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 is located on the intake side of the engine block. 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 KS ground is supplied by the ECM through a low reference circuit. The ECM learns an average KS noise level using a calibrated average. The ECM should monitor a normal KS signal within the noise channel. When the ECM detects a KS signal that varies outside of the noise channel, the ECM will retard the spark timing until the knock goes away. If the ECM is operating on large amounts of spark retard and is unable to eliminate the knock, DTC P0326 will set.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0326 Knock Sensor (KS) Performance
Conditions for Running the DTC
| • | DTCs P0117, P0118, P0122, P0123, and P0327 are not set. |
| • | The engine speed is between 1,800-6,400 RPM. |
| • | The engine coolant temperature (ECT) is more than 70°C (158°F) |
| • | The manifold absolute pressure (MAP) is more than 55 kPa. |
| • | The engine run time is more than 20 seconds. |
| • | DTC P0326 runs continuously when the above conditions are met. |
Conditions for Setting the DTC
| • | KS average voltage is less than 0.01 volts or more than 4.99 volts for 10 seconds. |
| • | The KS signal indicates an engine knock is present. |
| • | The ECM commanded spark retard at a given engine load and speed 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 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. |
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Engine Control Module Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
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? | System OK | |
