Circuit Description
The knock sensor (KS) system enables the powertrain control module (PCM) to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The KS system uses two sensors. The sensors are located underneath the intake manifold. Each KS produces an AC signal that varies at all engine speeds and loads. The PCM makes adjustments to the spark timing based on the amplitude and frequency of the KS signal. The PCM receives the KS signal through a signal circuit. The KS ground is supplied by the PCM through a low reference circuit. The PCM uses each KS to calculate the amount of normal engine noise, a noise channel, for a wide range of engine speeds and loads. The PCM compares the actual KS signal to the learned noise channel. When the PCM detects a KS signal that varies outside of the noise channel, the PCM will retard the spark timing until the knock goes away. If the knock is such that the vehicle operates on large amounts of spark retard and the PCM is unable to eliminate the knock, this DTC sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0326 Knock Sensor (KS) Performance
Conditions for Running the DTC
| • | The engine speed is more than 500 RPM. |
| • | The knock detection is enabled. |
| • | The MAP Sensor parameter is more than 56 kPa. |
| • | DTC P0326 runs continuously once the above conditions are met. |
Conditions for Setting the DTC
| • | The KS signal indicates an engine knock is present. |
| • | The PCM commanded spark retard at a given engine load, and speed is more than the calibrated value. |
| • | The condition is present for at least 4 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
For an intermittent condition, refer to Intermittent Conditions .
Step | Action | 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 - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
2 |
Did you find and correct the condition? | Go to Step 4 | Go to Step 3 |
3 |
Did you find and correct the condition? | Go to Step 4 | Go to Detonation/Spark Knock |
4 |
Does the DTC fail this ignition? | Go to Step 2 | Go to Step 5 |
5 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | System OK |
