Circuit Description
The knock sensor system is used to detect engine detonation. The knock sensor produces an AC voltage signal. This signal is then sent to the KS module. The amplitude and frequency of the AC voltage signal is dependent upon the knock level being detected. The PCM will then retard the spark timing based on signals from the KS module.
Conditions for Setting the DTC
| • | The KS voltage is less than 0.19 volt or greater than 4.99 volts. |
| • | The engine speed is between 2200-6375 RPM. |
| • | The TP angle is greater than 5 percent. |
| • | One or both of the following DTCs are not set |
| P0122, P0123 |
| OR |
| • | The knock is present for greater than 4.5 seconds over a 5 second interval. |
| • | One or both of the following DTCs are not set |
| P0122, P0123 |
Action Taken when the DTC Sets
| • | The malfunction indicator lamp (MIL) will illuminate. |
| • | The PCM will default to 6° timing. |
Conditions for Clearing the DTC
| • | A history DTC P0325 will clear after 40 consecutive ignition cycles have occurred without a fault. |
| • | History and current DTC P0325 can be cleared by using a scan tool. |
| • | The MIL will turn OFF after passing three consecutive diagnostic test. |
Diagnostic Aids
Check and correct any abnormal engine noise before using the diagnostic chart.
Test Description
The numbers below refer to the step numbers on the diagnostic chart.
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If the conditions for the test as described above are met, a DTC P0325 will set and MIL will illuminate.
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The scan tool displays knock sensor activity in counts, approximately 35-50 at idle. The counts should increase when engine speed is increased and the counts should decrease when engine speed is decreased.
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Checking the internal resistance of the knock sensor verifies if the knock sensor is operating properly. Install breakout box whenever checking resistance. Refer to PCM Terminal End View in the beginning of this section for breakout box pin locations.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Was the On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | |
Does DTC P0325 set? | -- | Go to Step 3 | Go to Diagnostic Aids | |
3 | Listen to the engine while raising and lowering the engine speed. Is knock present? | -- | Go to Step 8 | Go to Step 4 |
Does the KS activity increase with the engine speed? | 2500 RPM | Go to Step 7 | Go to Step 5 | |
Important: The PCM must remain disconnected while taking the resistance reading. Failure to do this will result in an incorrect resistance reading. Is the measured resistance within the specified value? | 90-110K ohms | Go to Step 7 | Go to Step 6 | |
6 |
Was a repair necessary? | -- | Go to Step 7 | |
7 | Inspect the KS sensor electrical connection. If the KS sensor connection is OK, then replace the knock sensor. Is the knock condition gone? | -- | Go to Step 9 | |
8 | Repair the base engine problem. Is action complete? | -- | -- | |
9 | Replace the KS module. Is the knock condition fixed? | -- | Go to Step 10 | |
10 | Replace the PCM. Is action complete? | -- | -- | |
