Circuit Description
The knock sensor (KS) system is used in order to detect any engine detonation, or spark knock. The engine control module (ECM) will retard the spark timing based on the signals from the KS. The knock sensors produce an AC voltage that is sent to the ECM. The amount of AC voltage produced is proportional to the amount of knock.
An operating engine produces a normal amount of engine mechanical vibration, or noise. The KS will produce an AC voltage signal from this noise. When the engine is operating, the ECM will learn the minimum and maximum amplitude of the noise the engine produces. If the ECM detects that this amplitude is below the normal operating range, DTC P0327 or P0332 will set.
Conditions for Running the DTC
| • | The engine coolant temperature (ECT) sensor is more than 40°C (104°F). |
| • | The engine speed is more than 2000 RPM. |
| • | The volumetric efficiency is more than 40 percent. |
Conditions for Setting the DTC
The KS signal is below the normal operating range or the KS signal is not present.
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
| • | The KS must be torqued correctly. Refer to Knock Sensor 1 Replacement and Knock Sensor 2 Replacement . |
| • | The mounting between the sensor and engine must be free of burrs, casting flash, and foreign material. |
| • | The KS head must be clear from hoses, brackets, and engine wiring. |
| • | If the KS is dropped, the KS must be replaced. |
| • | If the sensor lead is damaged in any way, the sensor must be replaced. |
| • | For an intermittent condition, refer to Intermittent Conditions . |
Test Description
The number below refers to the step number on the diagnostic table.
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-Engine Controls? | -- | Go to Step 2 | |
2 |
Does the DTC fail this ignition cycle? | -- | Go to Step 3 | Go to Diagnostic Aids |
Does the DMM display OL or infinity? | -- | Go to Step 5 | Go to Step 4 | |
4 | Test the signal circuit and the low reference circuit of the KS for a short to ground . Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 6 |
5 | Test the KS signal circuit and the KS low reference circuit of the KS for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 9 |
6 | Test the KS signal circuit for a short to the KS low reference circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 7 |
7 | Test for an intermittent and for a poor connection at the KS pigtail. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 8 |
8 | Replace the KS. Refer to Knock Sensor 1 Replacement Knock Sensor 2 Replacement . Did you complete the replacement? | -- | Go to Step 11 | -- |
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 in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 10 |
10 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 11 | -- |
11 |
Does the DTC run and pass? | -- | Go to Step 12 | Go to Step 2 |
12 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
