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 ECM monitors 2 separate KS, one on each side of the engine block. Each KS produces an AC voltage signal that varies with different engine speeds and loads. 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 uses the KS signal to calculate the average voltage, then assign a voltage range value. The ECM will then monitor for a normal KS signal within the assigned voltage range. If the ECM detects a KS signal outside of the assigned voltage range, or the KS signal is not present, this DTC will set. DTC P0327 refers to KS 2.
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
| • | The engine run time is more than 10 seconds. |
| • | The engine speed is greater than 1,000 RPM. |
| • | DTC P0327 and P0332 runs continuously when the above conditions are met. |
Conditions for Setting the DTC
The KS signal is outside of the assigned voltage range, or the signal is not present for 100 milliseconds.
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. |
Diagnostic Aids
| • | Inspect the KS for physical damage. A KS that is dropped or damaged may cause a DTC to set. |
| • | Inspect the KS for proper installation. A KS that is loose or over torqued may cause a DTC to set. The KS and the KS fastener should be free of thread sealant. The KS mounting surface must be free of burrs, casting flash, and foreign material. |
| • | The KS should be clear of hoses, brackets, and engine electrical wiring. |
| • | For an intermittent condition, refer to Testing for Intermittent Conditions and Poor Connections . |
Step | Action | Values | 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 |
Important: If an engine mechanical noise can be heard, repair the condition before proceeding with this diagnostic. Refer to Symptoms - Engine Mechanical .
Did the DTC fail this ignition? | -- | Go to Step 3 | Go to Diagnostic Aids |
3 |
Does the DMM display OL for both terminals? | -- | Go to Step 4 | Go to Step 8 |
4 |
Important: DO NOT tap on any plastic engine components. Does the DMM display a fluctuating frequency while tapping on the engine block? | -- | Go to Step 5 | Go to Step 8 |
5 |
Does the DMM display a voltage above the specified value on either circuit? | 4.3 V | Go to Step 6 | Go to Step 7 |
6 |
Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 11 |
7 |
Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 |
8 | Test for an intermittent and for a poor connection at the affected KS. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 10 |
9 | Test for an intermittent and for a poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 11 |
10 | Replace the affected KS. Refer to Knock Sensor Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- |
11 | Replace the ECM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 12 | -- |
12 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 13 |
13 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
