
Inspect for the following conditions:
| • | Poor connection at the PCM--Inspect KS and PCM connectors for: |
| - | Backed out terminals |
| - | Broken locks |
| - | Improperly formed or damaged terminals |
| • | Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
| • | Misrouted harness--Inspect the KS harness to ensure that it is not routed too close to high voltage wires such as spark plug leads. |
Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
Ensures that the malfunction is present.
-
If both the 24X crank sensor and the cam signal are not present the KS signal will stop updating and may set DTC P0327. The ignition positive voltage supply and the ground circuits need to be diagnosed using the DTC P0336.
-
If sent here from symptoms, proceed with the diagnostic table.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
|
Important: : If a mechanical engine knock can be heard, repair the engine mechanical
problem before proceeding with this diagnostic. Refer to
Engine Noise Diagnosis
in Engine Mechanical.
Does the scan tool indicate DTC P0327 failed this ignition? | -- | Go to Diagnostic Aids | ||
Using a scan tool, monitor the 24X crank sensor and the cam signal. Is the 24X signal and cam signal present? | -- | |||
Does the scan tool indicate DTC P0327 failed this ignition? | -- | Go to Diagnostic Aids | ||
5 |
Did you find a problem? | -- | ||
6 |
Did you find a problem? | -- | ||
7 | Replace the knock sensor. Refer to Knock Sensor Replacement . Is the action complete? | -- | -- | |
8 |
Does the scan tool indicate DTC P0327 failed this ignition? | -- | System OK |
