System Description
The knock sensor (KS) system is used to detect engine detonation, allowing the engine control module (ECM) to retard the ignition control spark timing based on the KS signal being received. The KS produces an AC signal so that, under a no-knock condition, the signal on the KS circuit measures about 0.007 volts AC. The KS signal's amplitude and frequency depend upon the amount of knock being experienced. The ECM monitors the KS signal and can diagnose the KS and circuitry.
Conditions for Setting the DTC
| • | The minimum difference between cylinders is greater than 0.4 percent. |
| • | Vacuum is less than the predetermined value, 10-50 kPa (1.5-7.3 psi), based on RPM. |
| • | The RPM is greater than 1,600. |
| • | Engine coolant temperature (ECT) is greater than 50°C (151°F). |
Action Taken When the DTC Sets
| • | The malfunction indicator lamp (MIL) will illuminate. |
| • | The ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Failure Records buffers. |
| • | A history DTC is stored. |
Conditions for Clearing the MIL/DTC
| • | A history DTC will clear after 40 consecutive warm-up cycles without a fault. |
| • | DTCs can be cleared by using the scan tool. |
| • | Disconnect the ECM battery feed for more than 10 seconds. |
Diagnostic Aids
Inspect and correct any abnormal engine noise before using the diagnostic table.
Any circuitry that is suspected as causing the complaint should be thoroughly inspected for the following conditions:
| • | Backed-out terminals |
| • | Improper mating |
| • | Broken locks |
| • | Improperly formed |
| • | Damaged terminals |
| • | Poor terminal-to-wire connection |
| • | Physical damage to the wiring harness |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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The On-Board Diagnostic System Check prompts the technician to complete some basic checks and store the Freeze Frame and Failure Records data on the scan tool, if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored on the scan tool for later reference.
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If the conditions for the test as described above are met, a DTC P0327 will set and the MIL will illuminate.
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If the engine has an internal knock or audible noise that causes a knocking type noise on the engine block, the KS may be responding to the noise.
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Measuring the internal resistance of the KS or inspecting the wiring to the KS is OK.
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Any circuitry that is suspected as causing the complaint should be thoroughly inspected for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wiring connections, or physical damage to the wiring harness.
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The replacement ECM must be reprogrammed. Refer to the latest Techline procedure for ECM reprogramming.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Perform an On-Board Diagnostic System Check. Was the check performed? | -- | Go to Step 2 | ||
Is the DTC set again? | -- | Go to Step 3 | Go to Step 6 | |
Listen to the engine while raising and lowering the engine speed. Is a knock or audible noise present? | -- | Go to Step 4 | Go to Step 5 | |
4 | Repair the mechanical engine problem, or loose bracket, or components as needed. Did you complete the repair? | -- | Go to Step 11 | -- |
Is the resistance between the specified range? | 90-110 k ohms | Go to Step 6 | Go to Step 8 | |
Inspect for a poor connection at the ECM connector KS signal circuit and repair as needed. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 7 | |
Did you complete the replacement? | -- | Go to Step 11 | -- | |
8 | Inspect the KS connector for a poor connection and repair as needed. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 9 |
9 | Inspect the KS signal circuit for an open, or a short to ground, or voltage and repair as needed. Did you find and correct the condition? | -- | Go to Step 11 | -- |
10 |
Did you complete the replacement? | -- | Go to Step 11 | -- |
11 |
Does the scan tool indicate that this diagnostic ran and passed? | -- | Go to Step 12 | Go to Step 2 |
12 | Are any DTCs displayed that have not been diagnosed? | -- | Go to applicable DTC table | System OK |
