Circuit Description
The knock sensors (KS) produce an AC signal under all engine operating conditions. When the engine is running, the powertrain control module (PCM) learns a minimum and maximum frequency of normal engine noise. The KS system monitors both knock sensors in order to determine if 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. The PCM continues to retard timing until no knock is present. If the PCM detects that the frequency is out of the normal range, DTC P0327 or P0332 will set.
Conditions for Running the DTC
| • | DTCs P0116, P0117, P0118, P0122, P0123, P0125, or P0128 are not set. |
| • | The minimum noise level must be learned. The minimum noise level is learned when the following conditions are met: |
| - | The engine coolant temperature (ECT) is more than 60°C (140°F). |
| - | The engine RPM is between 475-975 for 10 seconds. |
| • | The engine speed is between 1,500-3,000 RPM. |
| • | The manifold absolute pressure (MAP) is less than 45 kPa. |
| • | The engine run time is more than 10 seconds. |
| • | The ignition voltage is more than 10 volts. |
Conditions for Setting the DTC
The PCM detects that the affected KS signal is less than the expected amount for more than 9 seconds.
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
| Important: If the KS is dropped, the sensor must be replaced. |
| • | Inspect the KS for proper installation. A knock sensor that is loose or over torqued may cause the DTC to set. |
| • | If DTCs P0327 and P0332 are set at the same time, inspect for poor connections at the KS harness jumper, located at the left rear side of the intake manifold. |
| • | For an intermittent, refer to Intermittent Conditions . |
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||
2 |
Important: If an engine knock can be heard, repair the engine mechanical condition before proceeding with this diagnostic.
Did the DTC fail this ignition? | -- | Go to Step 3 | Go to Diagnostic Aids | ||||||
3 |
Is the resistance of the KS within the specified range? | 93K-107K ohms | Go to Step 4 | Go to Step 6 | ||||||
4 |
Important: Do not tap on any plastic engine components.
Does the voltage change on the DMM while tapping on the engine block near the KS? | -- | Go to Step 5 | Go to Step 10 | ||||||
5 | Test the affected KS signal circuit between the PCM and the KS inline harness connector for the following conditions:
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 8 | ||||||
6 |
Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 7 | ||||||
7 | 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 in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 10 | ||||||
8 | Test for an intermittent and for a poor connection at the KS inline harness connector. 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 12 | Go to Step 9 | ||||||
9 | Test for an intermittent and for a poor connection at the PCM. 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 12 | Go to Step 11 | ||||||
10 | Replace the affected knock sensor. Refer to Knock Sensor Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- | ||||||
11 | Replace the PCM. Refer to Powertrain Control Module Replacement . 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 | |||||||
