Circuit Description
The knock sensor (KS) system 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 A/C signal that varies with different engine speeds and loads. The ECM makes adjustments to the spark timing based on the amplitude and frequency of either KS signal. The ECM receives the KS signal through a signal circuit. The ECM supplies the KS ground through a low reference circuit. The ECM uses the KS to calculate the amount of normal engine noise for a wide range of engine speeds and loads. The normal engine noise that has been calculated and retained in the ECM memory is called the learned noise channel. The ECM compares the actual KS signal to the learned noise channel in memory. When the ECM determines that the KS signal is outside the limits of the learned noise channel, the ECM will retard the spark timing until the knock goes away. If the knock is such that the engine requires a large amount of spark retard and the ECM is unable to eliminate the knock, this DTC will set. DTC P0326 refers to either the bank 1 KS or the bank 2 KS.
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 engine load is equal to or greater than a calibrated specification. |
| • | DTC P0326 runs continuously when the above conditions are met. |
Conditions for Setting the DTC
| • | The KS signal indicates an engine knock is present. |
| • | The ECM commanded spark retard at a given engine speed and load is more than the calibrated value. |
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 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 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. |
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 |
Did the DTC fail this ignition? | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections |
3 | Is DTC P0325 set? | Go to Step 4 | |
4 |
Did you find and correct the condition? | Go to Step 6 | Go to Step 5 |
5 |
Did you find and correct the condition? | Go to Step 6 | Go to Detonation/Spark Knock |
6 |
Did the DTC fail this ignition? | Go to Step 2 | Go to Step 7 |
7 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | System OK | |
