Circuit Description
The knock sensor (KS) produces an AC voltage at all engine speeds and loads. The powertrain control module (PCM) then adjusts the spark timing based on the amplitude and the frequency of the KS signal. The PCM uses the KS signal to calculate the average voltage range. The PCM checks the KS and related wiring by comparing the actual knock signal to the calculated voltage range. A normal KS signal should stay within the calculated voltage range. If the PCM detects that the KS signal is outside the calculated voltage range or not present DTC P0327 sets.
Conditions for Running the DTC
| • | DTCs P0116, P0117, P0118, P0121, P0122, P0123, P0125, P1114, P1115, P1121, P1122 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) must be more than 60°C (140°F). |
| - | The engine RPM is between 475-975 for 10 seconds. |
| • | The engine coolant temperature (ECT) is more than 60°C (140°F). |
| • | The engine run time is more than 10 seconds. |
| • | The manifold absolute pressure (MAP) is less than 45 kPa. |
| • | The engine speed is between 1,700-3,000 RPM. |
| • | The system voltage is more than 10 volts. |
Conditions for Setting the DTC
The PCM detects that the KS signal is outside the calculated range or 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 knock sensor must be correctly tightened to 25 N·m (19 lb ft). |
| • | The mounting between the sensor and engine must be free of burrs, casting flash, and foreign material. |
| • | Ensure that the KS head is clear from hoses, brackets, and engine wiring. |
| • | If an intermittent is suspected, 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 Controls Connector End Views or Powertrain Control Module Connector End Views | ||||
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. Refer to Symptoms - Engine Mechanical in Engine Mechanical.
Does the DTC fail this ignition? | -- | Go to Step 3 | Go to Intermittent Conditions |
Does the voltage measure from below the specified value at idle to above the specified value at wide open throttle. | Below 50 mV to above 150 mV | Go to Step 4 | Go to Step 10 | |
4 | Test the knock sensor signal circuit and the knock sensor low reference circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 5 |
5 | 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 12 | Go to Step 6 |
6 | Test the KS signal circuit for a short to ground and for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 7 |
7 | Test the KS low reference circuit for a short to ground and for a short to voltage. 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 |
8 | Test for an intermittent and for a poor connection at the 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 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 KS. 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 | |
