Circuit Description
The control module uses the knock sensors (KS) in order to detect engine detonation. Ignition control (IC) spark timing is retarded based on the KS signal input when spark knock is detected.
The control module monitors normal engine background noise during warm engine operation. It stores these noise values for comparison to the current knock sensor signal in order to help discriminate between normal engine noise and knock. If the amount of noise is below the minimum stored noise value, this diagnostic trouble code (DTC) will set.
Conditions for Running the DTC
| • | No active ECT sensor DTCs |
| • | No active TP sensor DTCs |
| • | Timing retard is 0 degrees or less |
| • | The system voltage is between 10-17 volts |
| • | The ECT is 60°C (140°F) or greater |
| • | The engine run time is 120 seconds or greater |
| • | The knock sensor noise is less than 3 counts |
| • | The engine speed is between 2,000-3,000 RPM |
| • | The throttle position is greater than 6 % |
Conditions for Setting the DTC
The difference between the actual noise value and the learned minimum noise value is less than 50 counts or more than 200 counts.
Action Taken When DTC Sets
| • | The VCM will not illuminate the MIL |
| • | The VCM will store the conditions which were present when the DTC set as a Fail Records data only. This information will not store as Freeze Frame Data. |
| • | The VCM will use a calculated spark retard value in order to minimize the knock during the conditions when the knock is most likely to occur. The calculated value will vary based on the engine speed and load. |
Conditions for Clearing the MIL or DTC
| • | The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed. |
| • | A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle. |
| • | Use a scan tool in order to clear the DTCs. |
Diagnostic Aids
Check for the following conditions:
| • | A poor connection at the VCM -- Inspect the knock sensor and the VCM connectors for the following items: |
| - | Backed out terminals |
| - | Broken locks |
| - | Improperly formed or damaged terminals |
| • | A misrouted harness -- Inspect the knock sensor harness in order to ensure that it is not routed too close to high voltage wires such as spark plug leads. |
Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
| • | Improper knock sensor torque specification. Torque the knock sensor to 19 N·m (14 lbs ft). |
Review the Failure Records vehicle mileage since the diagnostic test last failed in order to help determine how often the conditions that caused the DTC to set occur. This may assist in diagnosing the condition.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
Ensures that the fault is present.
-
Ensures that the knock sensor is capable of detecting detonation.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 |
Important: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and the Failure Records for reference. This data will be lost when the Clear DTC Information function is used. Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
Does the scan tool indicate the DTC P0327 failed this ignition? | -- | |||
3 |
Does the scan tool indicate the DTC P0327 Failed This Ign? | -- | Go to Diagnostic Aids | |
4 |
Is the voltage approximately at the specified value? | 5V | ||
5 | Measure the resistance of the Knock Sensor by connecting the DMM between the Knock Sensor terminal and the engine block. Is the resistance of the Knock Sensor near the specified value? | 100K ohms | ||
Is any signal indicated on the DVM while tapping on the engine lift bracket? | -- | |||
7 |
Was a problem found? | -- | ||
8 |
Was a problem found? | -- | ||
9 | Replace the Knock Sensor. Refer to Knock Sensor Replacement in Repair Instructions. Is action complete? | -- | -- | |
10 |
Was a problem found? | -- | ||
11 |
Was a problem found? | -- | ||
12 |
Does the scan tool indicate DTC P0327 Failed This Ign? | -- | ||
13 |
Is the action complete? | -- | -- | |
14 |
Does the scan tool indicate that this diagnostic ran and passed? | -- | ||
15 | Use the scan tool in order to display the Capture Info and the Review Capture Info functions. Are there any DTCs displayed that have not been diagnosed? | -- | Go to The Applicable DTC Table | System OK |
