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 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 learns a minimum 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. If the ECM malfunctions in a manner that will not allow proper diagnosis of the KS system, DTC P0325 sets.
DTC Descriptors
This diagnostic procedure supports the following DTC:
DTC P0325 Knock Sensor (KS) Module Performance
Conditions for Running the DTC
| • | DTCs P0106, P0107, and P0108 are not set. |
| • | The engine speed is more than 1600 RPM. |
| • | The engine coolant temperature (ECT) is more than 50°C (122°F). |
| • | The engine vacuum is between 10-50 kPa, which is based on engine speed. |
| • | DTC P0325 runs continuously once the above conditions are met. |
Conditions for Setting the DTC
| • | The ECM detects an internal malfunction in the KS circuitry that will not allow for the correct diagnosis of the KS system. |
| • | The above condition is present for 4 seconds. |
Action Taken When the DTC Sets
| • | The control module stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records. |
| • | The driver information center, if equipped, may display a message. |
Conditions for Clearing the DTC
| • | 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 non-emission related diagnostic. |
| • | Clear the DTC with a scan tool. |
Step | Action | Yes | No |
|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Engine Controls? | Go to Step 2 | |
2 |
Did the DTC fail this ignition? | Go to Step 3 | Go to Intermittent Conditions |
3 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | Go to Step 4 | -- |
4 |
Did 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 |
