Circuit Description
The knock sensors produce an AC signal when specific frequencies are detected. When the engine operates, the powertrain control module (PCM) learns a minimum and maximum frequency of noise of normal engine operation. The knock sensor (KS) system monitors both knock sensors in order to determine if a knock is present. If the KS system determines that excessive knock is present, the PCM retards the spark timing based on the signals from the KS system. The PCM then retards the timing until no knock is present. When the PCM detects a frequency that is less than or more than a defined range, DTC P0327 will set for a failure in KS 1, which is located on bank 1 on the drivers side of the engine, or DTC P0332 will set for a failure in KS 2, which is located on bank 2 on the passenger side of the engine.
DTC Descriptors
This diagnostic procedure supports the following DTCs:
| • | DTC P0327 Knock Sensor (KS) 1 Circuit Low Frequency |
| • | DTC P0332 Knock Sensor (KS) 2 Circuit Low Frequency |
Conditions for Running the DTC
| • | DTCs P0117, P0118, P1114, P1115, P1120, P1220, or P1221 are not set. |
| • | The engine speed is between 1,600-3,000 RPM. |
| • | The manifold absolute pressure (MAP) is less than 45 kPa. |
| • | The engine coolant temperature (ECT) is more than 60°C (140°F). |
| • | The engine run time is more than 20 seconds. |
| • | The ignition voltage is more than 10 volts. |
| • | This diagnostic runs continuously when the above conditions are met. |
Conditions for Setting the DTC
The PCM determines that this frequency is less than or more than the expected amount for 3 seconds or more.
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
| • | Ensure that the KS is properly installed. A KS that is loose or over torqued may cause either DTC to set. |
| • | For an intermittent, refer to Testing for Intermittent Conditions and Poor Connections . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step verifies the malfunction is present.
-
This test will isolate the KS from the rest of the circuit.
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Tapping on the engine block near the appropriate KS will simulate an engine knock.
Step | Action | Value(s) | 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 | |||||||
|
Important: If an engine knock can be heard, repair the engine mechanical condition before proceeding with this diagnostic.
Does the scan tool indicate that this diagnostic failed this ignition? | -- | Go to Step 3 | Go to Diagnostic Aids | |||||||
Is the resistance of the KS within the specified range? | 93-107K ohms | Go to Step 4 | Go to Step 6 | |||||||
Important: DO NOT tap on plastic engine components. Is any signal indicated on the DMM while tapping on the engine block near the KS? | -- | Go to Step 5 | Go to Step 6 | |||||||
5 |
Refer to Circuit Testing . Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 7 | ||||||
6 | Replace the KS. Refer to Knock Sensor 1 Replacement or Knock Sensor 2 Replacement . Did you complete the replacement? | -- | Go to Step 9 | -- | ||||||
7 |
Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 8 | ||||||
8 | Replace the PCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 9 | -- | ||||||
9 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 10 | ||||||
10 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||||
