Circuit Description
The PCM contains integrated Knock Sensor (KS) diagnostic circuitry. The PCM uses the circuitry to diagnose the KS sensors and related wiring. The PCM calculates an average voltage of each knock sensor's signals and takes instantaneous signal voltage readings. The PCM uses the instantaneous signal voltage readings to determine the state of the knock sensor circuitry. If the knock sensor system is operating normally, the PCM should monitor instantaneous KS signal voltage readings varying outside a voltage range above and below the calculated average voltage. If the PCM detects a Knock Sensor 1 signal voltage within the calculated average voltage range, DTC P0327 will set.
Conditions for Running the DTC
| • | No TAC, VSS, CKP sensor, CMP sensor, MAF sensor, or ECT sensor DTCs are set. |
| • | Engine speed: |
| - | Manual Transaxle - engine speed is between 1000 and 3000 RPM. |
| - | Automatic Transaxle - engine speed is between 1000 and 4000 RPM. |
| • | Throttle angle: |
| - | Manual Transaxle - Throttle angle is greater than 15%. |
| - | Automatic Transaxle - Throttle angle is greater than 3%. |
| • | Engine load: |
| - | Manual Transaxle - engine load is greater than 45%. |
| - | Automatic Transaxle - engine load is greater than 20%. |
| • | Engine coolant temperature is greater than 75°C (167°F). |
| • | Maximum spark retard is less than 15 degrees. |
| • | System voltage is greater than 9 volts. |
Conditions for Setting the DTC
| • | The PCM detects a Knock Sensor 1 signal voltage within the calculated average voltage range. |
| • | The condition is present for 300 3X reference periods (100 crankshaft revolutions). |
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed. |
| • | The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed. |
| • | The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using the scan tool. |
Diagnostic Aids
Check for the following conditions:
| • | Poor connection at the PCM or Knock Sensor 1. |
| Inspect knock sensor 1 and PCM connectors for backed out terminals, broken locks, and improperly formed or damaged terminals. |
| • | Misrouted harness. |
| Inspect the knock sensor harness to ensure that it is not routed too close to high voltage wires such as spark plug leads. |
Reviewing the Freeze Frame/Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This verifies the malfunction is present. The scan tool will indicate DTC Ran=Yes and Pass=Int if the failure is intermittent. This indicates the diagnostic passed this ignition cycle and failed this ignition cycle. At this point the resistance of the knock sensors should be verified to be in the correct range. If the knock sensor resistances are correct, test the KS system wiring connections. When inspecting the KS system connections, start at the KS system jumper harness connector located behind the intake manifold. Then inspect the connections at the PCM. Refer to the wiring schematic for the correct connector and terminal. Then inspect the connections at the appropriate knock sensor. Failure Records data does not include the parameter KS Activity, however other parameters may aid in locating the conditions under which an intermittent occurred.
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This test will isolate the Knock Sensor from the rest of the circuit.
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Tap on the engine block in the location of the appropriate knock sensor.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
|
Important: If an engine knock can be heard, repair the engine mechanical problem before proceeding with this diagnostic.
Does the scan tool indicate that this DTC failed this ignition? | -- | Go to Diagnostic Aids | ||
Does the resistance measure within the specified range? | 93-107Kohms | |||
Does the scan tool indicate a signal while tapping on the engine near the knock sensor? | -- | |||
5 | Test the KS signal circuit for an open, a short to voltage or a short to ground. Refer to Wiring Repairs . Did you find and correct the condition? | -- | ||
6 | Replace the Knock Sensor. Refer to Knock Sensor Replacement . Did you complete the replacement? | -- | -- | |
7 | Test the KS signal circuit for a poor connection at the PCM. Refer to Intermittents and Poor Connections Diagnosis and Connector Repairs . Did you find and correct the condition? | -- | ||
8 |
Important:: Program the replacement PCM. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Did you complete the replacement? | -- | -- | |
9 |
Does the DTC reset? | -- | ||
10 | Does the scan tool indicate any DTCs that you have not diagnosed? | -- | Go to the applicable DTC table | System OK |
